Innnovative functional coatings with transition metal oxides and their antimicrobial and catalytic properties
Solid State and Surface Chemistry, Material Synthesis
Final Report Abstract
Composites of transition metal oxides such as MoO3 and WO3 with ceramics, metals and polymers represent a new class of materials which were developed for the use as antimicrobial agents and as catalysts in various applications. Within the project, we could distinctly demonstrate that compounds comprising transition metal oxides (e.g. MoO3) are extraordinarily efficient materials to permanently prevent colonisation of harmful microorganisms such as Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa on inanimate surfaces (ceramics, metal, polymers). Many scientific issues related to the mechanism and the catalytic properties related to the antimicrobial activity arose, which were addressed during the project. We could also show that MoO3-TiO2 composites with systematically varied compositions prepared by sol-gel-processing exhibit significant photocatalytic degradation properties. A strong influence of the crystallographic phase and water content in MoO3 on the antimicrobial activity was elucidated. Our results show that the crystal structures of molybdenum oxides including hexagonal, monoclinic and orthorhombic polymorphs exhibit a good to excellent antimicrobial activity. To further improve the antimicrobial properties, molybdenum trioxide dihydrate (MoO3×2H2O) was prepared. Analysis of the thermal phase development and morphological evolution during and after calcination up to 600 °C showed that the dehydration of the material proceeds in two steps. Extraordinary antimicrobial activities were determined for anhydrous samples with an orthorhombic crystal structure and a large specific surface area. The increase in the specific surface area is due to crack formation and to the loss of the hydrate water after calcination at 300 °C. The results support the proposed antimicrobial mechanism for transition metal oxides, which is based on a local acidity increase as a consequence of the augmented specific surface area. A novel materials concept to prevent growth of harmful bacteria on biopolymer material surfaces which consists of embedded orthorhombic molybdenum trioxide particles was also developed. Plasticized biopolymer (cellulose acetate) surfaces with MoO3 were virtually free of bacteria within 6h after incubation with an infectious solution. As a further development on the application of transition metal oxides, we explored the catalytic properties for the degradation of lignocellulosic materials. This will enable a cost efficient and green route to produce industrial relevant low-molecular weight compounds. The results from mechanical tests demonstrated that adding the antimicrobial agents (MoO3) into the biopolymer substrates have no negative effect on the strength, elasticity and usability under impeding conditions. There is an extraordinary broad spectrum of antimicrobial activity using the developed technology on various surfaces endowed with transition metalloacids, including Gram-positive and Gram-negative microorganisms irrespective of their resistance against antibiotics, fungi, legionella and virus. The activity also includes the most multiresistant microorganisms causing nosocomial infections. The eradication of microorganisms is fast, meeting under certain circumstances even the criteria of disinfection. The investigated and developed antimicrobial materials and prepared composites with MoO3 and related compounds are alternative agents for conventional antibiotics to decrease the risk of health care associated infections, which is one of the most important causes of disease with lethal consequences at present. The developed technique can be applied for materials used in modern medicine and public environments.
Publications
- (2011) Anodic TiO2 nanotube layers electrochemically filled with MoO3 and their antimicrobial properties. Biointerphases 6, 16-21
Lorenz K, Bauer S, Gutbrod K, Guggenbichler JP, Schmuki P, Zollfrank C
(See online at https://dx.doi.org/10.1116/1.3566544) - (2012) The antimicrobial activity of transition metal acid MoO3 prevents microbial growth on material surfaces. Materials Science and Engineering C: Biomimetic and Supramolecular Systems, 32, 47-54
Zollfrank C, Gutbrod K, Wechsler P, Guggenbichler JP
(See online at https://doi.org/10.1016/j.msec.2011.09.010) - (2013) Polymorphs of molybdenum trioxide as innovative antimicrobial materials. Surface Innovations 1, 202-208
Shafaei S, Lackner M, Meier M, Plank, J, Guggenbichler JP, Zollfrank C
(See online at https://doi.org/10.1680/si.13.00021) - (2013) Synthesis of titanium(IV) oxide / molybdenum(VI) oxide based photocatalysts by a simple sol gel route. Journal of Sol-Gel Science and Technology, 66, 112-119
Gutbrod K, Zollfrank C
(See online at https://doi.org/10.1007/s10971-013-2973-1) - (2014) Innovative Development in Antimicrobial Materials. Recent Patents on Materials Science, 7, 26-36
Shafaei S, Lackner M, Voloshchuk R, Voloshchuk I, Guggenbichler JP, Zollfrank C
- (2016) Enhancement of the antimicrobial properties of orthorhombic molybdenum trioxide by fracturing hydrates. Materials Science and Engineering C 58, 1064–1070
Shafaei S, Van Opdenbosch D, Fey T, Koch M, Kraus T, Guggenbichler JP, Zollfrank C
(See online at https://doi.org/10.1016/j.msec.2015.09.069) - (2017) Cellulose acetate based composites with antimicrobial properties from embedded molybdenum trioxide particles. Letters of Applied Microbiology, 64, 43-50
Shafaei S, Dörrstein J, Guggenbichler JP, Zollfrank C
(See online at https://doi.org/10.1111/lam.12670)
