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MoS2 Toxicity

Potential toxicity mechanism of MoS2 nanotube in the interaction between YAP65 WW domain and PRM

With the widespread application of Molybdenum disulfide (MoS2) in biomedicine, its mechanism of action with biomolecules has attracted increasing attention. Herein, molecular dynamics simulations were performed to investigate the effect of MoS2 nanotube on the binding of the signal protein YAP65, an important Yes kinase-associated protein domain (WW domain), to the proline rich motif ligand (PRM). We designed four systems based on the different initial binding modes among WW domain, PRM and MoS2 nanotube, and observed two ways to affect the binding of WW domain to PRM. The first pathway, the active site in WW domain was occupied by MoS2 nanotube, which prevents WW domain from binding to PRM. In the second pathway, WW domain was bound to PRM with residues W17 and F29 instead of the two highly conserved residues (Y28 and W39), forming an unstable combination. These two results might cause WW domain to lose its original function or to pass the mistaken signal. However, MoS2 nanotube did not destroy the structure and binding of WW domain and PRM in the composite. These findings shed light on the interaction between MoS2 nanotube and signal protein system, while providing another valuable insight into the potential nanotoxicity of MoS2 nanotube.

Y. J. Meng, R. R. Liu, M. Zhu, H. L. Zhai, and C. L. Ren,Potential toxicity mechanism of MoS2 nanotube in the interaction between YAP65 WW domain and PRM, Colloids and Surfaces B-Biointerfaces, 2020, 196.

XPS study of sulfide minerals surface oxidation under high-voltage nanosecond pulses

Surface modification of natural metal sulfides (pyrite, arsenopyrite, chalcopyrite, sphalerite, galena, and molybdenite) treated by high-power electromagnetic pulses (HPEMP treatment) has been studied by X-ray photoelectron spectroscopy as a function of HPEMP treatment duration. Two principal common steps and some differences in the surface evolution process were identified. The initial surface modification step was observed at low treatment doses (up to N ca 103 pulses). Formation or accumulation in the surface layer of metal-deficient sulfide phase, oxides and hydroxides, elemental/polysulfide sulfur and/or metastable sulfur (thiosulfate, sulfite) was observed at this step. The second step (N >= 3.103 pulses) is characterized by thermal loss of elemental sulfur. Differences in the modification process, it was found that the chemical transformations of sulfur in the surface layer of pyrite, arsenopyrite, chalcopyrite include accumulation/formation of S-0 (S-n(2-)) at the first transformation stage (up to N ca 103 pulses) followed by its removal. In the case of sphalerite and galena, the surface sulfur transformation had a different pattern. It included formation/accumulation at the first stage of metastable sulfur species (thiosulfate, sulfite) converted at an increase treatment duration to the initial state (sulfide or disulfide).

 

V. A. Chanturiya, I. Z. Bunin, and M. Ryazantseva,XPS study of sulfide minerals surface oxidation under high-voltage nanosecond pulses, Minerals Engineering, 2019, 143.

               

Adsorption of heavy metals on moybdenum disulfide in water: A critical review

Moybdenum disulfide (MoS2)-based nanomaterials stand out from two-dimensional (2D) materials as a promising adsorbent for the removal of heavy metals from aqueous solution due to their extremely marvelous adsorption performances. The superb uptake capacity is primarily ascribed to the intrinsically rich S atoms exposed on the surface of MoS2, which distinguishes MoS2-based nanomaterials from other 2D materials. This work presents the latest advances of MoS2 nanomaterials as adsorbent for the removal of heavy metal ions in water. Various preparation methods, as well as the structure, property and modification of MoS2, is summarized. The adsorption capacity and mechanisms, affecting factors and regeneration are highlighted. The practical application of MoS2 as potential adsorbent for the removal of heavy metals from water is emphasized, and research needed for future application is simultaneously identified. (C) 2019 Elsevier B.V. All rights reserved.

C. Liu, Q. M. Wang, F. F. Jia, and S. X. Song,Adsorption of heavy metals on moybdenum disulfide in water: A critical review, Journal of Molecular Liquids, 2019, 292.

A Near-Infrared-Controllable Artificial Metalloprotease Used for Degrading Amyloid-beta Monomers and Aggregates

Proteolysis of amyloid-beta (A beta) is a promising approach against Alzheimer's disease. However, it is not feasible to employ natural hydrolases directly because of their cumbersome preparation and purification, poor stability, and hazardous immunogenicity. Therefore, artificial enzymes have been developed as potential alternatives to natural hydrolases. Since specific cleavage sites of A beta are usually embedded inside the beta-sheet structures that restrict access by artificial enzymes, this strongly hinders their efficiency for practical applications. Herein, we construct a NIR (near-IR) controllable artificial metalloprotease (MoS2-Co) using a moybdenum disulfide nanosheet (MoS2) and a cobalt complex of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (Codota). Evidenced by detailed experimental and theoretical studies, the NIR-enhanced MoS2-Co can circumvent the restriction by simultaneously inhibition of beta-sheet formation and destroying beta-sheet structures of the preformed A beta aggregates in living cell. Furthermore, our designed MoS2-Co is an easy to graft A beta-target agent that prevents misdirected or undesirable hydrolysis reactions, and has been demonstrated to cross the blood brain barrier. This method can be adapted for hydrolysis of other kinds of amyloids.

M. M. Ma, Y. Wang, N. Gao, X. P. Liu, Y. H. Sun, J. S. Ren, and X. G. Qu,A Near-Infrared-Controllable Artificial Metalloprotease Used for Degrading Amyloid-beta Monomers and Aggregates, Chemistry-a European Journal, 2019, 25, 11852-11858.

 

Recent advances in two-dimensional transition metal dichalcogenides for biological sensing

Layered transition metal dichalcogenides (TMDs) are important members in the family of two-dimensional (2D) materials. The large surface-to-volume ratio, combined with the fascinating tunable electronic and optical properties, low toxicity, unique van der Waals layered structure, and engineerable surface structure, renders 2D TMDs highly valuable for next-generation biosensing applications. Herein, the recent progress in the development of 2D TMDs-based biosensors is comprehensively reviewed, with special focus on the implementation of the structural, electronic and optical properties of 2D TMDs in the realization of high-performance biosensors with different configurations for a wide spectrum of bioanalytes and bio-species. In addition, the comparison on biosensing performances with graphene as the currently most studied 2D candidate is critically discussed. Finally, future perspectives are provided along the development progress of 2D TMDs-based biosensors which are currently undergoing an intense study. This work will lead researchers to explore more novel sensing candidates within the category of TMDs with exotic chemical composition, structure, morphologies, dimensionalities, and properties.

H. W. Hu, A. Zavabeti, H. Y. Quan, W. Q. Zhu, H. Y. Wei, D. C. Chen, and J. Z. Ou,Recent advances in two-dimensional transition metal dichalcogenides for biological sensing, Biosensors & Bioelectronics, 2019, 142.

 

Acid sites on silica-supported moybdenum oxides probed by ammonia adsorbtion: Experiment and theory

The origin of Bronsted acidity in a series of silica-supported moybdenum oxide catalysts with Mo loadings of 2.1-13.3 wt%, and apparent Mo surface densities of 0.2-2.5 nm–2, respectively, was analyzed by ammonia adsorption investigated by temperature-programmed desorption, infrared spectroscopy, and DFT calculations. Every surface moybdenum atom in the moybdenum oxide (sub-)monolayer is involved in the interaction with ammonia, either as Lewis or as Bronsted acid site. A model is proposed that ascribes Bronsted acidity to the interaction between silanol groups and adjacent surface molybdate species under formation of pseudo-bridging Si-O(H)-Mo(=O)2 species with a Mo-O(Si) distance of 2.1 angstrom and a N-H(OSi) distance of < 1.1 angstrom in the formed adsorption complex of the ammonia molecule. The combined experimental and computational study contributes to an improved fundamental understanding of acidity in amorphous mixed metal oxides.

K. Arnakawa, Y. Q. Wang, J. Krohnert, R. Schlogl, and A. Trunschke,Acid sites on silica-supported moybdenum oxides probed by ammonia adsorbtion: Experiment and theory, Molecular Catalysis, 2019, 478.

 

 

Self-fluorescent antibiotic MoOx-hydroxyapatite: a nano-theranostic platform for bone infection therapies

Nowadays, the repair of large-size bone defects represents a huge medical challenge. A line of attack is the construction of advanced biomaterials having multifunctional properties. In this work, we show the creation of biocompatible MoOx-hydroxyapatite nanoparticles (nano-HA/MoOx) that simultaneously exhibit self-activated fluorescence and antibiotic skills. Along this text, we demonstrate that the insertion of moybdenum, an essential trace element, into the non-stoichiometric calcium deficient hydroxyapatite lattice generates intrinsic electronic point defects that exacerbate its epifluorescence blue emission and provokes new red emissions, preserving, always, its bioactivity. Furthermore, these point defects, acting as electron acceptors, stimulate the materials' biological redox status and promote the death of pathogen microorganisms after their direct contact. A putative mechanism, by which bacteria lose electrons from their metabolic circuit that alter the function of their cytoplasmic membrane and potentially die, agrees with our results. Our findings highlight the importance of tuning the electronic communications between biomaterial interfaces and biological units, and support the use of self-fluorescent MoOx-hydroxyapatite nanoparticles as fundamental building blocks for new real-time imaging platforms against bone infection.

D. Placente, J. M. Ruso, M. Baldini, J. A. Laiuppa, J. M. Sieben, G. E. Santillan, and P. V. Messina,Self-fluorescent antibiotic MoOx-hydroxyapatite: a nano-theranostic platform for bone infection therapies, Nanoscale, 2019, 11, 17277-17292.

               

MOLYBDENOCENE

New multinuclear Scaffold molybdocene-gold lidocaine complex: DNA/HSA binding, molecular docking, cytotoxicity and mechanistic insights

The new heteronuclear molybdocene-gold complex 1, [(eta(5)-Cp)(2)Mo-II[(mu(2)-eta(2)-dtc)(2)Nap]Au-III(LC)](PF6), (eta(5)-Cp: eta(5)-cyclopentadienyl, (dtc)(2)Nap: 2,7-bis(dithiocarbamate) naphthalene, LC: lidocaine) was synthesized and evaluated for biological activity. With the aim of assessing the possible DNA-binding mode, the interaction of the complex 1 with calf thymus DNA (CT DNA) was investigated by UV spectroscopy, emission titration, and viscosity measurement. Also, the binding of the complex to human serum albumin (HSA) was considered by UV-Vis and fluorescence emission spectroscopy. Moreover, molecular docking was used for modeling of the binding of the complex to DNA and HSA. These experimental results were confirmed by the results of molecular docking concerning the lowest binding energy. The cytotoxicity of the heterometallic complex 1 has been evaluated against a panel of several cancer cell lines with low micromolar IC50 (72 h) values, according to its cellular uptake and also versus HEK293 nonmalignant fibroblasts. Moreover, the complex 1 showed the induction of apoptotic process. [GRAPHICS] .

F. Abyar, and L. Tabrizi,New multinuclear Scaffold molybdocene-gold lidocaine complex: DNA/HSA binding, molecular docking, cytotoxicity and mechanistic insights, Journal of Biomolecular Structure & Dynamics, 2019, 37, 3366-3378.

 

Molybdenum powder water remediation

Singlet Oxygen Triggered by Superoxide Radicals in a Molybdenum   Cocatalytic Fenton Reaction with Enhanced REDOX Activity in the Environment

As an important reactive oxygen species (ROS) with selective oxidation, singlet oxygen (1O2) has wide application prospects in biology and the environment. However, the mechanism of 1O2 formation, especially the conversion of superoxide radicals (.O2) to 1O2, has been a great controversy. This process is often disturbed by hydroxyl radicals (.OH). Here, we develop a molybdenum   cocatalytic Fenton system, which can realize the transformation from .O2to 1O2 on the premise of minimizing .OH. The Mo(0) exposed on the surface of molybdenum   powder can significantly improve the Fe3+)/Fe2+ cycling efficiency and weaken the production of .OH, leading to the generation of .O2Meanwhile, the exposed Mo6+ can realize the transformation of .O2 to 1O2. The molybdenum   cocatalytic effect makes the conventional Fenton reaction have high oxidation activity for the remediation of organic pollutants and prompts the inactivation of Staphylococcus aureus, as well as the adsorption and reduction of heavy metal ions (Cu2+, Ni2+, and Cr6+). Compared with iron powder, molybdenum   powder is more likely to promote the conversion from Fe3+to Fe2+ during the Fenton reaction, resulting in a higher Fe2+/Fe3+ ratio and better activity regarding the remediation of organics. Our findings clarify the transformation mechanism from .O2to 1O2during the Fenton-like reaction and provide a promising REDOX Fenton-like system for water treatment.

Q. Yi, J. Ji, B. Shen, C. Dong, J. Liu, J. Zhang, and M. Xing,Singlet Oxygen Triggered by Superoxide Radicals in a Molybdenum   Cocatalytic Fenton Reaction with Enhanced REDOX Activity in the Environment, Environmental science & technology, 2019, 53, 9725-9733.

Alloy implant

Additively manufactured calcium phosphate reinforced CoCrMo alloy: Bio-tribological and biocompatibility evaluation for load-bearing implants

Cobalt-chromium-molybdenum   (CoCrMo) alloys are widely used in load-bearing implants; specifically, in hip, knee, and spinal applications due to their excellent wear resistance. However, due to in vivo corrosion and mechanically assisted corrosion, metal ion release occurs and accounts for poor biocompatibility. Therefore, a significant interest to find an alternative to CoCrMo alloy exists. In the present work we hypothesize that calcium phosphate (CaP) will behave as a solid lubricant in CoCrMo alloy under tribological testing, thereby minimizing wear and metal ion release concerns associated with CoCrMo alloy. CoCrMo-CaP composite coatings were processed using laser engineered net shaping (LENS) system. After LENS processing, CoCrMo alloy was subjected to laser surface melting (LSM) using the same LENS set-up. Samples were investigated for microstructural features, phase identification, and biocompatibility. It was found that LSM treated CoCrMo improved wear resistance by 5 times. CoCrMo-CaP composites displayed the formation of a phosphorus-based tribofilm. In vitro cell-material interactions study showed no cytotoxic effect. Sprague-Dawley rat and rabbit in vivo study displayed increased osteoid formation for CoCrMo-CaP composites, up to 2 wt.% CaP. Our results show that careful surface modification treatments can simultaneously improve wear resistance and in vivo biocompatibility of CoCrMo alloy, which can correlate to a reduction of metal ion release in vivo.

A. Bandyopadhyay, A. Shivaram, M. Isik, J. D. Avila, W. S. Dernell, and S. Bose,Additively manufactured calcium phosphate reinforced CoCrMo alloy: Bio-tribological and biocompatibility evaluation for load-bearing implants, Additive manufacturing, 2019, 28, 312-324.

               

MoO2 nano

Size Induced Structural Changes in Molybdenum  Oxide Nanoparticles

Nanosizing of metal oxide particles is a common strategy for improving materials properties; however, small particles often take structures different from the bulk material. MoO2 nanoparticles show a structure that is distinct from the bulk distorted rutile structure and which has not yet been determined. Here, we present a model for nanostructured MoO2 obtained through detailed atomic pair distribution function analysis combined with high-resolution electron microscopy. Defects occur in the arrangement of [MoO6] octahedra, in both large (40-100 nm) nanoparticles, where the overall distorted rutile structure is preserved, and in small nanoparticles (<5 nm), where a new nanostructure is formed. The study provides a piece in the puzzle of understanding the structure/properties relationship of molybdenum   oxides and further our understanding of the origin of structural changes taking place upon nanosizing in oxide materials.

T. L. Christiansen, E. D. Bojesen, M. Juelsholt, J. Etheridge, and K. M. O. Jensen,Size Induced Structural Changes in Molybdenum   Oxide Nanoparticles, ACS Nano, 2019, 13, 8725-8735.

               

MoO3 milled

Mechanical Milling Influence on Lattice Vibrational Behaviour of MoO3-V2O5 Composite Nanopowders

The present work aimed to synthesise an ultrafine thermally excellent MoO3-V2O5 nanocomposite powders using mechanical milling synthesis technique at different time intervals. Spectroscopic characterizations like Powder X-ray diffraction (PXRD), Scanning Electron Microscope, Electron Dispersive X-ray Spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, Raman, optical absorption and Thermogravimetric and Differential Thermal Analysis were used to characterize the synthesised composite powders. The orthorhombic phases of MoO3 and V2O5 are revealed by the X-Ray peak profile. The average crystalline sizes and lattice strain evaluated from XRD data and W-H plot calculations were found to be nearly equal. The qualitative information of the prepared nanocomposite is revealed from Raman analysis. The vibrational modes of Raman spectra also reveal the orthorhombic phases of the prepared Nanocomposite. The depositions of vanadium powders on molybdenum   are revealed by SEM images. The fundamental modes of Mo=O and V=O and other functional groups were analysed by FT-IR. Thermogravimetry analysis and Differential Thermal Analysis (DTA) of MoO3-V2O5 revealed that, the composite is stable up to 670 degrees C with an insignificant weight loss. Hence the synthesised mixed lubricious oxide nanocomposite may be used as a solid lubricant at elevated temperatures.

D. Sundeep, T. V. Kumar, M. K. Kumar, A. G. Krishna, and R. RaviKumar,Mechanical Milling Influence on Lattice Vibrational Behaviour of MoO3-V2O5 Composite Nanopowders, Silicon, 2019, 11, 1517-1524.

MoO3

PHOTOCATALYSIS

WATER PURIFICATION

Direct Z-Scheme charge transfer in heterostructured MoO3/g-C3N4 photocatalysts and the generation of active radicals in photocatalytic dye degradations

Photocatalytic degradation is an attractive strategy to purify waste water contaminated by macromolecular organics. Compared with the single-component photocatalysts, heterostructures of different semiconductors have been widely used to improve the photocatalytic performance. In this work, we fabricate a hetero-structured photocatalyst consisting of two-dimensional graphitic carbon nitride (g-C3N4) nanosheets and commercial MoO3 microparticles through a simple mixing and annealing process. The photocatalytic performance was evaluated in various dye degradation reactions, especially Rhodamine (RhB) degradation. The MoO3/g-C3N4 composite shown a significant improvement compared with individual MoO3 or g-C3N4 as well as their physical mixture. By applying electron spin resonance (ESR) spin-trap spectra, radical scavenge experiments and electrochemical analysis, we find that a direct Z-scheme charge transfer between MoO3 and g-C3N4 not only causes an accumulation of electrons in g-C3N4 and holes in MoO3, but also boosts the formation of superoxide radical and hydroxyl radical. The superoxide radical and hole dominate the photocatalytic degradation, while the hydroxyl radical plays a negligible role and its production can be suppressed by lowering the pH value.

S. Xue, C. Wu, S. Pu, Y. Hou, T. Tong, G. Yang, Z. Qin, Z. Wang, and J. Bao,Direct Z-Scheme charge transfer in heterostructured MoO3/g-C3N4 photocatalysts and the generation of active radicals in photocatalytic dye degradations, Environmental pollution (Barking, Essex : 1987), 2019, 250, 338-345.

