Photocatalytic Coatings for Medical Applications
Decontamination of medical devices is an important and exciting area of research. Conventional decontamination strategies may not be wholly effective against some disease causing agents e.g. prion protein, responsible for CJD. Photocatalysis involves the use of light and a catalyst to generate reactive oxygen species which can degrade most organic materials. Therefore there is an opportunity to apply photocatalytic coatings to medical devices so that decontamination may be enhanced by light excitation. The most widely used photocatalyst is titanium dioxide (TiO2). It is chemically stable, photo-stable, photo-active, and non-toxic. TiO2 is a metal oxide semiconductor and irradiation with near UV light (< 400 nm) results in charge separation within the crystal i.e. the formation of electron-hole pairs. These charge carriers may migrate to the surface where they can react with adsorbed material. There are more than 5000 papers in the literature reporting the use of photocatalysis for the removal of both organic and inorganic pollutants from water and air (Mills and LeHunte 1997). Furthermore, photocatalysis has been reported to be effective for the killing of microorganisms (bacteria, fungi, and viruses) and cancer tumour cells (Blake, Maness et al. 1999). More recently there has been a move toward the use of photocatalytic ‘self-cleaning’ and ‘self-decontaminating’ surfaces eg Pilkington ActivTM self-cleaning glass. The use of TiO2 thin films for the photocatalytic decontamination of E. coli with the simultaneous degradation of endotoxin has also been reported (Fujishima, Rao et al. 2000) and other workers have reported the photocatalytic degradation of amino acids (Hidaka, Shimura et al. 1997) and proteins (Muszkat, Feigelson et al. 2001).
This research will involve the use of both physical and chemical methods of depositing thin films of photoactive titanium dioxide onto the surface of substrates e.g. stainless steel and polymers. These films will be characterised with respect to their physical and chemical properties using state of the art equipment available within the Nanotechnology Research Institute. The films will also be extensively tested for their photocatalytic properties and ability to degrade model organic and biological challenges.
References:
Blake, D. M., P. C. Maness, et al. (1999). "Application of the photocatalytic chemistry of titanium dioxide to disinfection and the killing of cancer cells." Separation and Purification Methods 28(1): 1-50.
Fujishima, A., T. N. Rao, et al. (2000). "TiO2 photocatalysts and diamond electrodes." Electrochimica Acta 45(28): 4683-4690.
Hidaka, H., T. Shimura, et al. (1997). "Photoelectrochemical decomposition of amino acids on a TiO2/OTE particulate film electrode." Journal of Photochemistry and Photobiology a-Chemistry 109(2): 165-170.
Mills, A. and S. LeHunte (1997). "An overview of semiconductor photocatalysis." Journal of Photochemistry and Photobiology a-Chemistry 108(1): 1-35.
Muszkat, L., L. Feigelson, et al. (2001). "Titanium dioxide photocatalyzed oxidation of proteins in biocontaminated waters." Journal of Photochemistry and Photobiology B-Biology 60(1): 32-36.
Personnel Involved
First Supervisor: Byrne, J Dr
Second Supervisor: Burke, G Dr
Collaboration: This project does not involve collaboration with another establishment
Synopsis:
Decontamination of medical devices is an important and exciting area of research. Conventional decontamination strategies may not be wholly effective against some disease causing agents e.g. prion protein, responsible for CJD. Photocatalysis involves the use of light and a catalyst to generate reactive oxygen species which can degrade most organic materials. Therefore there is an opportunity to apply photocatalytic coatings to medical devices so that decontamination may be enhanced by light excitation.