Innnovative functional coatings with transition metal oxides and their antimicrobial and catalytic properties

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Composites of transition metal oxides (MoO3 and WO3) represent a new class of important materials that are increasingly being developed for use in research due to their favourable physical and chemical properties. These materials are of particular interest as antimicrobial agents and as catalysts in numerous biological, chemical, biomedical and pharmaceutical applications. In the initial project period, we could distinctly demonstrate that compounds comprising transition metal oxides (e.g. MoO3) are highly efficient materials to permanently prevent colonisation of harmful microorganisms of inanimate surfaces. We reported on the reduction of microbial contamination and biofilm growth on inanimate surfaces with incorporated different crystal structures of MoO3 into the various polymer substrates. Many scientific issues related to the mechanism and the catalytic properties related to the antimicrobial activity arose, which will be addressed in the proposed project period. We could also show that MoO3-TiO2 composite with systematically varied compositions prepared by sol-gel-processing exhibit significant photocatalytic degradation properties. As a further development on the application of transition metal oxides we envision the exploration of the catalytic properties for the degradation of lignocellulosic materials. This will enable a cost efficient and green route to produce low-molecular weight compounds. The first aim of this continuation proposal is to elaborate on the antimicrobial mechanism of molybdenum oxide. We propose that the crystallographic phase and water content in MoO3 strongly influence on the antimicrobial activity. The phase and composition will be varied by adapting the materials processing parameters (e.g. thermal treatment). The antimicrobial properties of the synthesised composites will be evaluated as a function of the crystallographic phase. The second scientific issue is related to the charge density distribution on the modified surfaces which avoid the growth, spread and transfer of the microorganisms. Evaluation of the charge density as a function of the molybdenum oxide particle distribution in materials will be envisioned. Based upon the results on the antimicrobial properties and our observation on the photocatalytic properties, the transition metal oxides will be developed as catalytically active materials for photo and chemically induced degradation reactions. One major work hypothesis is that transition metal oxides and their composites are able to degrade lignocellulosic biopolymer compositions for producing low-molecular weight compounds in an ecological and cost efficient route. The influence of different composite materials of MoO3 on the yield of low-molecular weight compounds and residual biopolymers will be elucidated. We believe that this proposal has a substantial importance for future industrial applications in the area of biomass conversion and as antimicrobial agents.