Health, Safety & Environment

MoS2 BIO TRANSPORT

Molybdenum derived from nanomaterials incorporates into molybdenum enzymes and affects their activities in vivo

Many nanoscale biomaterials fail to reach the clinical trial stage due to a poor understanding of the fundamental principles of their in vivo behaviour. Here we describe the transport, transformation and bioavailability of MoS2 nanomaterials through a combination of in vivo experiments and molecular dynamics simulations. We show that after intravenous injection molybdenum is significantly enriched in liver sinusoid and splenic red pulp. This biodistribution is mediated by protein coronas that spontaneously form in the blood, principally with apolipoprotein E. The biotransformation of MoS2 leads to incorporation of molybdenum into molybdenum enzymes, which increases their specific activities in the liver, affecting its metabolism. Our findings reveal that nanomaterials undergo a protein corona-bridged transport-transformation-bioavailability chain in vivo, and suggest that nanomaterials consisting of essential trace elements may be converted into active biological molecules that organisms can exploit. Our results also indicate that the long-term biotransformation of nanomaterials may have an impact on liver metabolism.

M. Cao, R. Cai, L. Zhao, M. Guo, L. Wang, Y. Wang, L. Zhang, X. Wang, H. Yao, C. Xie, Y. Cong, Y. Guan, X. Tao, Y. Wang, S. Xu, Y. Liu, Y. Zhao, and C. Chen,Molybdenum derived from nanomaterials incorporates into molybdenum enzymes and affects their activities in vivo, Nat Nanotechnol, 2021. https://doi.org/10.1038/s41565-021-00856-w

             

MoS2

A critical review on the applications and potential risks of emerging MoS2 nanomaterials

Molybdenum disulfide (MoS2) nanomaterials have been widely used in various fields such as energy store and transformation, environment protection, and biomedicine due to their unique physicochemical properties. Unfortunately, such large-scale production and use of MoS2 nanomaterials would inevitably release into the environmental system and then potentially increase the risks of wildlife/ecosystem and human beings as well. In this review, we first introduce the physicochemichemical properties, synthetic methods and environmental behaviors of MoS2 nanomaterials and their typical functionalized materials, then summarize their environmental and biomedical applications, next assess their potential health risks, covering in vivo and in vitro studies, along with the underlying toxicological mechanisms, and last point out some special phenomena about the balance between applications and potential risks. This review aims to provide guidance for harm predication induced by MoS2 nanomaterials and to suggest prevention measures based on the recent research progress of MoS2' applications and exerting toxicological data.

Z. Xu, J. Lu, X. Zheng, B. Chen, Y. Luo, M. N. Tahir, B. Huang, X. Xia, and X. Pan,A critical review on the applications and potential risks of emerging MoS2 nanomaterials, J Hazard Mater, 2020, 399, 123057.

             

 

Transition metal dichalcogenides for biomedical applications [Review]

Two-dimensional (2D) materials[MoS2} have been an area of substantial interest since the isolation of graphene. Graphene has been extensively studied for its unique intrinsic properties, but its absence of electronic bandgap has been a constant driving force behind the search for a more promising alternative. Two-dimensional transition metal dichalcogenides (2D TMDs) have tremendous potential in replacing graphene due to their fascinating properties of direct bandgap, atom-scale thickness, strong spin-orbit coupling, and outstanding mechanical, chemical, physical, electronic, and optical characteristics. These have provided the drive for its fundamental studies and manifold applications in high-end electronics, optoelectronics, and medical devices. In this context, this chapter aspires to critically evaluate 2D TMDs for the recent endeavors in biomedical research. This primarily encompasses the synthetic methods, vital structural attributes, and chemical and physical attributes pertaining to their potential in biomedical applications. Herein, the recent efforts and advances in the exploration of 2D TMDs for biomedical applications have been comprehended, discussing the advantages, restrictions, and candidatures of each material.

R. R. Dutta, R. Devi, H. S. Dutta, and S. Gogoi Transition metal dichalcogenides for biomedical applications, 2020, Chapter 7 - Transition metal dichalcogenides for biomedical applications,

Editor(s): Raju Khan, Shaswat Barua, Two-Dimensional Nanostructures for Biomedical Technology,Elsevier,

2020,Pages 211-247,ISBN 9780128176504,https://doi.org/10.1016/B978-0-12-817650-4.00007-3.

(http://www.sciencedirect.com/science/article/pii/B9780128176504000073)

DNA AND PHOSPHATE

Electrochemical assay for analysis of circulation tumor cells based on isolation of the cell with magnetic nanoparticles and reaction of DNA with molybdate

A universal strategy was developed for the analysis of circulating tumour cells (CTCs) based on reaction of DNA in the cells with molybdate. Initially, CTCs were enriched and isolated from samples by magnetic nanoparticles. Then, after killing the isolated cells by heat treatment, the cell membrane was raptured, and the DNA molecules contained in the cells were released. The following reaction of the released DNA molecules with molybdate can form redox molybdophosphate, resulting in electrochemical current. This electrochemical assay can be applied to the detection of different CTCs as long as the CTCs can be isolated from the samples, with a universal signal detection method, without additional signal amplification strategies. Breast cancer cell MCF-7 was chosen as a model CTC for this study. At a working potential of 0.2 V vs. Ag/AgCl electrode, the electrochemical current is linearly related to the MCF-7 cell concentration from 5 to 1000 cells mL–1 with a limit of detection of 2 cells mL–1. The assay was successfully applied for detection of MCF-7 in human blood samples. This electrochemical assay can be applied for detection of different CTCs and also for simultaneous detection of CTCs. Graphical abstract A universal strategy was developed for the analysis of circulating tumor cells (CTCs) based on reaction of DNA contained in the cells with molybdate.

Y. Hou, J. Chen, B. Xie, T. Li, and M. Yang,Electrochemical assay for analysis of circulation tumor cells based on isolation of the cell with magnetic nanoparticles and reaction of DNA with molybdate, Mikrochimica acta, 2020, 187, 420.

MoS2

Comparative analysis of biological effects of molybdenum(IV) sulfide in the form of nano- and microparticles on human hepatoma HepG2 cells grown in 2D and 3D models

Significance of MoS2 nanoparticles as a lubricant or drug carriers indicates the need to assess their safety. In the study we analyzed the effects of MoS2 nano- and microparticles and their internalization in vitro, using 2D and 3D culture models of human hepatoma HepG2 cell line. MoS2 micro- and nanoparticles were characterized with high resolution electron microscopy (HR-SEM), X-ray diffraction (XRD) and Energy Dispersive X-Ray Spectroscopy (EDS). The cells were exposed to a range of concentrations of the nano-and microparticles suspensions (maximum of 250 μg/mL) for 72 h. Cell viability was assessed using WST-1 reduction test and LDH release assay. Particle internalization was analyzed using scanning transmission electron microscopy (STEM). The nanoparticles were internalized into the 2D and 3D cultured cells, in spheroids more efficiently into the outer layer. For microparticles mainly particles of less than 1 μm in diameter underwent internalization. This process, however, did not affect cell viability as measured with the WST-1 and LDH assays. STEM observation showed well preserved integrity of the cell membrane and no apparent cytotoxic effect. Although the particles seemed to be safely sequestered in vacuoles or the cytoplasm, their fate and eventual biological effects are not certain and deserve further studies.

Z. Sobańska, K. Domeradzka-Gajda, M. Szparaga, J. Grobelny, E. Tomaszewska, K. Ranoszek-Soliwoda, G. Celichowski, L. Zapór, K. Kowalczyk, and M. Stępnik,Comparative analysis of biological effects of molybdenum(IV) sulfide in the form of nano- and microparticles on human hepatoma HepG2 cells grown in 2D and 3D models, Toxicology in vitro : an international journal published in association with BIBRA, 2020, 68, 104931.

Immunological Responses Induced by Blood Protein Coronas on Two-Dimensional MoS2 Nanosheets

Two-dimensional (2D) nanosheets (NSs) have a large surface area, high surface free energy, and ultrathin structure, which enable them to more easily penetrate biological membranes and promote adsorption of drugs and proteins. NSs are capable of adsorbing a large amount of blood proteins to form NSs-protein corona complexes; however, their inflammatory effects are still unknown. Therefore, we investigated the pro-inflammatory effect of 2D model nanosheet structures, molybdenum disulfide (MoS2), and the MoS2 NSs-protein complexes with four abundant proteins in human blood, i.e., human serum albumin (HSA), transferrin (Tf), fibrinogen (Fg), and immunoglobulin G (IgG). The interactions between the NSs and the proteins were analyzed by quantifying protein adsorption, determining binding affinity, and correlating structural changes in the protein corona with the uptake of NSs by macrophages and the subsequent inflammatory response. Although all of the NSs-protein complexes induced inflammation, IgG-coated and Fg-coated NSs triggered much stronger inflammatory effects by producing and releasing more cytokines. Among the four proteins, IgG possessed the highest proportion of beta-sheets and led to fewer secondary structure changes on the MoS2 nanosheets. This can facilitate uptake and produce a stronger pro-inflammatory response in macrophages due to the recognition of an NSs-IgG complex by Fc gamma receptors and the subsequent activation of the NF-kappaB pathways. Our results demonstrate that the blood protein components contribute to the inflammatory effects of nanosheets and provide important insights for the nanosafety evaluation and the rational design of nanomedicines in the future.

D. Baimanov, J. Wu, R. Chu, R. Cai, B. Wang, M. Cao, Y. Tao, J. Liu, M. Guo, J. Wang, X. Yuan, C. Ji, Y. Zhao, W. Feng, L. Wang, and C. Chen,Immunological Responses Induced by Blood Protein Coronas on Two-Dimensional MoS2 Nanosheets, ACS nano, 2020, 14, 5529–5542.

THIOMOLYBDATE

Relative abundance of thiolated species of as, Mo, W, and Sb in hot springs of Yellowstone National Park and Iceland [thiomolybdates]

Geothermal waters often are enriched in trace metal(loid)s, such as arsenic, antimony, molybdenum, and tungsten. The presence of sulfide can lead to the formation of thiolated anions; however, their contributions to total element concentrations typically remain unknown because nonsuitable sample stabilization and chromatographic separation methods convert them to oxyanions. Here, the concurrent widespread occurrence of thioarsenates, thiomolybdates, thiotungstates, and thioantimonates, in sulfide-rich hot springs from Yellowstone National Park and Iceland is shown. More thiolation was generally observed at higher molar sulfide to metal(loid) excess (Iceland > Yellowstone). Thioarsenates were the most prominent and ubiquitous thiolated species, with trithioarsenate typically dominating arsenic speciation. In some Icelandic hot springs, arsenic was nearly quantitatively thiolated. Also, for molybdenum, thioanions dominated over oxyanions in many Icelandic hot springs. For tungsten and antimony, oxyanions typically dominated and thioanions were observed less frequently, but still contributed up to a few tens of percent in some springs. This order of relative abundance (thioarsenates > thiomolybdates > thiotungstates approximately thioantimonates) was also observed when looking at processes triggering transformation of thioanions such as mixing with non-geothermal waters or H Toxicity S degassing and oxidation with increasing distance from a discharge. Even though to different extents, thiolation contributed substantially to speciation of all four elements studied, indicating that their analysis is required when studying geothermal systems.

B. Planer-Friedrich, J. Forberg, R. Lohmayer, C. F. Kerl, F. Boeing, H. Kaasalainen, and A. Stefansson, Relative abundance of thiolated species of as, Mo, W, and Sb in hot springs of Yellowstone National Park and Iceland, Environ Sci Technol, 2020,54, 7, 4295-4304.

MoO2 PEROXIDASE MIMIC

Colorimetric assay of acetylcholinesterase inhibitor tacrine based on MoO2 nanoparticles as peroxidase mimetics

Molybdenum dichalcogenides MoX2 (X=S, Se) have been found to possess intrinsic peroxidase-like activity. However, molybdenum oxides (MoO2) as peroxidase mimetics have not been exploited yet. Herein, MoO2 nanoparticles were synthesized by a simple hydrothermal method and found to possess the peroxidase-like activity for the first time. MoO2 nanoparticles could catalyze the oxidation of 3,3',5,5'-tetrametylbenzidine (TMB) by H2O2 to produce a blue-color product (oxTMB). The catalytic property and mechanism were investigated by stead-state kinetics experiment and free radicals scavenging experiment, respectively. Acetylcholinesterase (AChE) could catalyze the hydrolysis of acetylthiocholine chloride (ATCh) into thiocholine (TCh), which could reduce oxTMB to decrease the absorbance in solution. In the presence of AChE inhibitor tacrine, the generation of TCh was inhibited and the absorbance was preserved. Based on these properties, a colorimetric assay method was developed for AChE inhibitor tacrine. This work not only broadens the application of the peroxidase mimetics, but also overcome the disadvantages of traditional methods such as expensive, complex and vulnerable to background interference for colorimetric assay of AChE inhibitor.

L. Huang, Z. Li, and L. Guo,Colorimetric assay of acetylcholinesterase inhibitor tacrine based on MoO2 nanoparticles as peroxidase mimetics, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2020, 224, 117412.

               

               

MoS2 IMMUNE RESPONSE

The molecular mechanism of robust macrophage immune responses induced by PEGylated molybdenum disulfide [PolyEthylene Glycol]

Molybdenum disulfide (MoS2), a representative hexagonal transition metal dichalcogenide (TMD), has been extensively exploited in biomedical applications due to its unique physicochemical properties and biocompatibility. However, the lack of adequate data regarding how MoS2 activates immunological responses of macrophages remains a key concern for its risk assessment. Here, we employ a combined theoretical and experimental approach to investigate the interactions of MoS2 and PEGylated MoS2 (MoS2-PEG) with macrophages. We first perform molecular dynamics simulations to examine the atomic-detailed interactions of MoS2 and MoS2-PEG nanoflakes with a realistic model of the macrophage membrane. We show that a small MoS2 nanoflake (edge length of 2.86 nm) is capable of penetrating the macrophage membrane independent of its concentration. We also demonstrate that when initiated with a corner point-on configuration, the surface-bound PEG chains of MoS2-PEG hinder its membrane insertion process, leading to a prolonged passage through the membrane. Moreover, when placed in a face-on arrangement initially, the MoS2-PEG exhibits a lower binding free energy than pristine MoS2 after its adsorption on the membrane surface. The PEG chains can even insert and get buried in the outer leaflet of the membrane, providing additional contact for membrane adsorption. Our flow cytometric experiments then show that the responses of macrophages to either MoS2-PEG or MoS2 are significantly higher than that of the control (no nanomaterial stimulus), with MoS2-PEG eliciting stronger cytokine secretion than the pristine MoS2. The characteristics of slower/prolonged membrane penetration and stronger membrane adsorption of MoS2-PEG compared to pristine MoS2 explain why it triggers more sustained stimulation and higher cytokine secretion in macrophages as observed in our experiments. Our findings reveal the underlying molecular mechanism of how MoS2-PEG influences the immune responses and suggest its potential applications in nanomedicine involving immune stimulation.

Z. Gu, S. H. Chen, Z. Ding, W. Song, W. Wei, S. Liu, G. Ma, and R. Zhou,The molecular mechanism of robust macrophage immune responses induced by PEGylated molybdenum disulfide, Nanoscale, 2019, 11, 22293-22304.

MoSBIOSENSOR

A non-enzymatic electrochemical biosensor based on Au@PBA(Ni-Fe):MoS2 nanocubes for stable and sensitive detection of hydrogen peroxide released from living cells

Hydrogen peroxide (H2O2) is the main product of enzymatic reactions and plays an important role in biological processes. The detection of H2O2 inside organisms or cells is critical. Here, we report a nickel-iron Prussian blue analogue nanocube doped with molybdenum disulfide and Au nanoparticles (Au@PBA(Ni-Fe):MoS2) as an electrochemical sensing material for the stable detection of H2O2 in neutral solutions for a long time. First, the Prussian blue analogue (PBA(Ni-Fe)) is synthesized by a simple charge-assembly technology, and then etched into PBA(Ni-Fe):MoS2 hollow nanocubes by a high-temperature hydrothermal reaction. Finally, Au nanoparticles are reduced inside the PBA(Ni-Fe):MoS2 in situ to generate Au@PBA(Ni-Fe):MoS2 nanocubes. Ni-doping enhances the nanocube's stability in neutral solutions; as a result, the sensor can maintain a stable current response towards H2O2 reduction for more than 1 h. The sensing material can meet the needs of a long-time test. The introduction of Au enhances the electron transfer efficiency, which endows the sensor with good reduction ability for H2O2 at 0 V over a wide linear range (0.5-200 muM and 210-3000 muM) and with a low detection limit (0.23 muM (S/N = 3)), which fulfills the requirements for the detection of H2O2 in a biological system. The sensor can sense H2O2 released from cells stimulated by ascorbic acid. Au@PBA(Ni-Fe):MoS2 provides good guidance for the future development of efficient biosensors to be applied in cell biology.

W. Zhang, C. Wang, L. Guan, M. Peng, K. Li, and Y. Lin,A non-enzymatic electrochemical biosensor based on Au@PBA(Ni-Fe):MoS2 nanocubes for stable and sensitive detection of hydrogen peroxide released from living cells, Journal of materials chemistry. B, 48, 2019.               

MoS2

Recent advances in synthesis and biosensors of two-dimensional MoS2

Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted tremendous research interests due to their exciting optical properties, large surface area, intercalatable morphologies and excellent electrochemically catalytic activity. Acting as the most typical member in TMDCs family, layer-dependent molybdenum disulfide (MoS2) with particular direct bandgap of 1.8 eV in monolayer has been widely applied in various biosensors with high sensitivity and selectivity. In this review, the preparation methods of MoS2, together with MoS2-based biosensors for detecting cells and biomolecules (such as glucose, DNA and antigens) would be summarized. In addition, the current challenges and future perspectives are outlined for the applications of biosensors based on 2D MoS2.

X. Zhu, R. Ding, Z. Wang, Y. Wang, X. Guo, Z. Song, Z. Wang, and M. Dong,Recent advances in synthesis and biosensors of two-dimensional MoS2, Nanotechnology, 2019, 30, 502004.

 

               

MoS2 human anion channel

Potential blockade of the human voltage-dependent anion channel by MoS2 nanoflakes

Despite significant interest in molybdenum disulfide (MoS2) nanomaterials, particularly in biomedicine, their biological effects have been understudied. Here, we explored the effect of MoS2 nanoflakes on the ubiquitous mitochondrial porin voltage-dependent anion channel (VDAC1), using a combined computational and functional approach. All-atomic molecular dynamics simulations suggest that MoS2 nanoflakes make specific contact interactions with human VDAC1. We show that the initial contacts between hVDAC1 and the nanoflake are hydrophobic but are subsequently enhanced by a complex interplay of van der Waals (vdW), hydrophobic and electrostatic interactions in the equilibrium state. Moreover, the MoS2 nanoflake can insert into the lumen of the hVDAC1 pore. Free-energy calculations computed by the potential of mean force (PMF) verify that the blocked configuration of the MoS2-hVDAC1 complex is more energetically favorable than the non-blocked binding mode. Consistent with these predictions, we showed that MoS2 depolarizes the mitochondrial membrane potential (Psim) and causes a decrease in the viability of mammalian tissue culture cells. These findings might shed new light on the potential biological effect of MoS2 nanomaterials.

Z. Gu, W. Song, S. Liu, B. Li, L. D. Plant, and X. Y. Meng,Potential blockade of the human voltage-dependent anion channel by MoS2 nanoflakes, Physical chemistry chemical physics : PCCP, 2019, 21, 9520-9530.

MoS2

MoS2 nano drug delivery

Drug Delivery System Based on Near-Infrared Light-Responsive Molybdenum Disulfide Nanosheets Controls the High-Efficiency Release of Dexamethasone To Inhibit Inflammation and Treat Osteoarthritis

Intra-articular injection has unique advantages in the treatment of osteoarthritis (OA), although it risks rapid clearance of the therapeutic drugs in the joint cavity. Combining therapeutic agents with functionalized nano carriers may provide an effective solution. Controlling the therapeutic concentration of the drug in the joint cavity through the drug-loading nanosystem can synergistically treat OA. Here, we proposed an intra-articular drug delivery nanosystem MoS2@CS@Dex (MCD), using the chitosan (CS)-modified molybdenum disulfide (MoS2) nanosheets as near-infrared (NIR) photo-responsive carriers, loaded with the anti-inflammatory drug dexamethasone (Dex). MCD responded to NIR light both in vitro and in vivo and triggered Dex release through photothermal conversion. This enabled the remote-controlled Dex release in the joint cavity by adjusting the radiation behavior of the NIR light. MCD prolonged the residence time of Dex in the joint cavity. The intra-articular injection of MCD in combination with NIR radiation ensured a significant increase in the therapeutic effect of Dex at low systemic doses, which attenuated the cartilage erosion in the OA caused by the secretion of inflammatory factors including TNF-alpha and IL-1 beta. The toxicity and side effects on other internal organs during metabolism were reduced in the body. In addition, the photoacoustic imaging capability of MoS2 nanosheets was used to detect the metabolism of MCD in the joint cavity. Our research indicated that MCD has great potential to treat OA.

Y. Y. Zhao, C. F. Wei, X. Chen, J. W. Liu, Q. Q. Yu, Y. A. Liu, and J. Liu,Drug Delivery System Based on Near-Infrared Light-Responsive Molybdenum Disulfide Nanosheets Controls the High-Efficiency Release of Dexamethasone To Inhibit Inflammation and Treat Osteoarthritis, Acs Applied Materials & Interfaces, 2019, 11, 11587-11601.

 

MoS2 synovial fluid

Fullerene-like MoS2 Nanoparticles as Cascade Catalysts Improving Lubricant and Antioxidant Abilities of Artificial Synovial Fluid

Intraarticular injection of hyaluronic acid (HA) for viscosupplementation is a nonsurgical therapy for osteoarthritis (OA). However, HA fails to lubricate under a significant load and tends to be depolymerized by the overproduction of reactive oxygen species (ROS) in inflammation. Here, we for the first time reported that fullerene-like MoS2 (F-MoS2) nanoparticles are efficient lubricants and antioxidants for artificial synovial fluid. A model of arthrosis was built, to evaluate the tribological behavior of F-MoS2 nanoparticles. The tests showed that they significantly improve the antiwear and friction-reducing abilities of the artificial synovial fluid. More importantly, the F-MoS2 nanoparticles possess intrinsic dual-enzyme-like activity, mimicking super- oxide dismutases (SOD) and catalases (CAT) under physiological conditions (pH 7.4, 25 degrees C). By coupling of these unique properties, a self-organized cascade catalytic system was constructed, which includes the disproportionation of superoxide radicals (O2 (center dot-)) to hydrogen peroxide (H2O2) and subsequently the disproportionation of H2O2 into oxygen (O2). The effectiveness of the detox system was evaluated by human umbilical vein endothelial cells (HUVEC) models exposed to oxidative stress. After that, F-MoS2 nanoparticles were used to regulate the ROS level in artificial synovial fluid containing HA. Relative viscosity measurements showed the excellent protective effect of F-MoS2 nanoparticles against HA oxidative damage offered by O2 (center dot-). These results indicate that F-MoS2 nanoparticles are promising candidates for treatment of OA and other diseases caused by lubrication deficiency or oxidative stress.

T. M. Chen, H. Zou, X. J. Wu, Y. Chen, S. T. Bo, L. Zheng, and G. W. Yang,Fullerene-like MoS2 Nanoparticles as Cascade Catalysts Improving Lubricant and Antioxidant Abilities of Artificial Synovial Fluid, ACS Biomaterials Science & Engineering, 2019, 5, 3079-3088.

 

MoS2 photothermal therapy

Nanoceria decorated flower-like molybdenum sulphide nanoflakes: an efficient nanozyme for tumour selective ROS generation and photo thermal therapy

We report nanoceria (NCeO2) decorated flower-like MoS2 nanoflakes as a nanozyme for cancer photothermal therapy (PTT). They exhibited enzyme-like activity for selectively killing tumor cells by ROS induction. The NCeO2 decoration significantly improved the photoconversion efficiencies (PCEs) of MoS2 nanoflakes when a NCeO2 concentration of -1 was used for synthesis. The novel material demonstrated here showed high photostability and PCE, without any systemic toxicity for cancer PTT.

C. Murugan, N. Murugan, A. K. Sundramoorthy, and A. Sundaramurthy,Nanoceria decorated flower-like molybdenum sulphide nanoflakes: an efficient nanozyme for tumour selective ROS generation and photo thermal therapy, Chemical communications (Cambridge, England), 2019.

 

 

Copper molybdate mineral

HUENITE, Cu4Mo3O12(OH)2, A NEW COPPER-MOLYBDENUM   OXY-HYDROXIDE MINERAL FROM THE SAN SAMUEL MINE, CARRERA PINTO, CACHIYUYO DE LLAMPOS DISTRICT, COPIAPO PROVINCE, ATACAMA REGION, CHILE

Huenite, Cu4Mo3O12(OH)2, is a new copper and molybdenum   oxy-hydroxide mineral found in the San Samuel Mine, Carrera Pinto, Cachiyuyo de Llampos district, Copiapo Province, Atacama Region, Chile. This new species forms flattened orthorhombic prisms up to 60-70 μm in size, weakly elongated along [001]. Huenite crystals were found on fractured surfaces of a quartz breccia, forming aggregates 1 mm in diameter in close association with lindgrenite, gypsum, dark grayish-brown tourmaline, and an unknown pale purple phase. The color is very dark reddish-brown, with a strong vitreous to adamantine luster. Its streak is pale reddish-brown to pinkish. The mineral is brittle with an irregular fracture and a Mohs hardness of 3.5-4 with a good cleavage on {010}. Its calculated density is 5.1 g/cm3. The calculated refractive index is 2.18. Huenite is non-fluorescent under 254 nm (short wave) and 366 nm (long, wave) ultraviolet light. The empirical formula, calculated on the basis of 3 (Mo+S+Si) atoms per formula unit, is (Cu3.519Fe0.4032+)(Sigma 3.922 .)(Mo2.907S0.003Si0.003)(Sigma 3.000)O-12 center dot(OH)(2.229), with H2O content calculated for a total of 100 wt.%. Huenite is trigonal, with space group P3(1)/c and unit-cell parameters a = 7.653(5) angstrom, c = 9.411(6) angstrom, and V= 477.4(5) angstrom(3) for Z= 2. The eight strongest measured powder X-ray diffraction lines are: [d in angstrom, (I/I-0), (hkl)]: 2.974 (100) (112), 1.712 (59.8) (132), 3.810 (50.6) (110), 2.702 (41.2) (022), 2.497 (38.1) (120), 1.450 (37.2) (134), 6.786 (24.9) (010), and 5.374 (24.5) (011). The mineral, which has been approved by the CNMNC under number IMA 2015-122, is named in honor of Edgar Huen.

P. Vignola, N. Rotiroti, G. D. Gatta, A. Risplendente, F. Hatert, D. Bersani, and V. Mattioli,HUENITE, Cu4Mo3O12(OH)(2), A NEW COPPER-MOLYBDENUM   OXY-HYDROXIDE MINERAL FROM THE SAN SAMUEL MINE, CARRERA PINTO, CACHIYUYO DE LLAMPOS DISTRICT, COPIAPO PROVINCE, ATACAMA REGION, CHILE, Canadian Mineralogist, 2019, 57, 467-474.

 

MoS2 biosensor

A supersensitive biosensor based on MoS2 nanosheet arrays for the real-time detection of H2O2 secreted from living cells

The fast and accurate real-time monitoring of hydrogen peroxide (H2O2) secreted from living cells plays a critical role in clinical diagnosis and management. Herein, we report low-cost and self-supported MoS2 nanosheet arrays for non-enzymatic eletrochemical H2O2 detection. Under the optimal test conditions, such MoS2 electrodes exhibit extremely promising electrocatalytic performance with a low detection limit of 1.0 μM (S/N = 3) and an excellent sensitivity of 5.3 mA mM-1 cm-2. Furthermore, the detection of the trace amount of H2O2 secreted from live A549 cancer cells was successfully performed with this biosensor.

H. Du, X. Zhang, Z. Liu, and F. Qu,A supersensitive biosensor based on MoS2 nanosheet arrays for the real-time detection of H2O2 secreted from living cells, Chemical communications (Cambridge, England), 2019, 55, 9653-9656.

MoS2

Oxidation of Nanodispersed MoS2 in Ambient Air: The Products and the Mechanistic Steps

Oxidation of finely divided molybdenum sulfide in ambient air has been studied for air exposure times from 10 min to 1 year to clarify the nature of the reaction products and the mechanistic steps. At the initial steps, for air exposure times from several minutes to several hours, rapid oxidation of MoS2 edges occurs with simultaneous formation of hydroxyl species and surface disulfide S22- moieties as attested by H-1 NMR, X-ray photoelectron spectra, and temperature-programmed reduction. Prolonged air exposure of MoS2 nanodispersions leads to deep oxidation. According to the results of X-ray absorption spectroscopy, UV-visible, and electron paramagnetic resonance spectroscopies, the main oxidation products are soluble paramagnetic molybdenum blue species and sulfuric acid. As shown by EXAS fitting, the major product is oxo-bridged dimolybdenyl Mo(V, VI) species. Ambient moisture plays an important role in the oxidation process as it contributes to the formation of sulfuric acid which leads to liquescence of the material and to deep oxidation without formation of a protective passivation layer.

P. Afanasiev, and C. Lorentz,Oxidation of Nanodispersed MoS2 in Ambient Air: The Products and the Mechanistic Steps, Journal of Physical Chemistry C, 2019, 123, 7486-7494.

 

MoS2 nano biosensors

Current and future envision on developing biosensors aided by 2D molybdenum disulfide (MoS2) productions

Two-dimensional (2D) layered nanomaterials have triggered an intensive interest due to the fascinating physiochemical properties with the exceptional physical, optical and electrical characteristics that transpired from the quantum size effect of their ultra-thin structure. Among the family of 2D nanomaterials, molybdenum disulfide (MoS2) features distinct characteristics related to the existence of direct energy bandgap, which significantly lowers the leakage current and surpasses other 2D materials. In this overview, we expatiate the novel strategies to synthesize MoS2 that cover techniques such as liquid exfoliation, chemical vapour deposition, mechanical exfoliation, hydrothermal reaction, and Van Der Waal epitaxial growth on the substrate. We extend the discussion on the recent progress in biosensing applications of the produced MoS2, highlighting the important surface-to-volume of ultrathin MoS2 structure, which enhances the overall performance of the devices. Further, envisioned the missing piece with the current MoS2-based biosensors towards developing the future strategies.

R. N. Dalila, M. K. M. Arshad, S. C. B. Gopinath, W. M. W. Norhaimi, and M. F. M. Fathil,Current and future envision on developing biosensors aided by 2D molybdenum disulfide (MoS2) productions, Biosensors & Bioelectronics, 2019, 132, 248-264.

 

MoS2 nano drug delivery

MoO3

ANTIBACTERIAL

Novel coating containing molybdenum oxide nanoparticles to reduce Staphylococcus aureus contamination on inanimate surfaces

We previously synthetized molybdenum oxide (MoO3) nanoparticles (NP) and showed their antibacterial activity against a representative collection of the most relevant bacterial species responsible for hospital-acquired infections, including Staphylococcus aureus. The aim of the present study was to prepare and characterize a novel coating with these MoO3 NP, confirm its mechanical stability, and investigate its biocidal effect to reduce S. aureus contamination on inanimate surfaces. In addition, the novel MoO3 NP coating was compared to a silver (Ag) NP coating synthetized by the same procedure. The MoO3 and Ag NP coatings were characterized in terms of their chemical structure by FT-IR, surface morphology by scanning electron microscopy, and mechanical properties by tensile and adhesion tests. The antimicrobial activity of the coatings was tested by following the loss of viability of S. aureus after 6h, 24h, 48h, and 72h exposure. MoO3 and Ag coatings exhibited surfaces of comparable morphologies and both presented elastomeric properties (tensile strength of ~420 kPa, Young's modulus of ~48 kPa, and maximum elongation of ~12%), and excellent (classification of 5B) adhesion to glass, steel and polystyrene surfaces. The two coatings exhibited a good antibacterial activity (R) against S. aureus over time (RMoO3 = 0.2-0.81; RAg = 0.61-2.37), although the effect of the Ag NP coating was more pronounced, especially at 72h (RMoO3 = 0.81 vs RAg = 2.37). Noteworthy, contrary to the Ag NP coating, the MoO3 NP coating was colourless and transparent, avoiding undesired unaesthetic effects. The synthetized coating with NP of MoO3, which has low toxicity to humans, capability of biodegradation, and rapid excretion, can be applied onto most standard materials and therefore is a promising tool to reduce S. aureus contamination on usual inanimate surfaces found in healthcare and community environments.

S. Picarra, E. Lopes, P. L. Almeida, H. de Lencastre, and M. Aires-de-Sousa,Novel coating containing molybdenum oxide nanoparticles to reduce Staphylococcus aureus contamination on inanimate surfaces, PLOS ONE, 2019, https://doi.org/10.1371/journal.pone.0213151

 

MoS2

ANTIFUNGAL

Molybdenum disulfide nanosheets loaded with chitosan and silver nanoparticles effective antifungal activities: in vitro and in vivo

A method was developed for the liquid exfoliation of molybdenum disulfide (MoS2) from its bulk materials using ultrasound in aqueous phase with the assistance of chitosan (CS) and silver nanoparticles (Ag NPs) for effective loading of a variety of therapeutic molecules. The characterization results revealed that the as-made chemically-exfoliated MoS2 nanosheets had an average thickness of approximately 10nm. The new material, CS and Ag NPs-modified MoS2 (MoS2-CS-Ag), showed highly effective antifungal activities against Saccharomyces uvarum and Aspergillus niger. The Ag NPs-loaded MoS2 nanosheets achieved outstanding antifungal effect by inhibiting fungal growth both in vitro and in vivo. Notably, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis of spore morphological changes caused by MoS2-CS-Ag treatment reveal that it may directly cause the cell death. The result of the analysis of the application of MoS2-CS-Ag as an antifungal for fruits also demonstrated the MoS2-CS-Ag protective properties against fungi. The excellent film-forming ability of CS has been shown to contribute to the effectiveness of MoS2-CS-Ag in preserving the freshness of fruits, exhibited in four chemical quality sections: Vc, total carbohydrate, weight loss, and titratable acidity in fruit preservation application assay. The present study reports a new and exciting insight in a multi-functional drug carrier for protecting postharvest fruit.

W. Zhang, Z. Mou, Y. Wang, Y. Chen, E. Yang, F. Guo, D. Sun, and W. Wang,Molybdenum disulfide nanosheets loaded with chitosan and silver nanoparticles effective antifungal activities: in vitro and in vivo, Materials science & engineering. C, Materials for biological applications, 2019, 97, 486-497.

 

TETRATHIOMOLYBDATE

DOGS LIVER DISEASE

 Ammonium tetrathiomolybdate treatment of copper-associated hepatopathy in dogs

Copper‐associated hepatopathy (CAH) is a common cause of liver disease in dogs. Although d‐penicillamine can be an effective treatment, some dogs fail treatment or develop adverse effects. Ammonium tetrathiomolybdate (TTM) has been used to treat pathologic copper accumulation in other species, but its therapeutic potential for CAH is unknown.

Objectives

To investigate short‐term safety and efficacy of TTM for treatment of CAH.

Animals

Ten dogs with CAH.

Methods

Prospective study. All dogs were treated with TTM PO [Per os, oral administration] for 6 weeks, and hepatic biopsies were performed after the treatment course. Dog experiencing initial decreases in hepatic copper concentrations ([Cu]H) received 6 additional weeks of TTM treatment and underwent 1 additional biopsy. Physical and laboratory examinations were performed every 2 weeks for study duration.

Results

Eight of 10 dogs had decreases in [Cu]H. Compared to baseline (median, 1606 μg/g; range, 572‐5158 μg/g), [Cu]H were decreased at 6 weeks (1033 μg/g, 450‐2975 μg/g; P = .04) and 12 weeks (931 μg/g, 218‐1677 μg/g; P = .02). Hepatic molybdenum concentrations increased >50‐fold (P < 0.001). Changes in histologic scores and hematologic and biochemical test results were variable and not significantly different from baseline. One dog developed presumed immune‐mediated anemia and thrombocytopenia, but it was unclear if this was related to TTM administration.

Conclusions and Clinical Importance

Results suggest that TTM can effectively decrease [Cu]H in some dogs with CAH. Larger studies are needed to determine the overall safety and efficacy of TTM for treating CAH and how it compares with current treatments.

D. K. Langlois, J. R. Querubin, W. D. Schall, N. C. Nelson, and R. C. Smedley,Ammonium tetrathiomolybdate treatment of copper-associated hepatopathy in dogs, Journal of veterinary internal medicine, 2019.  

https://doi.org/10.1111/jvim.15474

OPEN ACCESS

[“Copper storage hepatopathy is a condition caused by an abnormal accumulation of copper in the animal's liver, which leads to progressive damage and scarring of the liver (cirrhosis). This condition may be secondary to a primary disease or the result of genetic-based abnormal copper metabolism.”] https://www.petmd.com/dog/conditions/endocrine/c_multi_copper_storage_hepatopathy

 

CLUSTER ANTICANCER   

Cationic octahedral molybdenum cluster complexes functionalized with mitochondria-targeting ligands: photodynamic anticancer and antibacterial activities

Octahedral molybdenum cluster complexes have recently come forth as pertinent singlet oxygen photosensitizers towards biological applications. Still, their phototoxic efficiency in the absence of nanocarriers remains limited due to their poor cellular uptake. Here, two cationic octahedral molybdenum cluster complexes, bearing carboxylate ligands with triphenylphosphonium (1) or N-methyl pyridinium (2) mitochondria-targeting terminal functions, have been designed and synthesized. Their photophysical properties in water and in vitro biological activity were investigated in the context of blue-light photodynamic therapy of cancer and photoinactivation of bacteria. Upon blue light irradiation, complex 1 displays red luminescence with a quantum yield of 0.24 in water, whereas complex 2 is much less emissive (PhiL < 0.01). Nevertheless, both complexes efficiently produce singlet oxygen, O2(1Deltag). Complex 1 is rapidly internalized into HeLa cells and accumulated in mitochondria, followed by relocation to lysosomes and clearance at longer times. In contrast, the more hydrophilic 2 is not internalized into HeLa cells, highlighting the effect of the apical ligands on the uptake properties. The treatment with 1 results in an intensive phototoxic effect under 460 nm irradiation (IC50 = 0.10 +/- 0.02 muM), which exceeds by far those previously reported for octahedral cluster-based molecular photosensitizers. The ratio between phototoxicity and dark toxicity is approximately 50 and evidences a therapeutic window for the application of 1 in blue-light photodynamic therapy. Complex 1 also enters and efficiently photoinactivates Gram-positive bacteria Enterococcus faecalis and Staphylococcus aureus, documenting its suitability as a blue-light photosensitizer for antimicrobial applications.

K. Kirakci, J. Zelenka, M. Rumlova, J. Cvacka, T. Ruml, and K. Lang,Cationic octahedral molybdenum cluster complexes functionalized with mitochondria-targeting ligands: photodynamic anticancer and antibacterial activities, Biomaterials science, 2019, 7, 1386-1392.

ALLOY ANTIBACTERIAL

Electrochemical potential zone of viability on CoCrMo surfaces is affected by cell type: Macrophages under cathodic bias are more resistant to killing

Electrochemical interactions at the cell-metal interface determine cell viability and influence behavior in response to different electrode potential conditions, specifically cathodic biases. Mechanically assisted crevice corrosion, for example, induces cathodic potentials and the associated electrochemical consequences of increased reduction reactions at the implant surface may affect cell viability in a manner that is different for various cell phenotypes. Monocyte macrophage-like U937 cells were cultured on cobalt-chromium-molybdenum (CoCrMo) metal surfaces in vitro for 24 h to assess cell behavior in response to sustained applied voltages. The electrochemical zone of viability for U937 cells polarized for 24 h in vitro was -1000 Mo surfaces. It appears that cell phenotype directly influences behavior in response to cathodic electrochemical stimuli and that the monocyte macrophage-like cells are more resistant to cathodic potential stimuli than preosteoblasts. This may be due to a glutathione-based increased ability to quench reactive oxygen species and inflammatory-associated radicals hypothesized to be generated during reduction of oxygen. (c) 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 526-534, 2019.

M. J. Wiegand, G. W. Kubacki, and J. L. Gilbert,Electrochemical potential zone of viability on CoCrMo surfaces is affected by cell type: Macrophages under cathodic bias are more resistant to killing, Journal of biomedical materials research. Part A, 2019, 107, 526-534.

Destabilization of amyloid fibrils on interaction with  MoS2-based nanomaterials

The present work is motivated by the established concept that the structure and energetics of biomacromolecules can be modulated by confining their dimensions in the nanoscale. In particular, here we use force-field methods to understand the stability of amyloid fibrils at nanostructured interfaces, which can be useful for the development of new therapeutics for Alzheimer's disease. We explore the binding modes and structural properties of fibrils at the interface of  molybdenum  disulphide nanotubes and the nanosurface using classical molecular dynamics simulations. We find that in general the  MoS2 materials induces disruptions in the structure of the amyloid fibrils where the beta sheet conformation of the fibrils changes to a turned conformation, and it is large in the case of nanotubes in comparison to the nanosurfaces. The intermolecular hydrogen bonds, hydrophilic and hydrophobic contacts between the monomer peptides in the fibril are reduced due to their adsorption onto the  MoS2 materials, which results in a destabilization of the fibril. The destabilization of fibril is to some extent compensated for by the van der Waals interactions between the fibril and  MoS2. Overall the results indicate that  MoS2-based materials can be useful in inhibiting the aggregation of smaller protofibrils to matured fibrils and to bust the already formed fibrils. Therapeutic materials should not exhibit any cross interaction with other off-targets compounds. In order to test whether the  MoS2 nanomaterial has any such effect we have studied its interaction with two additional biomacromolecules, the human serum albumin and p53 protein, and we report no significant changes in the secondary structure of these biomolecules. Through molecular docking studies we also established that the drug binding ability of HSA is not altered by its surface binding to  MoS2 nanosurface.

S. K. Mudedla, N. A. Murugan, V. Subramanian, and H. Agren,Destabilization of amyloid fibrils on interaction with  MoS2-based nanomaterials, RSC Advances, 2019, 9, 1613-1624.

[Amyloid fibrils are peptide or protein aggregates that form under certain conditions in vitro or in vivo. For example, the amyloid fibril plaques found in brain tissue of Alzheimer patients are formed from the peptide Aβ and are associated with neurodegeneration. Amyloid formation is also observed with other diseases, such as type II diabetes and Creutzfeldt-Jakob disease. http://grigoriefflab.janelia.org/amyloid.]

 

Mechanistic understanding and binding analysis of two-dimensional MoS2 nanosheets with human serum albumin by the biochemical and biophysical approach

With the advent of molybdenum disulfide nanosheets ( MoS2 NSs) for biological applications, their complex interactions with human serum albumin (HSA) need to be understood in great detail for the molecular mechanisms of protein structure and activity. It was observed that  MoS2 NSs quench the intrinsic fluorescence of HSA as a consequence of ground-state complex formation by the electron transfer, van der Waals, and hydrophobic forces. The presence of  MoS2 NSs partly altered the conformation of HSA and destroyed the binding domain of HSA with bilirubin. In addition,  MoS2 NSs can decrease the rate of the formation of beta sheet structures of HSA, reduce the non-enzymatic glycosylation, and increase the esterase-like activity of HSA. We hope that the present study will be helpful to understand the fundamental interactions of the two-dimensional materials with various biomacromolecules in human blood.

H. Zhang, T. Zhang, and Y. Wang,Mechanistic understanding and binding analysis of two-dimensional  MoS2 nanosheets with human serum albumin by the biochemical and biophysical approach, Spectrochimica acta. Part A,  Molecular and biomolecular spectroscopy, 2019, 211, 18-25.

Synthesis of polyoxometalates, copper  molybdate (Cu3 Mo2O9) nanopowders, for energy storage applications

Synthesis of polyoxometalates (Cu3Mo2O9 nanopowders) was obtained by using solvothermal method and confirmed by X-ray diffraction pattern, with orthorhombic crystalline structure belonging to the space group Pna2(1)(33). Further, the synthesized Cu3Mo2O9 nanopowders were analyzed by using Raman, infrared, and photoluminescence studies. X-ray photoelectron spectroscopy study explained the oxidation states of  Mo-3d, Cu-2p, and O-1s in Cu3Mo2O9 nanopowders. Field emission scanning electron microscopy images clearly revealed the formation of nanostructure randomly oriented to form an interconnected rout, which emerged as a good candidate for storing more charges at the surface of Cu3Mo2O9 nanopowders. The electrochemical studies, such as cyclic voltammetry, electro impedance analysis, and galvanostatic charging-discharging studies, were used to analyze its electrochemical properties. To ensure the stability of Cu3Mo2O9 nanopowders, continuous charging and discharging studies were conducted for 1000 cycles at a current density of 5Ag(-1) and it exhibited good stability over a large number of cyclic studies with capacity retention of 99.2% after the first 500 cycles.

B. Saravanakumar, G. Ravi, R. Yuvakkumar, V. Ganesh, and R. K. Guduru,Synthesis of polyoxometalates, copper  molybdate (Cu3Mo2O9) nanopowders, for energy storage applications, Materials Science in Semiconductor Processing, 2019, 93, 164-172.

 

Molybdenum metal and commonly encountered molybdenum compounds

Molybdenum is widely distributed in nature. It is found in the minerals molybdenite,MoS2 which is the major ore of molybdenum, wulfenite, ferrimolybdate, jordisite, and powellite. Most molybdenum compounds are derived from molybdenum trioxide which is prepared by roasting molybdenum disulfide ores in air. Commonly used molybdenum-oxygen compounds are molybdenum trioxide, MoO3, sodium molybdate, Na2MoO4.2H2O, ammonium dimolybdate, (NH4)2 Mo2O7, and ammonium heptamolybdate, (NH4)6Mo7O24.4H2O.

Molybdenum is used mainly as an alloying element in steel, cast iron, and superalloys and in the electronics industries.

Leichtfried, G., in Ullmann's Encyclopedia of Industrial Chemistry ,5th ed. 1990, A16 , 668.

Molybdenum trioxide and molybdenum-oxygen compounds are added to steel and corrosion-resistant alloys. They are used in industrial catalysts, corrosion inhibitors, pigments, glass, ceramics, and enamels, flame retardant for polyester and polyvinyl chloride resins, as crop nutrients in agriculture, and as reagents in chemical analyses.

Vukasovich, M. S., in Ullmann's Encyclopedia of Industrial Chemistry ,5th ed., 1990, A16 , 682.

Molybdenum-sulfur compounds are used in lubrication to reduce friction and wear: molybdenum disulfide as a dry or suspended lubricant and molybdenum-sulfur complexes as soluble oil additives.

Mitchell, P. C. H., Wear , 1984, 100 , 281.

Other molybdenum compounds which find some application, for example, in the electronics industries and in chemical vapour deposition, are molybdenum pentachloride and molybdenum hexacarbonyl.

Environmental release of molybdenum compounds from industrial activities can occur in air (stack emissions), water (liquid effluents), or solid wastes (sludge): see Industrial and Environmental Exposure of Humans to Molybdenum.

Rubredoxins derivatives: Simple sulfur-rich coordination metal sites and its relevance for biology and chemistry

Rubredoxins (Rds) and their derivatives have been extensively used, in the last few decades, in order to elucidate structure and functional aspects of metal sites involving rich sulphur coordination spheres. The derivatives have been designed with two main purposes: (a) replacement of selective and specific amino acid residues in native systems by site direct mutagenesis, and (b) replacement of native metal ion (iron), producing novel metal sites. We will highlight in this review the key amino acid residues, recognized in native Rds, directly involved in electron transfer mechanisms. By protein template assisted synthesis, metal-substituted Rds are used as structural probes and bio-models. The tetra-cysteinyl metal coordination site in Rd has the surprising capacity of chelating a wide variety of metal ions (other than native iron), and this chemistry has been witnessing significant growth based on two main interests: (i) metals such as 57Fe, Zn, Co, Cd, Ga, In, and Hg were introduced and derivatives were synthesized in order to specifically probe structural determinants imposed by the protein, and (ii) Zn, Ni, Cu, as well as Mo (and most recently, W), were used with a particular interest: to model complex metal centres in sulphur-rich enzymes. The latter, in particular, is discussed in the context of Rd serving as a model complex of native enzymes, as well as the synthesis of small inorganic complexes. The review aims to bring synthetic biochemistry and synthetic inorganic chemistry together in a synergistic way. (C) 2017 Published by Elsevier B.V.

B. K. Maiti, R. M. Almeida, I. Moura, and J. J. G. Moura,Rubredoxins derivatives: Simple sulphur-rich coordination metal sites and its relevance for biology and chemistry, Coordination Chemistry Reviews, 2017, 352, 379-397.

 

Discovery, properties and applications of molybdenum and its compounds

The basic properties of molybdenum and subsequently the methods of producing metallic molybdenum are described. Selected classes of important inorganic compounds (molybdenum halides, molybdenum oxides, iso- and heteropolyoxomolybdates) as well as molybdenum hexacarbonyl and hybrid inorganic-organic materials are presented. Thereafter the focus is directed to various applications of metallic molybdenum, its alloys and compounds such as catalysts, lubricants and refractory ceramics. In conclusion, molybdenum's medicinal role and the antimicrobial activity of MoO3 and solid solutions MonW1-nO3 are discussed.

Lunk, H. J., and Hartl, H.,Discovery, properties and applications of molybdenum and its compounds, Chemtexts, 2017, 3.

MOLYBDENUM METAL ISOTOPES ALLOYS

ALLOY

Influence of Chromium-Cobalt-Molybdenum Alloy (ASTM F75) on Bone Ingrowth in an Experimental Animal Model

Cr-Co-Mo (ASTM F75) alloy has been used in the medical environment, but its use as a rigid barrier membrane for supporting bone augmentation therapies has not been extensively investigated. In the present study, Cr-Co-Mo membranes of different heights were placed in New Zealand white, male rabbit tibiae to assess the quality and volume of new bone formation, without the use of additional factors. Animals were euthanized at 20, 30, 40, and 60 days. Bone formation was observed in all of the cases, although the tibiae implanted with the standard membranes reached an augmentation of bone volume that agreed with the density values over the timecourse. In all cases, plasmatic exudate was found under the membrane and in contact with the new bone. Histological analysis indicated the presence of a large number of chondroblasts adjacent to the inner membrane surface in the first stages, and osteoblasts and osteocytes were observed under them. The bone formation was appositional. The Cr-Co-Mo alloy provides a scaffold with an adequate microenvironment for vertical bone volume augmentation, and the physical dimensions and disposition of the membrane itself influence the new bone formation.

J. Zuchuat, M. Berli, Y. Maldonado, and O. Decco,Influence of Chromium-Cobalt-Molybdenum Alloy (ASTM F75) on Bone Ingrowth in an Experimental Animal Model, Journal of functional biomaterials, 2017, 9.

Separation and purification of Tc-99m from Mo-99 produced by electron linear accelerator

The medical radionuclide Mo-99 was produced by the Mo-100(gamma,n) reaction using bremsstrahlung photons generated by an electron linear accelerator. The amount of Mo-99 produced was compared to that predicted by calculation using the particles and heavy ion transport code system. From the Mo-99 produced, highly pure Tc-99m was separated using the so-called technetium master milker, and the chemical yield of Tc-99m was 83-99 %. The installation of a new complex using this method and the electron linear accelerator with the preferable specification was suggested, and a possibility to supply the demand of Tc-99m was discussed and shown.

Sekimoto, S., Tatenuma, K., Suzuki, Y., Tsuguchi, A., Tanaka, A., Tadokoro, T., Kani, Y., Morikawa, Y., Yamamoto, A., and Ohtsuki, T.,Separation and purification of Tc-99m from Mo-99 produced by electron linear accelerator, Journal of Radioanalytical and Nuclear Chemistry, 2017, 311, 1361-1366.

 

ISOTOPE

Mo-99 Tc-99m

Evaluation of the radionuclidic product profiles of natural molybdenum irradiated using linear accelerator and nuclear reactor technology

The objective of this study was to compare the radionuclidic product profiles of the primary source Mo-99-sodium molybdate ((MoO4)-Mo-992-) solution obtained after dissolution of nuclear reactor-irradiated sintered molybdenum discs with the profiles obtained for linear accelerator-irradiated discs. Radionuclidic analysis was performed by high-purity germanium gamma-ray spectrometry. Samples were analyzed at multiple time points and radioactivity levels in order to observe short lived and low activity radionuclidic long-lived impurities. Results obtained showed that the radionuclidic profiles from the two technologies are consistent between samples, and are unique for either production technology.

Grigoryan, M., Fitzpatrick, J., and Mangera, K.,Evaluation of the radionuclidic product profiles of natural molybdenum irradiated using linear accelerator and nuclear reactor technology, Journal of Radioanalytical and Nuclear Chemistry, 2016, 310, 1195-1199.

MOLYBDENUM METAL CELLULAR RESPONSE

Cellular responses of osteoblast-like cells to 17 elemental metals

Elemental metals have been widely used to alloy metallic orthopedic implants. However, there is still insufficient research data elucidating the cell responses of osteoblastic cells to alloying elemental metals, which impedes the development of new metallic implant materials. In this study, the cellular responses of osteoblast-like cells (SaOS2) to 17 pure alloying elemental metals, that is, titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), manganese (Mn), iron (Fe), ruthenium (Ru), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), silicon (Si), and tin (Sn) were comparatively investigated in vitro. Cellular responses including intracellular total protein synthesis and collagen content, cell adhesion, cell proliferation, and alkaline phosphatase (ALP) activity on these elemental metals were systematically assessed and compared. It was found that these elemental metals could be categorized into three groups based on the cellular functions on them. Group 1, including Ti, Zr, Hf, Nb, Ta, Cr, Ru, and Si, showed excellent cell proliferation and varied ALP activity for SaOS2 cells. Cells exposed to Group 2, including Mo and Sn, although initially attached and grew, did not proliferate over time. In contrast, Group 3, including V, Mn, Fe, Co, Ni, Cu, and Zn, showed severe cytotoxicity toward SaOS2 cells. It is vital to consider the cell responses to the elemental metals when designing a new metallic implant material and the findings of this study provide insights into the biological performance of the elemental metals. (c) 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2016.

Zhang, D., Wong, C. S., Wen, C., and Li, Y.,Cellular responses of osteoblast-like cells to 17 elemental metals, Journal of biomedical materials research. Part A, 2016.

MOLYBDENUM ALLOYS BIOCOMPATIBILITY

Quantitative in vivo biocompatibility of new ultralow-nickel cobalt-chromium-molybdenum alloys

Nickel (Ni) eluted from metallic biomaterials is widely accepted as a major cause of allergies and inflammation. To improve the safety of cobalt-chromium-molybdenum (Co-Cr-Mo) alloy implants, new ultralow-Ni Co-Cr-Mo alloys with and without zirconium (Zr) have been developed, with Ni contents of less than 0.01%. In the present study, we investigated the biocompatibility of these new alloys in vivo by subcutaneously implanting pure Ni, conventional Co-Cr-Mo, ultralow-Ni Co-Cr-Mo, and ultralow-Ni Co-Cr-Mo with Zr wires into the dorsal sides of mice. After 3 and 7 days, tissues around the wire were excised, and inflammation; the expression of IL-1beta, IL-6, and TNF-alpha; and Ni, Co, Cr, and Mo ion release were analyzed using histological analyses, qRT-PCR, and inductively coupled plasma mass spectrometry (ICP-MS), respectively. Significantly larger amounts of Ni eluted from pure Ni wires than from the other wires, and the degree of inflammation depended on the amount of eluted Ni. Although no significant differences in inflammatory reactions were identified among new alloys and conventional Co-Cr-Mo alloys in histological and qRT-PCR analyses, ICP-MS analysis revealed that Ni ion elution from ultralow-Ni Co-Cr-Mo alloys with and without Zr was significantly lower than from conventional Co-Cr-Mo alloys. Our study, suggests that the present ultralow-Ni Co-Cr-Mo alloys with and without Zr have greater safety and utility than conventional Co-Cr-Mo alloys. (c) 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1505-1513, 2016.

Sonofuchi, K., Hagiwara, Y., Koizumi, Y., Chiba, A., Kawano, M., Nakayama, M., Ogasawara, K., Yabe, Y., and Itoi, E.,Quantitative in vivo biocompatibility of new ultralow-nickel cobalt-chromium-molybdenum alloys, Journal of orthopaedic research : official publication of the Orthopaedic Research Society, 2016, 34, 1505-13.

MOLYBDENUM METAL ALLOY BIOACCESSIBILITY

The European chemical framework REACH requires that hazards and risks posed by chemicals, including alloys and metals, that are manufactured, imported or used in different products (substances or articles) are identified and proven safe for humans and the environment. Metals and alloys need hence to be investigated on their extent of released metals (bioaccessibility) in biologically relevant environments. Read-across from available studies may be used for similar materials. This study investigates the release of molybdenum and iron from powder particles of molybdenum metal (Mo), a ferromolybdenum alloy (FeMo), an iron metal powder (Fe), MoO2, and MoO3 in different synthetic body fluids of pH ranging from 1.5 to 7.4 and of different composition. Spectroscopic tools and cyclic voltammetry have been employed to characterize surface oxides, microscopy, light scattering and nitrogen absorption for particle characterization, and atomic absorption spectroscopy to quantify released amounts of metals. The release of molybdenum from the Mo powder generally increased with pH and was influenced by the fluid composition. The mixed iron and molybdenum surface oxide of the FeMo powder acted as a barrier both at acidic and weakly alkaline conditions. These findings underline the importance of the surface oxide characteristics for the bioaccessibility of metal alloys.

Morsdorf, A.,Wallinder, I. O.,and Hedberg, Y.,Bioaccessibility of micron-sized powder particles of molybdenum metal, iron metal, molybdenum oxides and ferromolybdenum - Importance of surface oxides, Regul Toxicol Pharmacol, 2015.

A perspective on molybdenum biocompatibility and antimicrobial activity for applications in implants

The use of biomaterials has become routine in dentistry, reconstructive surgery of the locomotor system, treatment of congenital, traumatic and tumor situations, and knee or hip arthroplasty. The main issue related to metal biomaterials is the systemic release of metal ions and the related biological risks. When placed in contact with a living organism, they must meet a set of criteria: they must be biocompatible and biofunctional, as well as have the ability to produce a specific biological response at the surface, leading to the formation of a bond between the material and the receiving tissue and a surface texture which allows cell adhesion and bone growth; they must also provide adequate structure and mechanical strength, without causing adverse reactions in the surrounding physiological environment; they must not cause oncogenic effects; they must be easy to manipulate during surgery; and they must be amenable to visible imaging and sterilization.

The ability to use biomaterials is linked to the degree of biocompatibility and biofunctionality which in turn, are dependent on their physicochemical and mechanical properties, macroscopic and microscopic configuration, and the biological environment where they are deployed.

Metal alloys, particularly stainless steel, cobalt, molybdenum, chromium alloys, and titanium-based alloys find wide application in orthopedics for making joint replacement prostheses, systems for external or internal fixation of bone fractures, surgical correction of degenerative conditions, or in the composition of staples, screws, and wires. Any synthetic biomaterial can replace or restore the function of body tissues while maintaining a continuous or intermittent contact with the fluid. When in contact with the fluid, it is essential that materials be biocompatible, so they do not produce adverse biological responses or induce systemic effects. Thus, they must not be toxic, carcinogenic, mutagenic, or antigenic. Bioactive materials with antibacterial properties are also of significant medical interest. Materials exhibiting good antimicrobial activity that minimize the formation of biofilm without the risk of promoting the development of resistant microorganisms are desirable. In this respect, this review briefly summarizes the recent successes of this metal as a biocompatible material with antibacterial activity for biomedical applications.

Ribeiro, A. M., Flores-Sahagun, T. H. S., and Paredes, R. C.,A perspective on molybdenum biocompatibility and antimicrobial activity for applications in implants, Journal of Materials Science, 2016, 51, 2806-2816.

Thermodynamic properties

Thermodynamic properties for calcium molybdate, molybdenum tri-oxide and aqueous molybdate ion

The thermodynamic properties for CaMoO4(cr), MoO3(cr) and MoO42- (aq) were investigated. CaMoO4(cr) is the one of the host crystals of the yellow phases which are known as hygroscopic harmful phases in the nuclear fuel glasses. MoO3(cr) is the main component of the host crystals. MoO42- (aq) is the aqueous ion present in underground water after dissolution of the yellow phases. The standard molar entropies, Delta S-T(0)m degrees, at 298.15 K for CaMoO4(cr) and MoO3(cr) were determined by measuring their isobaric heat capacities, C degrees(p,m), from 2 K. Their standard Gibbs energies of formation, Delta(f)G(m)degrees, were determined by combining the Delta(T)(0) S-m degrees data with the reference data of the standard enthalpies of formation, Delta H-f(m)degrees. The standard electrochemical potential, E degrees, of MoO42- (aq) was determined from the thermodynamic cycle on the basis of thermodynamic properties obtained for CaMoO4(cr) and MoO3(cr). The unknown standard Gibbs energies of solution, Delta(sln)G(m)degrees, at 298.15 K for the actinide molybdates ThMo2O8(cr) and UMoO6(cr) were predicted from the presently obtained thermodynamic data for CaMoO4(cr), MoO3(cr) and MoO42 (aq). The obtained thermodynamic values are as follows: Delta(T)(0) S-m degrees (CaMoO4(cr), 298.15 K)/(J K (1) mol (1)) = 122.23 +/- 1.22. Delta(T)(0) S-m degrees(MoO3(cr), 298.15 K)/(J K (1) mol (1)) = 75.43 +/- 0.75. Delta(T)(0) S-m degrees (MoO42 (aq), 298.15 K)/(J K (1) mol (1)) = 32.25 +/- 4.41. Delta(f)G(m)degrees (CaMoO4(cr), 298.15 K)/(kJ mol (1)) = -1437.78 +/- 1.11. Delta(f)G(m)degrees (MoO3(cr), 298.15 K)/(kJ mol (1)) = -667.20 +/- 0.63. Delta(f)G(m)degrees(MoO42 (aq), 298.15 K)/(kJ mol (1)) = -836.61 +/- 1.02. E degrees (MoO42 (aq), 298.15 K)/V = 4.34 +/- 0.01. Delta(sln)G(m)degrees (ThMo2O8(cr), 298.15 K)/(kJ mol (1)) = 184.84 +/- 42.48. Delta(sln)G(m)degrees (UMoO6(cr), 298.15 K)/(kJ mol (1)) = 68.33 +/- 34.47. The present obtained data are expected to be useful for geo-chemical simulation of diffusion of radioactive elements through underground water. (C) 2017 Elsevier Ltd.

Morishita, M., Kinoshita, Y., Houshiyama, H., Nozaki, A., and Yamamoto, H.,Thermodynamic properties for calcium molybdate, molybdenum tri-oxide and aqueous molybdate ion, Journal of Chemical Thermodynamics, 2017, 114, 30-43.

MOLYBDENUM TRIOXIDE MoO3

MoO3

Methylene Blue-Fortified Molybdenum Trioxide Nanoparticles: Harnessing Radical Scavenging Property

A hybrid nanosystem with impeccable cellular imaging and antioxidant functionality is demonstrated. The microwave irradiation-derived molybdenum trioxide nanoparticles (MoO3 NPs) were surface-functionalized with the cationic dye molecule, methylene blue (MB), which enables superior UV-visible absorbance and fluorescence emission wavelengths potential for bioimaging. The radical scavenging property of the pristine MoO3 NPs and MoO3-MB NPs were studied in vivo using Caenorhabditis elegans as the model system. Heat shock-induced oxidative stress in C. elegans was significantly resolved by the MoO3-MB NPs, in agreement with the in vitro radical scavenging study by electron paramagnetic resonance spectroscopy. Hybrid nanostructures of MoO3-MB demonstrate synergistic benefits in intracellular imaging with intrinsic biocompatibility and antioxidant behavior, which can facilitate application as advanced healthcare materials toward bioimaging and clinical therapeutics.

M. Marimuthu, B. P. Kumar, L. M. Salomi, M. Veerapandian, and K. Balamurugan,Methylene Blue-Fortified Molybdenum Trioxide Nanoparticles: Harnessing Radical Scavenging Property, Acs Applied Materials & Interfaces, 2018, 10, 43429-43438.

MoO3

Antibacterial MoO3

Bactericidal efficacy of molybdenum oxide nanoparticles against antimicrobial-resistant pathogens

Multidrug-resistant bacteria pose a major threat to effective antibiotics and alternatives to fight multidrug-resistant pathogens are needed. We synthetized molybdenum oxide (MoO3) nanoparticles (NP) and determined their antibacterial activity against 39 isolates: (i) eight Staphylococcus aureus, including representatives of methicillin-resistant S. aureus epidemic clones; (ii) six enterococci, including vancomycin-resistant isolates; and (iii) 25 Gram-negative isolates (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacter cloacae), including extended spectrum beta-lactamases and carbapenemases producers. All isolates showed a MoO3 NP MIC of 700-800 mg l(-1). MoO3 NP produced a clear inhibition zone for S. aureus and all Gram-negative isolates at concentrations >/=25 mg ml(-1) and >/=50 mg ml(-1) for enterococci. When the NP solutions were adjusted to pH ~7, the biocidal activity was completely abolished. MoO3 NP create an acidic pH and show a universal antimicrobial activity against susceptible and resistant isolates belonging to the most relevant bacterial species responsible for hospital-acquired infections.

E. Lopes, S. Picarra, P. L. Almeida, H. de Lencastre, and M. Aires-de-Sousa,Bactericidal efficacy of molybdenum oxide nanoparticles against antimicrobial-resistant pathogens, Journal of medical microbiology, 2018.

MoO3
A Fully Biodegradable Battery for Self-Powered Transient Implants

Biodegradable transient devices represent an emerging type of electronics that could play an essential role in medical therapeutic/diagnostic processes, such as wound healing and tissue regeneration. The associated biodegradable power sources, however, remain as a major challenge toward future clinical applications, as the demonstrated electrical stimulation and sensing functions are limited by wired external power or wireless energy harvesters via near-field coupling. Here, materials' strategies and fabrication schemes that enable a high-performance fully biodegradable magnesium-molybdenum trioxide battery as an alternative approach for an in vivo on-board power supply are reported. The battery can deliver a stable high output voltage as well as prolonged lifetime that could satisfy requirements of representative implantable electronics. The battery is fully biodegradable and demonstrates desirable biocompatibility. The battery system provides a promising solution to advanced energy harvesters for self-powered transient bioresorbable implants as well as eco-friendly electronics.

X. Huang, D. Wang, Z. Yuan, W. Xie, Y. Wu, R. Li, Y. Zhao, D. Luo, L. Cen, B. Chen, H. Wu, H. Xu, X. Sheng, M. Zhang, L. Zhao, and L. Yin,A Fully Biodegradable Battery for Self-Powered Transient Implants, Small (Weinheim an der Bergstrasse, Germany), 2018, e1800994.

High efficient and selective removal of Pb2+ through formation of lead molybdate on alpha-MoO3 porous nanosheets array

2D hand-like structured alpha-MoO3 porous nanosheets were grown in-situ onto a capillary by a simple hydrothermal route, on which titanium dioxide seed layer was sol-dip-coated in advance. The alpha-MoO3 porous nanosheets array exhibits an exceptional lead ion uptake capacity up to 1450.0mg.g-1, and can effectively reduce Pb2+ concentration from 20mg.L-1 to a low level of smaller than 3mug.L-1, well below the acceptable limits in drinking water standards (10mug.L-1) and can efficiently remove 99.9% lead ion within a few minutes at room temperature. Furthermore, alpha-MoO3 porous nanosheets array also has high selectivity toward Pb2+ better than Cu2+, Zn2+, Cr3+ and Cd2+. The mechanism for adsorption was discussed according to the results of Zeta potential, IR, XPS and XRD analyses. The excellent removal performance of the array to Pb2+ is resulted from the electrostatic adsorption interaction and the formation of new species lead molybdate.

Wu, Y., Cheng, X., Zhang, X., Xu, Y., Gao, S., Zhao, H., and Huo, L.,High efficient and selective removal of Pb2+ through formation of lead molybdate on alpha-MoO3 porous nanosheets array, J Colloid Interface Sci, 2017, 491, 80-88.

 

Aqueous synthesis of molybdenum trioxide (h-MoO3, alpha-MoO3 H2O and h-/alpha-MoO3 composites) and their photochromic properties study

Molybdenum trioxide (h-MoO3, alpha-MoO3 H2O and h-/alpha-MoO3 composites) were prepared by a simple method in aqueous solution at 90-95 degrees C, without using autoclave or other complex equipment. The synthetic conditions for different phases of MoO3 were studied. The ratio of MoO42-:H+ and reaction temperature play important roles for the crystal phases of MoO3. By changing the amount of H+ ions, the samples can be controlled as h-MoO3 microrods or alpha-MoO3 H2O microbelts. h-/alpha-MoO3 composites in homogeneous structure were obtained at higher temperatures. The study on the transformation process of h-MoO3 ->alpha-MoO3 H2O ->alpha-MoO3 would be helpful in designing functional MoO3 materials. The h-MoO3 microrods and h-/alpha-MoO3 composites showed good photochromic behavior under sunlight irradiation. (C) 2016 Elsevier B.V. All rights reserved.

Song, Y. H., Zhao, Y., Huang, Z. F., and Zhao, J. Z.,Aqueous synthesis of molybdenum trioxide (h-MoO3, alpha-MoO3·H2O and h-/alpha-MoO3 composites) and their photochromic properties study, Journal of Alloys and Compounds, 2017, 693, 1290-1296.

Hydrogen reduction of molybdenum oxide at room temperature

The color changes in chemo- and photochromic MoO3 used in sensors and in organic photovoltaic (OPV) cells can be traced back to intercalated hydrogen atoms stemming either from gaseous hydrogen dissociated at catalytic surfaces or from photocatalytically split water. In applications, the reversibility of the process is of utmost importance, and deterioration of the layer functionality due to side reactions is a critical challenge. Using the membrane approach for high-pressure XPS, we are able to follow the hydrogen reduction of MoO3 thin films using atomic hydrogen in a water free environment. Hydrogen intercalates into MoO3 forming HxMoO3, which slowly decomposes into MoO2 +1/2 H2O as evidenced by the fast reduction of Mo6+ into Mo5+ states and slow but simultaneous formation of Mo4+ states. We measure the decrease in oxygen/metal ratio in the thin film explaining the limited reversibility of hydrogen sensors based on transition metal oxides. The results also enlighten the recent debate on the mechanism of the high temperature hydrogen reduction of bulk molybdenum oxide. The specific mechanism is a result of the balance between the reduction by hydrogen and water formation, desorption of water as well as nucleation and growth of new phases.

Borgschulte, A., Sambalova, O., Delmelle, R., Jenatsch, S., Hany, R., and Nuesch, F.,Hydrogen reduction of molybdenum oxide at room temperature, Sci Rep, 2017, 7, 40761.

MOLYBDENUM TRIOXIDE FILM      

Highly selective and sensitive response of 30.5 % of sprayed molybdenum trioxide (MoO3) nanobelts for nitrogen dioxide (NO2) gas detection

The molybdenum trioxide (MoO3) thin films have been successfully deposited onto the glass substrates using chemical spray pyrolysis (CSP) deposition technique at various substrate temperatures ranging from 300 degrees C to 450 degrees C with an interval of 50 degrees C. The effect of substrate temperature on the structural, morphological, optical and gas sensing properties of MoO3 thin films has been thoroughly investigated. X-ray diffraction analysis reveals that all the films have an orthorhombic crystal structure and are polycrystalline in nature. FE-SEM micrographs depict the formation of nanobelts-like morphology. AFM study reveals that the RMS surface roughness of MoO3 thin films increases from 8.6nm to 12nm with increase in substrate temperature from 300 degrees C to 400 degrees C and then decreases to 11.5nm for substrate temperature of 450 degrees C. Optical results show that the band gap of MoO3 thin films decreases from 3.92eV to 3.44eV. The selectivity studies show that the gas response of various gases varies as NH3222S2. Moreover, typical MoO3 film deposited at substrate temperature of 400 degrees C is highly selective and sensitive for detection of NO2 gas in comparison with other gases. The maximum response of 30.5 % is obtained towards 100ppm NO2 gas concentration at an operating temperature of 200 degrees C with response and recovery times of 20s and 160s, respectively. Finally, NO2 gas sensing mechanism model based on the chemisorption process is discussed.

Mane, A. A., Suryawanshi, M. P., Kim, J. H., and Moholkar, A. V.,Highly selective and sensitive response of 30.5 % of sprayed molybdenum trioxide (MoO3) nanobelts for nitrogen dioxide (NO2) gas detection, Journal of colloid and interface science, 2016, 483, 220-31.

Molybdenum Oxide Nanoparticles as Antimicrobial Agents

Molybdenum oxide nanoparticles were prepared by electrochemical reduction method using tetra ethyl ammonium bromide as structure directing agent in an organic medium tetrahydrofuran/acetonitrile in 4:1 ratio and at current density 14 mA/cm(2). The synthesized molybdenum oxide nanoparticles were characterized by using ultra violet-visible spectroscopy, infra red spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and transmission electron microscope analysis techniques. The nanoparticles were tested for antibacterial activity against human pathogens like gram negative Escherichia coli, Salmonella typhi and gram positive Staphylococcus aureus, Bacillus subtilis strains, which showed excellent antibacterial properties.

Dighore, N., Jadhav, S., Anandgaonker, P., Gaikwad, S., and Rajbhoj, A.,Molybdenum Oxide Nanoparticles as Antimicrobial Agents, Journal of Cluster Science, 2017, 28, 109-118.

MoO3 ANTIMICROBIAL

Cellulose acetate based composites with antimicrobial properties from embedded molybdenum trioxide particles

The objective of this research is to develop novel cellulose acetate (biopolymer) composite materials with an excellent antimicrobial activity by embedding molybdenum trioxide particles with unique high specific surface area.

High surface area molybdenum trioxide particles were prepared from freshly precipitated molybdenum trioxide dihydrate (MoO3 x2H2 O) and subsequent calcination at 340 degrees C under H2 /N2 gas.

Microbiological evaluation against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa were performed applying a roll-on test and excellent antimicrobial activities were determined for composites with embedded anhydrous molybdenum trioxide with a high specific surface area.

Cellulose acetate composites comprising MoO3 particles can eliminate three harmful bacteria as a result of the release of protons from the material and surface enlargement of the molybdenum trioxide particles.

The findings support a proposed antimicrobial mechanism based on local acidity increase due to large specific surface areas. This article is protected by copyright. All rights reserved.

Shafaei, S., Dorrstein, J., Guggenbichler, J. P., and Zollfrank, C.,Cellulose acetate based composites with antimicrobial properties from embedded molybdenum trioxide particles, Letters in applied microbiology, 2016.

 

MoO3 STRUCTURE

The crystallographic structure and morphology of redox active transition metal oxides have a pronounced effect on their electrochemical properties. In this work, h-MoO3 nanostructures with three distinct morphologies, i.e., pyramidal nanorod, prismatic nanorod and hexagonal nanoplate, were synthesized by a facile solvothermal method. The morphologies of h-MoO3 nanostructures were tailored by a controlled amount of hexamethylenetetramine. An enhanced specific capacitance about 230 F g(-1) at an applied current density of 0.25 A g(-1) was achieved in h-MoO3 pyramidal nanorods. Electrochemical studies confirmed that the h-MoO3 pyramidal nanorods exhibit superior charge-storage ability. This improved performance can be ascribed to the coexistence of its well exposed crystallographic planes with abundant active sites, i.e., hexagonal window (HW), trigonal cavity (TC) and four-coordinated square window (SW). The mechanism of charge-storage is likely facilitated by the vehicle mechanism of proton transportation due to the availability of the vehicles, i.e., NH4(+) and H2O. The promising, distinct and unexploited features of h-MoO3 nanostructures reveal a strong candidate for pseudocapacitive electrode materials.

Kumar, V., Wang, X., and Lee, P. S.,Formation of hexagonal-molybdenum trioxide (h-MoO3) nanostructures and their pseudocapacitive behavior, Nanoscale, 2015, 7, 11777.

 

Influence of calcination temperature on the structural and photochromic properties of nanocrystalline MoO3

Nanocrystalline metastable hexagonal and thermodynamically stable orthorhombic MoO3were successfully synthesized by precipitation, and calcined at various temperatures in the range 200-500 degrees C.

The influence of calcination temperature on crystal structure, crystallite size, thermal properties, morphology, optical properties, and photochromic properties was determined.

The 432 degrees C phase transformation temperature of hexagonal flower-like MoO3to an orthorhombic platelet structure was determined.

The band gap energy of MoO3 varied from 3.13 to 3.20 eV, depending on calcination temperature.

The photochromic properties were determined with UV irradiation and CIE Lab colour system. The hexagonal MoO3 from low temperature calcination had an about seven-fold photochromic efficiency relative to orthorhombic MoO3.

Jittiarporn, P., Sikong, L., Kooptarnond, K., and Taweepreda, W.,INFLUENCE OF CALCINATION TEMPERATURE ON THE STRUCTURAL AND PHOTOCHROMIC PROPERTIES OF NANOCRYSTALLINE MoO3, Digest Journal of Nanomaterials and Biostructures, 2015, 10, 1237-1248.

 

Band energy control of molybdenum oxide by surface hydration

The application of oxide buffer layers for improved carrier extraction is ubiquitous in organic electronics. However, the performance is highly susceptible to processing conditions. Notably, the interface stability and electronic structure is extremely sensitive to the uptake of ambient water.

In this study we use density functional theory calculations to asses the effects of adsorbed water on the electronic structure of MoOx, in the context of polymer-fullerene solar cells based on PCDTBT. We obtain excellent agreement with experimental values of the ionization potential for pristine MoO3 (010). We find that IP and EA values can vary by as much as 2.5 eV depending on the oxidation state of the surface and that adsorbed water can either increase or decrease the IP and EA depending on the concentration of surface water. (C) 2015 AIP Publishing LLC.

Butler, K. T., Crespo-Otero, R., Buckeridge, J., Scanlon, D. O., Bovill, E., Lidzey, D., and Walsh, A.,Band energy control of molybdenum oxide by surface hydration, Applied Physics Letters, 2015, 107.

Oxygen deficiency in MoO3 polycrystalline nanowires and nanotubes

We report on the synthesis of polycrystalline molybdenum oxide (MoO3) nanowires via oxidation of molybdenum-sulfur-iodine (Mo6S2I8) nanowires. This unique synthesis route results in an interesting morphology comprising porous nanowires and nanotubes.

We found the nanowires to have the orthorhombic MoO3 structure. The structure is slightly oxygen deficient which results in the appearance of a new resonant Raman band (1004 cm-1) and paramagnetic defects (Mo5+) of both the point and crystallographic shear plane nature. (C) 2015 Elsevier B.V. All rights reserved.

Varlec, A., Arcon, D., Skapin, S. D., and Remskar, M.,Oxygen deficiency in MoO3 polycrystalline nanowires and nanotubes, Materials Chemistry and Physics, 2016, 170, 154-161.

Probing edge-activated resonant Raman scattering from mechanically exfoliated 2D MoO3 nanolayers

We report spatially resolved vibrational analysis of mechanically exfoliated single-crystalline alpha-MoO3 nanolayers.

Raman scattering from alpha-MoO3 was enhanced predominantly at the outside edges of the nanolayers. The enhanced Raman scattering at the edges was attributed primarily to the enhanced resonant Raman effect caused by a high density of oxygen vacancies localized at the edges.

The localized vacancy sites corresponded to a non-stoichiometric phase of MoO3, which would provide reactive sites with high catalytic activity.

Yano, T. A., Yoshida, K., Hayamizu, Y., Hayashi, T., Ohuchi, F., and Hara, M.,Probing edge-activated resonant Raman scattering from mechanically exfoliated 2D MoO3 nanolayers, 2d Materials, 2015, 2.

Nanoscale Insights into the Hydrogenation Process of Layered alpha-MoO3

The hydrogenation process of the layered alpha-MoO3 crystal was investigated on a nanoscale.

At low hydrogen concentration, the hydrogenation can lead to formation of HxMoO3 without breaking the MoO3 atomic flat surface. For hydrogenation with high hydrogen concentration, hydrogen atoms accumulated along the < 101 > direction on the MoO3, which induced the formation of oxygen vacancy line defects. The injected hydrogen atoms acted as electron donors to increase electrical conductivity of the MoO3.

Near-field optical measurements indicated that both of the HxMoO3 and oxygen vacancies were responsible for the coloration of the hydrogenated MoO3, with the latter contributing dominantly.

On the other hand, diffusion of hydrogen atoms from the surface into the body of the MoO3 will encounter a surface diffusion energy barrier, which was for the first time measured to be around 80 meV. The energy barrier also sets an upper limit for the amount of hydrogen atoms that can be bound locally inside the MoO3 via hydrogenation.

We believe that our findings has provided a clear picture of the hydrogenation mechanisms in layered transition-metal oxides, which will be helpful for control of their optoelectronic properties via hydrogenation.

Xie, W. G., Su, M. Z., Zheng, Z. B., Wang, Y., Gong, L., Xie, F. Y., Zhang, W. H., Luo, Z., Luo, J. Y., Liu, P. Y., Xu, N. S., Deng, S. Z., Chen, H. J., and Chen, J.,Nanoscale Insights into the Hydrogenation Process of Layered alpha-MoO3, Acs Nano, 2016, 10, 1662-1670.

A theoretical study of stability and vacancy replenishing of MoO3(010) surfaces in oxygen atmosphere

Oxygen vacancies on transition metal oxide surfaces are catalytically very important. The stability, shape and replenishing process of the vacancies are critical to understanding reactions happening on the surfaces.

In this paper we investigate the stability of various defective MoO3 (0 1 0) surfaces and examine the influence of environmental oxygen on the stability as well as the active sites for the replenishing process.

Our calculations reveal that the line oxygen defect along a (asymmetric oxygen) direction is thermodynamically most favorable at higher defect concentration whereas point defect surfaces are unfavorable. Under normal experimental conditions the perfect surface dominates the MoO3 (0 1 0).

We show that for stoichiometric surfaces of any oxides (A(x)O(y)) the formation energy per vacancy controls the favorable defect shape (line or point defects). Calculations indicate that O-2 can dissociate readily on the surfaces that double vacancies share one Mo atom. The replenishing process of the oxygen vacancies through O-2 dissociation most likely occurs on the double-vacancy containing one terminal and one asymmetrical oxygen vacancies. (C) 2015 Elsevier B.V. All rights reserved.

Lei, Y. H., and Chen, Z. X.,A theoretical study of stability and vacancy replenishing of MoO3(010) surfaces in oxygen atmosphere, Applied Surface Science, 2016, 361, 107-113.

Facile synthesis of a green metastable MoO3 for the selective oxidation of methanol to formaldehyde

Metastable MoO3 was successfully synthesized by a chemical transformation of alpha-MoO3 and characterized by TG-DSC, BET, XRD and Raman spectroscopy. The prepared material was highly active and selective to formaldehyde formation from methanol over a wide range of reaction temperatures. The formaldehyde selectivity can reach up to 99 % at about 98 % methanol conversion. The stability of the prepared catalysts was also investigated.

Phuong, P. T. T., Duy, N. P. H., Tai, V. T., Huan, N. M., Phuc, N. H. H., and Loc, L. C.,Facile synthesis of a green metastable MoO3 for the selective oxidation of methanol to formaldehyde, Reaction Kinetics Mechanisms and Catalysis, 2016, 117, 161-171.

Isoprenoid Alcohols are Susceptible to Oxidation with Singlet Oxygen and Hydroxyl Radicals

Isoprenoids, as common constituents of all living cells, are exposed to oxidative agents-reactive oxygen species, for example, singlet oxygen or hydroxyl radicals. Despite this fact, products of oxidation of polyisoprenoids have never been characterized.

In this study, chemical oxidation of isoprenoid alcohols (Prenol-2 and -10) was performed using singlet oxygen (generated in the presence of hydrogen peroxide/molybdate or upon photochemical reaction in the presence of porphyrin), oxygen (formed upon hydrogen peroxide dismutation) or hydroxyl radical (generated by the hydrogen peroxide/sonication, UV/titanium dioxide or UV/hydrogen peroxide) systems.

The structure of the obtained products, hydroxy-, peroxy- and heterocyclic derivatives, was studied with the aid of mass spectrometry (MS) and nuclear magnetic resonance (NMR) methods. Furthermore, mass spectrometry with electrospray ionization appeared to be a useful analytical tool to detect the products of oxidation of isoprenoids (ESI-MS analysis), as well as to establish their structure on the basis of the fragmentation spectra of selected ions (ESI-MS/MS analysis). Taken together, susceptibility of polyisoprenoid alcohols to various oxidizing agents was shown for the first time.

Komaszylo Nee Siedlecka, J., Kania, M., Masnyk, M., Cmoch, P., Lozinska, I., Czarnocki, Z., Skorupinska-Tudek, K., Danikiewicz, W., and Swiezewska, E.,Isoprenoid Alcohols are Susceptible to Oxidation with Singlet Oxygen and Hydroxyl Radicals, Lipids, 2016, 51, 229-44.

Degradable Molybdenum Oxide Nanosheets with Rapid Clearance and Efficient Tumor Homing Capabilities as a Therapeutic Nanoplatform

Molybdenum oxide (MoOx) nanosheets with high near-infrared (NIR) absorbance and pH-dependent oxidative degradation properties were synthesized, functionalized with polyethylene glycol (PEG), and then used as a degradable photothermal agent and drug carrier.

The nanosheets, which are relatively stable under acidic pH, could be degraded at physiological pH. Therefore, MoOx-PEG distributed in organs upon intravenous injection would be rapidly degraded and excreted without apparent in vivo toxicity. MoOx-PEG shows efficient accumulation in tumors, the acidic pH of which then leads to longer tumor retention of those nanosheets.

Along with the capability of acting as a photothermal agent for effective tumor ablation, MoOx-PEG can load therapeutic molecules with high efficiencies.

This concept of inorganic theranostic nanoagent should be relatively stable in tumors to allow imaging and treatment, while being readily degradable in normal organs to enable rapid excretion and avoid long-term retention/toxicity.

Song, G., Hao, J., Liang, C., Liu, T., Gao, M., Cheng, L., Hu, J., and Liu, Z.,Degradable Molybdenum Oxide Nanosheets with Rapid Clearance and Efficient Tumor Homing Capabilities as a Therapeutic Nanoplatform, Angewandte Chemie (International ed. in English), 2016, 55, 2122-6.

MOLYBDATES AND POLYMOLYBDATES

Silver-, calcium-, and copper molybdate compounds: Preparation, antibacterial activity, and mechanisms

Developing novel compounds with antimicrobial properties can be an effective approach to decreasing the number of healthcare-associated infections, particularly in the context of medical devices and touch surfaces. A variety of molybdate powders (Ag2MoO4, CaMoO4, CuMoO4 and Cu3Mo2O9) were synthesized and characterized, and Escherichia coli was used as a model gram-negative bacterium to demonstrate their antimicrobial properties. Optical density measurements, bacterial colony growth, and stained gel images for protein expression clearly showed that silver- and copper molybdates inhibit bacterial growth, whereas CaMoO4 exhibited no bactericidal effect. All tests were performed in both daylight and darkness to assess the possible contribution of a photocatalytic effect on the activity observed. The main mechanism responsible for the antibacterial effect observed for Ag2MoO4 is related to Ag(+) release in combination with medium acidification, whereas for compounds containing copper, leaching of Cu(2+) ions is proposed. All these effects are known to cause damage at the cellular level. A photocatalytic contribution to the antibacterial activity was not clearly observable. Based on the pH and solubility measurements performed for powders in contact with various media (ultrapure water and bacterial growth medium), silver molybdate (Ag2MoO4) was identified as the best antibacterial candidate. This compound has great potential for further use in hybrid powder-polymer/varnish systems for touch surfaces in healthcare settings.

Tanasic, D., Rathner, A., Kollender, J. P., Rathner, P., Muller, N., Zelenka, K. C., Hassel, A. W., and Mardare, C. C.,Silver-, calcium-, and copper molybdate compounds: Preparation, antibacterial activity, and mechanisms, Biointerphases, 2017, 12, 05g607.

Synthesis, characterization, density functional theory studies and antibacterial activity of a new Schiff base dioxomolybdenum(VI) complex with tryptophan as epoxidation catalyst

A cis-dioxomolybdenum(VI) complex was prepared with MoO2(acac)2 and a Schiff base ligand (2-((2-hydroxybenzylidene)amino)-3-(1H-indol-3-yl)propanoic acid) derived from salicylaldehyde and l-tryptophan in ethanol and designated as [MoO2(Sal-Tryp)(EtOH)]. It was characterized using several techniques including thermogravimetric and elemental analyses and mass, Fourier transform infrared and UV-visible spectroscopies. Theoretical calculations were performed using density functional theory for studying the molecular structure. An in vitro antibacterial activity evaluation showed that [MoO2(Sal-Tryp)EtOH] complex exhibits good inhibitory effects against Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria in comparison to standard antibacterial drugs. It was also found that [MoO2(Sal-Tryp)EtOH] complex successfully catalyses the epoxidation of cyclooctene, norbornene, cyclohexene, styrene, -methylstyrene and trans-stilbene, with 45-100% conversions and 64-100% selectivities. Based on the obtained results, the heterogeneity and reusability of the catalyst seem promising.

Asgharpour, Z., Farzaneh, F., Ghiasi, M., and Azarkish, M.,Synthesis, characterization, density functional theory studies and antibacterial activity of a new Schiff base dioxomolybdenum(VI) complex with tryptophan as epoxidation catalyst, Applied Organometallic Chemistry, 2017, 31.

Antibacterial

beta-Ag2MoO4 microcrystals: Characterization, antibacterial properties and modulation analysis of antibiotic activity

This study reports the antibacterial properties and modulation analysis of antibiotic activity by beta-Ag2MoO4 microcrystals as well as their structural and vibrational characterization.

The silver molybdate was obtained by the conventional hydrothermal method, and the structural, vibrational and morphological properties of the sample were determined using X-ray diffraction, Raman spectroscopy and scanning electron microscopy images. beta-Ag2MoO4 microcrystals obtained show spinel-type cubic structure (Fd-3m) with irregular shapes.

The evaluation of antibacterial and modulatory-antibiotic activity was performed using the microdilution method to determine the Minimum Inhibitory Concentration (MIC) of the beta-Ag2MoO4 and antibiotics alone and associated with the silver molybdate.

The beta-Ag2MoO4 modulates the antibiotic activity against all bacteria assayed in a synergistic (as the norfloxacin and gentamicin against S. aureus and gentamicin against E. coli) or an antagonistic form (as the norfloxacin against E.coli and P. aeruginosa).

The reversion of antibiotic resistance by combinations with Ag2MoO4 could be a novel strategy to combat infections caused by multiple drug resistance (MDR) pathogens.

Our results indicate that these silver molybdates present a clinically relevant antibacterial activity and enhanced the antibiotic activity of some antibiotics against MDR strain of S. aureus and E. coli, being an interesting alternative to combat antibiotic-resistant bacterial infectious agents.

Moura, J. V., Freitas, T. S., Cruz, R. P., Pereira, R. L., Silva, A. R., Santos, A. T., da Silva, J. H., Luz-Lima, C., Freire, P. T., and Coutinho, H. D.,beta-Ag2MoO4 microcrystals: Characterization, antibacterial properties and modulation analysis of antibiotic activity, Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 2017, 86, 242-247.

Novel application of simple molybdates: Catalytic hydrolysis of an organophosphate neurotoxin under mild aqueous conditions

A novel protocol for hydrolyzing phosphonothioate neurotoxins has been developed that uses a readily available, inexpensive and non-toxic molybdate (MoO42-). The target organophosphate is O,S-diethylphenyl phosphonothioate (1), a model compound that has served as an analog of the chemical warfare agent VX. Molybdate-mediated hydrolysis of 1 proceeds at room temperature (pH similar to 7.5) and yields a relatively safe phosphonate product through P-S specific scission. This is the first report of utilizing the molybdateMoO42- , to degrade an organophosphate neurotoxin with turnover. A ΔS  of 81.5 J/mol.K (-19.5 cal/mol.K) indicates a bimolecular process, and O-18-labeling studies show no oxygen exchange of 1 throughout the hydrolysis by MoO42- (aq). We hypothesize primarily the monomeric molybdate is the active species at pH 7.5 where a S(N)2(P) mechanism takes place. Density functional theory methods suggest the molybdate oxoanion serves as the nucleophile to attack phosphonothioate 1 to form a molybdate-phosphonate anhydride that subsequently hydrolyzes to the starting molybdate and phenylethyl phosphonate. (C) 2017 Elsevier B.V. All rights reserved.

Kuo, L. Y., Dill, K. M., Shari'ati, Y. A., Bright, E. K., and McCormick, T.,Novel application of simple molybdates: Catalytic hydrolysis of an organophosphate neurotoxin under mild aqueous conditions, Inorganica Chimica Acta, 2017, 466, 1-7.

NEW PROMISING ANTIFOULING AGENT BASED ON POLYMERIC BIOCIDE POLYHEXAMETHYLENE GUANIDINE MOLYBDATE

A new polymeric biocide polyhexamethylene guanidine (PHMG) molybdate has been synthesized. The obtained cationic polymer has limited water solubility of 0.015 g/100mL and is insoluble in paint solvents. The results of acute toxicity studies indicate moderate toxicity of PHMG molybdate, which has a median lethal dose at 48 h of 0.7 mg/L for Daphnia magna and at 96 h of 17 mg/L for Danio rerio (zebrafish) freshwater model organisms. Commercial ship paint was then modified by the addition of a low concentration of polymeric biocide 5% (w/w). The painted steel panels were kept in Dnipro River water for the evaluation of the dynamics of fouling biomass. After 129-d exposure, Bryozoa dominated in biofouling of tested substrates, forming 86% (649 g/m(2)) of the total biomass on control panel surfaces. However, considerably lower Bryozoa fouling biomass (15 g/m(2)) was detected for coatings containing PHMG molybdate. Dreissenidae mollusks were found to form 88% (2182 g/m(2)) of the fouling biomass on the control substrates after 228 d of exposure, whereas coatings containing PHMG molybdate showed a much lower biomass value of 23.6 g/m(2). The leaching rate of PHMG molybdate in water was found to be similar to rates for conventional booster biocides ranging from 5.7 mg/cm(2)/d at the initial stage to 2.2mg/cm(2)/d at steady state. (C) 2017 SETAC

Protasov, A., Bardeau, J. F., Morozovskaya, I., Boretska, M., Cherniavska, T., Petrus, L., Tarasyuk, O., Metelytsia, L., Kopernyk, I., Kalashnikova, L., Dzhuzha, O., and Rogalsky, S.,NEW PROMISING ANTIFOULING AGENT BASED ON POLYMERIC BIOCIDE POLYHEXAMETHYLENE GUANIDINE MOLYBDATE, Environmental toxicology and chemistry, 2017, 36, 2543-2551.

 

Redox and ligand binding reactivity in iron and chromium -substituted polyoxometalates

Using UV-vis and EPR (electron paramagnetic resonance) spectroscopy, iron- and chromium- substituted polyoxometalates were shown to undergo controlled reduction, involving the iron and chromium as well as the molybdenum/tungsten framework; furthermore, reoxidation was also shown to be possible with molecular oxygen or hydrogen peroxide in a cycle reminiscent of iron-containing enzymes. The influence of pH, ligands and/or potential redox agents such as imidazole, thiocyanate, thiosulfate, mercaptoethanol and ascorbate were examined.

Kakes, M., Cioloboc, D., Tomsa, A. R., Silaghi-Dumitrescu, R., and Damian, G.,REDOX AND LIGAND BINDING REACTIVITY IN IRON AND CHROMIUM -SUBSTITUTED POLYOXOMETALATES, Revue Roumaine De Chimie, 2015, 60, 707-720.

Quantitative measurement of Bronsted acidity by TPD of ammonia on H3 PMo12O40 and its Cs1 salt, in bulk and supported on SBA-15

The method for acidity measurement through temperature programmed desorption (TPD) of ammonia was adapted for simultaneous TG/DTG-DTA analysis of the H-3[PMo12O40] and its Cs acid salts, in bulk and supported on SBA-15 support. The desorption of NH3 consists of the NH3 and H2O release in steps as a result of temperature increase. The last step corresponds to expelling of NH3 by decomposition of species strong bonded like the ammonium cation, simultaneously with constitutive water, within the 300-600 A degrees C range. The MS analysis showed that the oxidation of ammonia to N2O and NO during desorption had occurred simultaneously with reduction of Mo6+. The reoxidation of samples with air in all cases was done finally. In order to separate the water release (water formed by condensation of hydroxyl groups belonging to SBA-15) from the ammonia desorption for supported samples, a TPD of H2O was done for every sample. In the case of pure compounds, the mass loss corresponding to the last stage of desorption (after correction with the mass loss as a result of reduction, equal with the mass increase owing to the reoxidation) gives the amounts of NH3 and constitutive water, which correspond stoichiometrically with the Bronsted acidity. The subtraction of mass loss for TPD of water from the corrected mass loss for TPD of ammonia and water (because of the mass loss as a result of the reduction) gives the amount of NH3 corresponding stoichiometrically with the Bronsted acidity. The acidic strength was estimated on the basis of the temperatures for the DTG peaks.

Sasca, V. Z., Popa, A., and Verdes, O.,Quantitative measurement of Bronsted acidity by TPD of ammonia on H-3 PMo12O40 and its Cs1 salt, in bulk and supported on SBA-15, Journal of Thermal Analysis and Calorimetry, 2016, 123, 557-569.

MOLYBDATE STRUCTURE

Time-of-flight neutron powder diffraction data have been collected from Na2MoO4 and Na2WO4 to a resolution of sin (theta)/lambda = 1.25 A(-1), which is substanti-ally better than the previous analyses using Mo Kalpha X-rays, providing roughly triple the number of measured reflections with respect to the previous studies [Okada et al. (1974 ). Acta Cryst. B30, 1872-1873; Bramnik & Ehrenberg (2004 ). Z. Anorg. Allg. Chem. 630, 1336-1341]. The unit-cell parameters are in excellent agreement with literature data [Swanson et al. (1962 ). NBS Monograph No. 25, sect. 1, pp. 46-47] and the structural parameters for the molybdate agree very well with those of Bramnik & Ehrenberg (2004 ). However, the tungstate structure refinement of Okada et al. (1974 ) stands apart as being conspicuously inaccurate, giving significantly longer W-O distances, 1.819 (8) A, and shorter Na-O distances, 2.378 (8) A, than are reported here or in other simple tungstates. As such, this work represents an order-of-magnitude improvement in precision for sodium molybdate and an equally substantial improvement in both accuracy and precision for sodium tungstate. Both compounds adopt the spinel structure type. The Na(+) ions have site symmetry .-3m and are in octa-hedral coordination while the transition metal atoms have site symmetry -43m and are in tetra-hedral coordination.

Fortes, A. D.,Crystal structures of spinel-type Na2MoO4 and Na2WO4 revisited using neutron powder diffraction, Acta Crystallogr E Crystallogr Commun, 2015, 71, 592.

Sodium molybdate - solubility

Determination and modelling for the solubility of Na2MoO4.2H2O in the (Na+ + MoO42- + SO42-) system

The solubility of Na2MoO4.2H2O in ( Na+ + MoO42- + SO42-) system was carried out using a dynamic method within the temperature range from 293.15 K to 343.15 K. The new model was established via regression of the published and the determined values to predict the solubility.

From the results, the solubility of sodium molybdate increases with the temperature increase, however, it decreases with the increasing concentration of sodium sulfate. The Pitzer parameters and the solubility product constant of sodium sulfate and sodium molybdate in aqueous solution were obtained using the literature data. The solubilities of the sodium molybdate in the sodium sulfate solution as well as the thermodynamic parameters were calculated based on the experimental values obtained. The new model was also applied to estimate the solubility of the sodium molybdate under various conditions. The calculated values agree well with the experiment results. (C) 2015 Published by Elsevier Ltd.

Ning, P. G., Xu, W. F., Cao, H. B., Lin, X., and Xu, H. B.,Determination and modeling for the solubility of Na2MoO4.2H2O in the (Na+ + MoO42- + SO42-) system, Journal of Chemical Thermodynamics, 2016, 94, 67-73.

MOLYBDENUM DISULFIDE MoS2

2D MoS2

Applications of Nanosheets in Frontier Cellular Research [REVIEW]

Several types of nanosheets, such as graphene oxide (GO) nanosheet, molybdenum disulfide (MoS2) and poly(l-lactic acid) (PLLA) nanosheets, have been developed and applied in vitro in cellular research over the past decade. Scientists have used nanosheet properties, such as ease of modification and flexibility, to develop new cell/protein sensing/imaging techniques and achieve regulation of specific cell functions. This review is divided into three main parts based on the application being examined: nanosheets as a substrate, nanosheets as a sensitive surface, and nanosheets in regenerative medicine. Furthermore, the applications of nanosheets are discussed, with two subsections in each section, based on their effects on cells and molecules. Finally, the application prospects of nanosheets in cellular research are summarized.

W. Huang, Y. Sunami, H. Kimura, and S. Zhang,Applications of Nanosheets in Frontier Cellular Research, Nanomaterials (Basel, Switzerland), 2018, 8.

2D MoS2

A comprehensive review on nano-molybdenum disulfide/DNA interfaces as emerging biosensing platforms

The development of nucleic acid-based portable platforms for the real-time analysis of diseases has attracted considerable scientific and commercial interest. Recently, 2D layered molybdenum sulfide (2D MoS2 from here on) nanosheets have shown great potential for the development of next-generation platforms for efficient signal transduction. Through combination with DNA as a biorecognition medium, MoS2 nanostructures have opened new opportunities to design and construct highly sensitive, specific, and commercially viable sensing devices. The use of specific short ssDNA sequences like aptamers has been proven to bind well with the unique transduction properties of 2D MoS2 nanosheets to realize aptasensing devices. Such sensors can be operated on the principles of fluorescence, electro-cheumuluminescence, and electrochemistry with many advantageous features (e.g., robust biointerfacing through various conjugation chemistries, facile sensor assembly, high stability with regard to temperature/pH, and high affinity to target). This review encompasses the state of the art information on various design tactics and working principles of MoS2/DNA sensor technology which is emerging as one of the most sought-after and valuable fields with the advent of nucleic acid inspired devices. To help achieve a new milestone in biosensing applications, great potential of this emerging technique is described further with regard to sensitivity, specificity, operational convenience, and versatility.

M. Kukkar, G. C. Mohanta, S. K. Tuteja, P. Kumar, A. S. Bhadwal, P. Samaddar, K. H. Kim, and A. Deep,A comprehensive review on nano-molybdenum disulfide/DNA interfaces as emerging biosensing platforms, Biosensors & bioelectronics, 2018, 107, 244-258.

 

Effects of dispersible MoS2 nanosheets and Nano-silver coexistence on the metabolome of yeast

As a new rising star in the post-graphene two-dimensional materials (2DMs), molybdenum disulfide (MoS2) attracts increasing attentions and is widely applied. However, the chemical and toxicological interaction between MoS2 and other co-contaminants is still poorly understood. Nano-silver (N-Ag) is the most commonly used nanomaterial in commercial products and distributed widely in the environment. Herein, we investigated the effects of chitosan functionalized MoS2 (CS-MoS2) nanosheets, a water-dispersible form of MoS2, on the microbial toxicity of N-Ag. We found that the incorporation of CS-MoS2 nanosheets attenuated the oxidative stress induced by N-Ag on yeast cells, while caused more membrane stress. In addition, the inhibition of N-Ag on the metabolic activities of yeast cells could be attenuated by CS-MoS2 nanosheets as well. The coexistence of N-Ag and CS-MoS2 nanosheets mainly perturbed the amino acid-related metabolic pathways in yeast cells, and phosphoric acid was a potential nanotoxicity biomarker. We further found that CS-MoS2 nanosheets dramatically absorbed the Ag ion released from N-Ag, which might be responsible for its attenuation effect on the microbial toxicity of N-Ag. Our findings provide more new insights for the ecotoxicity evaluation of MoS2 and other 2DMs.

Q. Yang, L. Zhang, A. Ben, N. Wu, Y. Yi, L. Jiang, H. Huang, and Y. Yu,Effects of dispersible MoS2 nanosheets and Nano-silver coexistence on the metabolome of yeast, Chemosphere, 2018, 198, 216-225.

Detection of chikungunya virus DNA using two-dimensional MoS2 nanosheets based disposable biosensor

Development of platforms for a reliable, rapid, sensitive and selective detection of chikungunya virus (CHIGV) is the need of the hour in developing countries. To the best of our knowledge, there are no reports available for the electrochemical detection of CHIGVDNA. Therefore, we aim at developing a biosensor based on molybdenum disulphide nanosheets (MoS2 NSs) for the point-of-care diagnosis of CHIGV. Briefly, MoS2 NSs were synthesized by chemical route and characterized using scanning electron microscopy, transmission electron microscopy, UV-Vis spectroscopy, Raman spectroscopy and X-Ray Diffraction. MoS2 NSs were then subjected to physical adsorption onto the screen printed gold electrodes (SPGEs) and then employed for the detection of CHIGV DNA using electrochemical voltammetric techniques. Herein, the role of MoS2 NSs is to provide biocompatibility to the biological recognition element on the surface of the screen printed electrodes. The detection strategy employed herein is the ability of methylene blue to interact differentially with the guanine bases of the single and double-stranded DNA which leads to change in the magnitude of the voltammetric signal. The proposed genosensor exhibited a wide linear range of 0.1 nM to 100 mu M towards the chikungunya virus DNA.

C. Singhal, M. Khanuja, N. Chaudhary, C. S. Pundir, and J. Narang,Detection of chikungunya virus DNA using two-dimensional MoS2 nanosheets based disposable biosensor, Scientific reports, 2018, 8.

MoS2 Nanoparticles as Electrocatalytic Labels in Magneto-Immunoassays

Ability to detect biomolecules with a simple and cost-effective approach has been very demanding in today's medicine. The nanoparticles and two-dimensional materials have been extensively used within this field in devices with high selectivity and sensitivity. Here, we report the use of MoS2 nanoparticles (MoS2 NPs) as a signal-enhancing label in a standard immunoassay test. MoS2 NPs were prepared by a bipolar electrochemistry method. The current response during the hydrogen evolution reaction catalyzed by MoS2 was measured. This current was directly proportional to the amount of the MoS2 NPs and thus also to the concentration of desired protein. The immunoassay containing the MoS2 NPs displays extraordinary low limit of detection (1.94 pg mL(-1)), good selectivity, and reproducibility. This MoS2 NP detection system could have profound implication for analytical applications.

D. Bousa, C. C. Mayorga-Martinez, V. Mazanek, Z. Sofer, K. Bousova, and M. Pumera,MoS2 Nanoparticles as Electrocatalytic Labels in Magneto-Immunoassays, ACS Appl Mater Interfaces, 2018, 10, 16861-16866.

               

2D MoS2 Nanostructures for Biomedical Applications

MoS2 nanosheets, a typical kind of layered transition metal dichalcogenides with the 2D structure and many unique physical and chemical properties, have attracted a lot of research interests in various fields. Typically, MoS2 nanosheets present similarities to graphene in terms of their large surface area and strong absorbance in near-infrared region, which in combination with their easily functionalized surface make them promising nanoplatforms in biomedical applications. Herein, the progress of MoS2 nanosheets and their composites in the area of nanomedicine, with the emphasis on their synthesis and modification strategies, their biomedical applications in biosensing, imaging and therapy, as well as evaluations of their in vivo behaviors and toxicology profiles are summarized. Finally, the challenges and opportunities of applying MoS2-based nanomaterials in the biomedicine areas will be discussed.

T. Liu, and Z. Liu,2D MoS2 Nanostructures for Biomedical Applications, Advanced Healthcare Materials, 2018, 7.

 

 

A comprehensive review on nano-molybdenum disulfide/DNA interfaces as emerging biosensing platforms

The development of nucleic acid-based portable platforms for the real-time analysis of diseases has attracted considerable scientific and commercial interest. Recently, 2D layered molybdenumsulfide (2D MoS2 from here on) nanosheets have shown great potential for the development of next-generation platforms for efficient signal transduction. Through combination with DNA as a biorecognition medium, MoS2 nanostructures have opened new opportunities to design and construct highly sensitive, specific, and commercially viable sensing devices. The use of specific short ssDNA sequences like aptamers has been proven to bind well with the unique transduction properties of 2D MoS2 nanosheets to realize aptasensing devices. Such sensors can be operated on the principles of fluorescence, electro-cheumuluminescence, and electrochemistry with many advantageous features (e.g., robust biointerfacing through various conjugation chemistries, facile sensor assembly, high stability with regard to temperature/pH, and high affinity to target). This review encompasses the state of the art information on various design tactics and working principles of MoS2/DNA sensor technology which is emerging as one of the most sought-after and valuable fields with the advent of nucleic acid inspired devices. To help achieve a new milestone in biosensing applications, great potential of this emerging technique is described further with regard to sensitivity, specificity, operational convenience, and versatility.

M. Kukkar, G. C. Mohanta, S. K. Tuteja, P. Kumar, A. S. Bhadwal, P. Samaddar, K. H. Kim, and A. Deep,A comprehensive review on nano-molybdenum disulfide/DNA interfaces as emerging biosensing platforms, Biosensors & bioelectronics, 2018, 107, 244-258.

 

An ultrasensitive detection of miRNA-155 in breast cancer via direct hybridization assay using two-dimensional molybdenumdisulfide field-effect transistor biosensor

MicroRNAs (miRNAs), critical biomarkers of acute and chronic diseases, play key regulatory roles in many biological processes. As a result, robust assay platforms to enable an accurate and efficient detection of low-level miRNAs in complex biological samples are of great significance. In this work, a label-free and direct hybridization assay using molybdenum disulfide (MoS2) field-effect transistor (FET) biosensor has been developed for ultrasensitive detection of miRNA-155 as a breast cancer biomarker in human serum and cell-line samples. MoS2, the novel 2D layered material with excellent physical and chemical properties, was prepared through sequential solvent exchange method and was used as an active channel material. MoS2 was comprehensively characterized by spectroscopic and microscopic methods and it was applied for fabrication of FET device by drop-casting MoS2 flacks suspension onto the FET surface. MoS2 FET device showed a relatively low subthreshold swing of 48.10mV/decade and a high mobility of 1.98 x 10(3)cm(2)V(-1)s(-1). Subsequently, probe miRNA-155 strands were immobilized on the surface of the MoS2 FET device. Under optimized conditions detection limit of 0.03fM and concentration range 0.1fM to 10nM were achieved. The developed biosensor not only was capable to identification of fully matched versus one-base mismatch miRNA-155 sequence, but also it could detect target miRNA-155 in spiked real human serum and extracts from human breast cancer cell-line samples. This approach paves a way for label-free, early detection of miRNA as a biomarker in cancer diagnostics with very high sensitivity and good specificity, thus offering a significant potential for clinical application.

S. M. Majd, A. Salimi, and F. Ghasemi,An ultrasensitive detection of miRNA-155 in breast cancer via direct hybridization assay using two-dimensional molybdenumdisulfide field-effect transistor biosensor, Biosensors & bioelectronics, 2018, 105, 6-13.

 

Peroxidase-like activity of MoS2 nanoflakes with different modifications and their application for H2O2 and glucose detection

MoS2 nanoflakes (MoS2 NFs) with a diameter of B390 nm were obtained by a facile one-pot hydrothermal method and the NFs exhibited intrinsic peroxidase-like activity. After being modified by commonly used biocompatible surfactants including polyethyleneimine (PEI), polyacrylic acid (PAA), polyvinylpyrrolidone (PVP), and cysteine (Cys), the peroxidase-like catalytic activities of MoS2 NFs were investigated by using 3,30,5,50-tetramethylbenzidine (TMB) and 2,20-azino-bis(3-ethylbenzothiazoline-6sulfonic acid) diammonium salt (ABTS) as chromogenic substrates. Compared to the polymer modified MoS2 NFs, Cys functionalized MoS2 NFs exhibited a high catalytic activity toward H2O2 in the presence of TMB or ABTS. Zeta potential and Michaelis-Menten analyses implied that the electrostatic force induced affinity or repulsion between the MoS2 NFs and substrates, as well as surface modifications of the MoS2 NFs played a key role in the catalytic reactions. Notably, a new peroxidase-like catalytic reaction mechanism was proposed based on the formation of a transient state of Cys-MoS2 NFs containing H2O2 and ABTS, and the catalytic reaction could occur because the Cys on the surface of the MoS2 NFs served as an electron transfer bridge between H2O2 and ABTS. Based on this finding, we also established a platform for colorimetric detection of H2O2 and glucose using Cys-MoS2 NFs as a peroxidase substitution. The limit of detection (LOD) was determined to be 4.103 mmol L-1 for H2O2, and the linear range (LR) was from 0 to 0.3 mmol L-1. The LOD for glucose was 33.51 mmol L-1 and the LR was from 0.05 to 1 mmol L-1, which is suitable for biomedical diagnosis. This work provides a new insight into the catalytic mechanism of peroxidase-like MoS2 NFs, and paves the way for enzyme-like nanomaterials to be used for medical diagnosis.

J. Yu, D. Q. Ma, L. Q. Mei, Q. Gao, W. Y. Yin, X. Zhang, L. Yan, Z. J. Gu, X. Y. Ma, and Y. L. Zhao,Peroxidase-like activity of MoS2 nanoflakes with different modifications and their application for H2O2 and glucose detection, Journal of Materials Chemistry B, 2018, 6, 487-498.

 

Enhancing the colloidal stability and surface functionality of molybdenum disulfide (MoS2) nanosheets with hyperbranched polyglycerol for photothermal therapy

Molybdenum disulfide (MoS2) nanosheets are gaining increasing attention due to their attractive properties and myriads of potential applications. However, challenges in the enhancement of their colloidal stability and surface functionality still remain and significantly restrict their practical applications. Herein, we present a viable approach to functionalize MoS2 nanosheets with multihydroxy hyperbranched polyglycerol (HPG) shell by surface-initiated ring-opening polymerization technique. The grafting of HPG from the surface of MoS2 nanosheet yielded MoS2-g-HPG nanohybrid with excellent water dispersibility, good biocompatibility, and greatly enhanced colloidal stability against pH change, ionic strength variation and long-term storage. The MoS2-g-HPG also exhibited excellent light-to-heat conversion capability for in vitro photothermal therapy application. Meanwhile, the MoS2-g-HPG showed favorable surface functionality owing to its numerous surface hydroxyl groups, as demonstrated by the conjugation of functional molecules such as fluorescent dye rhodamine B. As such, this paper opens up new opportunities to empower MoS2 nanosheets and other two-dimensional inorganic nanosheets with desired properties for various applications.

B. Huang, D. Wang, G. Wang, F. Zhang, and L. Zhou,Enhancing the colloidal stability and surface functionality of molybdenum disulfide (MoS2) nanosheets with hyperbranched polyglycerol for photothermal therapy, Journal of colloid and interface science, 2017, 508, 214-221.

 

Two-dimensional transition metal dichalcogenide nanomaterials for biosensing applications

Biosensors are powerful tools used to monitor biological and biochemical processes, ranging from clinical diagnosis to disease therapy. The huge demands for bioassays greatly promote the development of new nanomaterials as sensing platforms. Two-dimensional (2D) nanomaterials with superior properties, such as large surface areas and excellent conductivities, are excellent candidates for biosensor applications. Among them, single-or few-layered transition metal dichalcogenide (TMD) nanomaterials represent an emerging class of 2D nanomaterials with unique physical, chemical, and electronic properties. In this mini-review, we summarize the recent progress in 2D TMD nanomaterial-based biosensors for the sensitive detection of various kinds of targets, including nucleic acid, proteins, and small biomolecules, based on different sensors like optical sensors and electrochemical sensors, and bioelectronic sensors. Finally, the challenges and opportunities in this promising field are also proposed.

Y. L. Hu, Y. Huang, C. L. Tan, X. Zhang, Q. P. Lu, M. Sindoro, X. Huang, W. Huang, L. H. Wang, and H. Zhang,Two-dimensional transition metal dichalcogenide nanomaterials for biosensing applications, Materials Chemistry Frontiers, 2017, 1, 24-36.

 

Recent Advances in Synthesis and Biomedical Applications of Two-Dimensional Transition Metal Dichalcogenide Nanosheets

During recent decades, a giant leap in the development of nanotechnology has been witnessed. Numerous nanomaterials with different dimensions and unprecedented features have been developed and provided unimaginably wide scope to solve the challenging problems in biomedicine, such as cancer diagnosis and therapy. Recently, two-dimensional (2D) transition metal dichalcogenide (TMDC) nanosheets (NSs), including MoS2, WS2, and etc., have emerged as novel inorganic graphene analogues and attracted tremendous attention due to their unique structures and distinctive properties, and opened up great opportunities for biomedical applications, including ultrasensitive biosensing, biological imaging, drug delivery, cancer therapy, and antibacterial treatment. A comprehensive overview of different synthetic methods of ultrathin 2D TMDC NSs and their state-of-the-art biomedical applications, especially those that have appeared in the past few years, is presented. At the end of this review, the future opportunities and challenges for 2D TMDC NSs in biomedicine are also discussed.

X. Li, J. Y. Shan, W. Z. Zhang, S. Su, L. H. Yuwen, and L. H. Wang,Recent Advances in Synthesis and Biomedical Applications of Two-Dimensional Transition Metal Dichalcogenide Nanosheets, Small (Weinheim an der Bergstrasse, Germany), 2017, 13.

 

An Efficient and Benign Antimicrobial Depot Based on Silver-Infused MoS2

Silver nanoparticles (AgNPs) have been used as a broad-spectrum antimicrobial agent, whose toxicity originates from the localized release of Ag+ ions. However, the residual AgNPs core could generate potential risk to humans and waste of noble metals. Herein, we infused the cysteine-modified molybdenum disulfide with minimum Ag+ ions and coated with a layer of cationic polyelectrolyte to construct an efficient and benign antimicrobial depot. The system exhibited much enhanced broad-spectrum antibacterial activity compared with an equivalent amount of silver nitrate, owing to its increasing accessibility of released Ag+ to the cell walls of microorganisms. More importantly, the antibacterial system could be successfully applied to treat wound infection, while retaining high antibacterial activities, exhibiting negligible biotoxicity and avoiding the waste of Ag.


Cao, F. F., Ju, E. G., Zhang, Y., Wang, Z. Z., Liu, C. Q., Huang, Y. Y., Dong, K., Ren, J. S., and Qu, X. G.,An Efficient and Benign Antimicrobial Depot Based on Silver-Infused MoS2, Acs Nano, 2017, 11, 4651-4659.

Recent Advances in Synthesis and Biomedical Applications of Two-Dimensional Transition Metal Dichalcogenide Nanosheets
During recent decades, a giant leap in the development of nanotechnology has been witnessed. Numerous nanomaterials with different dimensions and unprecedented features have been developed and provided unimaginably wide scope to solve the challenging problems in biomedicine, such as cancer diagnosis and therapy. Recently, two-dimensional (2D) transition metal dichalcogenide (TMDC) nanosheets (NSs), including MoS2, WS2, and etc., have emerged as novel inorganic graphene analogues and attracted tremendous attention due to their unique structures and distinctive properties, and opened up great opportunities for biomedical applications, including ultrasensitive biosensing, biological imaging, drug delivery, cancer therapy, and antibacterial treatment. A comprehensive overview of different synthetic methods of ultrathin 2D TMDC NSs and their state-of-the-art biomedical applications, especially those that have appeared in the past few years, is presented. At the end of this review, the future opportunities and challenges for 2D TMDC NSs in biomedicine are also discussed.


Li, X., Shan, J. Y., Zhang, W. Z., Su, S., Yuwen, L. H., and Wang, L. H.,Recent Advances in Synthesis and Biomedical Applications of Two-Dimensional Transition Metal Dichalcogenide Nanosheets, Small, 2017, 13.

 

Molybdenum disulfide Biosensor

Dual-mode electrochemical analysis of microRNA-21 using gold nanoparticle-decorated MoS2 nanosheet

The detection of microRNA plays an important role in early cancer diagnosis. Herein, a dual-mode electronic biosensor was developed for microRNA-21 (miRNA-21) detection based on gold nanoparticle-decorated MoS2 nanosheet (AuNPs@MoS2). A classical DNA "sandwich" structure was employed to construct MoS2-based electrochemical sensor, including capture DNA, target miRNA-21 and DNA-modified nanoprobe. [Fe(CN)6]3-/4- and [Ru(NH3)6]3+ were selected as electrochemical indicators to monitor the preparation process and evaluate the performance of MoS2-based electrochemical biosensor by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV), respectively. Such MoS2-based biosensor exhibited excellent performance for miRNA-21 detection in the range from 10 fM to 1nM with detection limit of 0.78fM and 0.45fM for DPV and EIS technique, respectively. Furthermore, the proposed MoS2-based biosensor displayed high selectivity and stability, which could be used to determine miRNA-21 in human serum samples with satisfactory results. All data suggested that such MoS2-based nanocomposite may be a potential candidate for biosensing ranging from nucleic acid to protein detection.

Su, S., Cao, W., Liu, W., Lu, Z., Zhu, D., Chao, J., Weng, L., Wang, L., Fan, C., and Wang, L.,Dual-mode electrochemical analysis of microRNA-21 using gold nanopart icle-decorated MoS2 nanosheet, Biosensors & bioelectronics, 2017, 94, 552-559.

 

Molybdenum Sulfide: A Bioinspired Electrocatalyst for Dissimilatory Ammonia Synthesis with Geoelectrical Current

Abiotic reduction of nitrate/nitrite to ammonia in ancient ocean environments is essential for prebiotic chemical evolution and the early evolution of cellular metabolisms. Although Fe-bearing minerals have been extensively studied as reductants, the incompatibility of these reactions with the paleo-oceanic chemical conditions would have contributed only to low conversion rates. A recent model of prebiotic synthesis driven by geoelectricity suggests that less-abundant transition metals might have played a role in ammonia synthesis. Herein, we report that the electrochemical reduction of nitrate/nitrite to ammonia is effectively catalyzed by molybdenum sulfide over a wide pH range (pH 3-11). The pH dependence of the onset potential of the denitrification current indicates that this superior activity is due to the ability to induce concerted proton electron transfer (CPET), contributing to a turnover frequency comparable to those of the extant Mo dependent nitrate reductases. In a manner similar to biological dissimilatory denitrification, molybdenum sulfide catalyzes nitrite reduction to ammonia through NO and N2O intermediates, as revealed by online differential electrochemical mass spectroscopy. These findings demonstrate that molybdenum sulfide functions as a new family of bioinspired electrochemical denitrification catalysts and suggest that molybdenum, the indispensable element in extant denitrification enzymes, likely played an essential role in prebiotic ammonia synthesis with the continuous supply of geoelectrical current.

Li, Y., Yamaguchi, A., Yamamoto, M., Taka, K., and Nakamura, R.,Molybdenum Sulfide: A Bioinspired Electrocatalyst for Dissimilatory Ammonia Synthesis with Geoelectrical Current, Journal of Physical Chemistry C, 2017, 121, 2154-2164.

Structural influence of proteins upon adsorption to MoS2 nanomaterials: comparison of MoS2 force field parameters

Molybdenum disulfide (MoS2) has recently emerged as a promising nanomaterial in a wide range of applications due to its unique and impressive properties. For example, MoS2 has gained attention in the biomedical field because of its ability to act as an antibacterial and anticancer agent. However, the potential influence of this exciting nanomaterial on bioMolecules is yet to be extensively studied. Molecular dynamics (MD) simulations are invaluable tools in the examination of protein interactions with nanomaterials such as MoS2. Previous protein MD studies have employed MoS2 force field parameters which were developed to accurately Model bulk crystal structures and thermal heat transport but may not necessarily be amendable to its properties at the interface with bioMolecules. By adopting a newly developed MoS2 force field, which was designed to better capture its interaction with water and proteins, we have examined the changes in protein structures between the original and refitted MoS2 force field parameters of three representative proteins, polyalanine (alpha-helix), YAP65 WW-domains (beta-sheet), and HP35 (globular protein) when adsorbed onto MoS2 nanomaterials. We find that the original force field, with much larger van der Waals (vdW) contributions, resulted in More dramatic protein structural damage than the refitted parameters. Importantly, some denaturation of the protein tertiary structure and the local secondary structure persisted with the refitted force field albeit overall less severe MoS2 denaturation capacity was found. This work suggests that the denaturation ability of MoS2 to the protein structure is not as dire as previously reported and provides noteworthy findings on the dynamic interactions of proteins with this emergent material.

Gu, Z., De Luna, P., Yang, Z., and Zhou, R.,Structural influence of proteins upon adsorption to MoS2 nanomaterials: comparison of MoS2 force field parameters, Physical Chemistry Chemical Physics, 2017, 19, 3039-3045.

Two-dimensional MoS2: A promising building block for biosensors

Recently, two-dimensional (2D) layered nanomaterials have trigged intensive interest due to the intriguing physicochemical properties that stem from a quantum size effect connected with their ultra-thin structure. In particular, 2D molybdenum disulfide (MoS2), as an emerging class of stable inorganic graphene analogs with intrinsic finite bandgap, would possibly complement or even surpass graphene in electronics and optoelectronics fields. In this review, we first discuss the historical development of ultrathin 2D nanomaterials. Then, we are concerned with 2D MoS2 including its structure-property relationships, synthesis methods, characterization for the layer thickness, and biosensor applications over the past five years. Thereinto, we are highlighting recent advances in 2D MoS2-based biosensors, especially emphasize the preparation of sensing elements, roles of 2D MoS2, and assay strategies. Finally, on the basis of the current achievements on 2D MoS2 and other ultrathin layered nanomaterials, perspectives on the challenges and opportunities for the exploration of 2D MoS2-based biosensors are put forward.

Gan, X., Zhao, H., and Quan, X.,Two-dimensional MoS2: A promising building block for biosensors, Biosensors & bioelectronics, 2017, 89, 56-71.

MoS2 nanoparticle

Electrochemical H2O2 biosensor composed of myoglobin on MoS2 nanoparticle-graphene oxide hybrid structure

In this research, the electrochemical biosensor composed of myoglobin (Mb) on molybdenum disulfide nanoparticles (MoS2 NP) encapsulated with graphene oxide (GO) was fabricated for the detection of hydrogen peroxide (H2O2). Hybrid structure composed of MoS2 NP and GO (GO@MoS2) was fabricated for the first time to enhance the electrochemical signal of the biosensor. As a sensing material, Mb was introduced to fabricate the biosensor for H2O2 detection. Formation and immobilization of GO@MoS2 was confirmed by transmission electron microscopy, ultraviolet-visible spectroscopy, scanning electron microscopy, and scanning tunneling microscopy. Immobilization of Mb, and electrochemical property of biosensor were investigated by cyclic voltammetry and amperometric i-t measurements. Fabricated biosensor showed the electrochemical signal enhanced redox current as -1.86muA at an oxidation potential and 1.95muA at a reduction potential that were enhanced relative to those of electrode prepared without GO@MoS2. Also, this biosensor showed the reproducibility of electrochemical signal, and retained the property until 9 days from fabrication. Upon addition of H2O2, the biosensor showed enhanced amperometric response current with selectivity relative to that of the biosensor prepared without GO@MoS2. This novel hybrid material-based biosensor can suggest a milestone in the development of a highly sensitive detecting platform for biosensor fabrication with highly sensitive detection of target molecules other than H2O2.

Yoon, J., Lee, T., Bapurao, G. B., Jo, J., Oh, B. K., and Choi, J. W.,Electrochemical H2O2 biosensor composed of myoglobin on MoS2 nanoparticle-graphene oxide hybrid structure, Biosensors & bioelectronics, 2016.

ANTIBACTERIAL

2D molybdenum disulfide graphene oxide

Antibacterial Activities of Graphene Oxide-Molybdenum Disulfide Nanocomposite Films

Two-dimensional (2D) nanomaterials, such as graphene-based materials and transition metal dichalcogenide (TMD) nanosheets, are promising materials for biomedical applications owing to their remarkable cytocompatibility and physicochemical properties.

On the basis of their potent antibacterial properties, 2D materials have potential as antibacterial films, wherein the 2D nanosheets are immobilized on the surface and the bacteria may contact with the basal planes of 2D nanosheets dominantly rather than contact with the sharp edges of nanosheets.

To address these points, in this study, we prepared an effective antibacterial surface consisting of representative 2D materials, i.e., graphene oxide (GO) and molybdenum disulfide (MoS2), formed into nanosheets on a transparent substrate for real device applications.

The antimicrobial properties of the GO-MoS2 nanocomposite surface toward the Gram-negative bacteria Escherichia coli were investigated, and the GO-MoS2 nanocomposite exhibited enhanced antimicrobial effects with increased glutathione oxidation capacity and partial conductivity.

Furthermore, direct imaging of continuous morphological destruction in the individual bacterial cells having contacts with the GO-MoS2 nanocomposite surface was characterized by holotomographic (HT) microscopy, which could be used to detect the refractive index (RI) distribution of each voxel in bacterial cell and reconstruct the three-dimensional (3D) mapping images of bacteria. In this regard, the decreases in both the volume (67.2%) and the dry mass (78.8%) of bacterial cells that came in contact with the surface for 80 min were quantitatively measured, and releasing of intracellular components mediated by membrane and oxidative stress was observed.

Our findings provided new insights into the antibacterial properties of 2D nanocomposite film with label-free tracing of bacterial cell which improve our understanding of antimicrobial activities and opened a window for the 2D nanocomposite as a practical antibacterial film in biomedical applications.

Kim, T. I., Kwon, B., Yoon, J., Park, I. J., Bang, G. S., Park, Y., Seo, Y. S., and Choi, S. Y.,Antibacterial Activities of Graphene Oxide-Molybdenum Disulfide Nanocomposite Films, ACS Appl Mater Interfaces, 2017.

Antibacterial

Versatile molybdenum disulfide based antibacterial composites for in vitro enhanced sterilization and in vivo focal infection therapy

Biologically, MoS2-based nanostructures have been intensely applied for the photothermal therapy of cancer, but rarely for antibacterial uses. In this contribution, a multifunctional chitosan (CS) functionalized magnetic MoS2 (abbreviated to CFM) was constructed to nonspecifically combat bacterial infection by integrating bacterial conjugation and enrichment, and NIR-triggered photothermal sterilization. Owing to the abundant introduced amino groups, the CFM complex offers a significantly enhanced conjugation efficiency without obvious specificity towards both Gram-positive and -negative bacteria compared to amino-free magnetic MoS2. The magnetic properties of CFM obtained from iron oxide facilitate the enrichment of a CFM-bacteria conjugate, improving the photothermal efficiency of CFM as a photothermal antibacterial agent. Specifically, after being trapped together with bacteria cells, CFM shows an enhanced in vitro photothermal sterilization ability. In vivo S. aureus-induced abscess treatment studies show faster healing when CFM is used as subcutaneous nano-localized heating sources with the assistance of an external magnet to concentrate the CFM-bacteria conjugate. This work establishes an innovative solution and a novel antimicrobial agent for combating bacterial infections without the use of antibiotics, which may open a new area of application and research for MoS2-based nanostructures.

Zhang, W., Shi, S., Wang, Y., Yu, S., Zhu, W., Zhang, X., Zhang, D., Yang, B., Wang, X., and Wang, J.,Versatile molybdenum disulfide based antibacterial composites for in vitro enhanced sterilization and in vivo focal infection therapy, Nanoscale, 2016, 8, 11642-8.

MoS2 ANTIBACTERIAL

Functionalized Nano-MoS2 with Peroxidase Catalytic and Near-Infrared Photothermal Activities for Safe and Synergetic Wound Antibacterial Applications

We have developed a biocompatible antibacterial system based on polyethylene glycol functionalized molybdenum disulfide nanoflowers (PEG-MoS2 NFs). The PEG-MoS2 NFs have high near-infrared (NIR) absorption and peroxidase-like activity, which can efficiently catalyze decomposition of low concentration of H2O2 to generate hydroxyl radicals (.OH). The conversion of H2O2 into .OH can avoid the toxicity of high concentration of H2O2 and the .OH has higher antibacterial activity, making resistant bacteria more vulnerable and wounds more easily cured.

The PEG-MoS2 NFs combine the catalysis with NIR photothermal effect, providing a rapid and effective killing outcome in vitro for Gram-negative ampicillin resistant Escherichia coli (Ampr E. coli) and Gram-positive endospore-forming Bacillus subtilis (B. subtilis) as compared to catalytic treatment or photothermal therapy (PTT) alone.

Wound healing results indicate that the synergy antibacterial system could be conveniently used for wound disinfection in vivo.

Interestingly, glutathione (GSH) oxidation can be accelerated due to the 808 nm irradiation induced hyperthermia at the presence of PEG-MoS2 NFs proved by X-ray near-edge absorption spectra and X-ray spectroscopy.

The accelerated GSH oxidation can result in bacterial death more easily. A mechanism based on .OH-enhanced PTT is proposed to explain the antibacterial process.

Yin, W., Yu, J., Lv, F., Yan, L., Zheng, L. R., Gu, Z., and Zhao, Y.,Functionalized Nano-MoS2 with Peroxidase Catalytic and Near-Infrared Photothermal Activities for Safe and Synergetic Wound Antibacterial Applications, ACS nano, 2016, 10, 11000-11011.

Users of the Database should be aware that inclusion of an abstract in the Database does not imply any IMOA endorsement of the accuracy or reliability of the reported data or the quality of a publication.