Biocidal silver and silver/titania composite films grown by chemical vapour deposition

This paper describes the growth and testing of highly active biocidal films based on photocatalytically active films of TiO2, grownby thermal CVD, functionally and structurallymodified by deposition of nanostructured silver via a novel flame assisted combination CVD process. The resulting composite films are shown to be highly durable, highly photocatalytically active and are also shown to possess strong antibacterial behaviour. The deposition control, arising from the described approach, offers the potential to control the film nanostructure, which is proposed to be crucial in determining the photo and bioactivity of the combined film structure, and the transparency of the composite films. Furthermore, we show that the resultant films are active to a range of organisms, including Gram-negative and Gram-positive bacteria, and viruses. The very high-biocidal activity is above that expected from the concentrations of silver present, and this is discussed in terms of nanostructure of the titania/silver surface. These properties are especially significant when combined with the well-known durability of CVD deposited thin films, offering new opportunities for enhanced application in areas where biocidal surface functionality is sought

Photocatalytic antimicrobial activity of thin surface films of TiO2, CuO and TiO2 /CuO dual layers on Escherichia coli and bacteriophage T4

TiO2 coated surfaces are increasingly studied for their ability to inactivate microorganisms. The activity of glass coated with thin films of TiO2, CuO and hybrid CuO/TiO2 prepared by atmospheric Chemical Vapour Deposition (Ap-CVD) and TiO2 prepared by a sol-gel process was investigated using the inactivation of bacteriophage T4 as a model for inactivation of viruses. The chemical oxidising activity was also determined by measuring stearic acid oxidation. The results showed that the rate of inactivation of bacteriophage T4 increased with increasing chemical oxidising activity with the maximum rate obtained on highly active sol-gel preparations. However these were delicate and easily damaged unlike the Ap-CVD coatings. Inactivation rates were highest on CuO and CuO/TiO2 which had the lowest chemical oxidising activities. The inactivation of T4 was higher than that of Escherichia coli on low activity surfaces. The combination of photocatalysis and toxicity of copper acted synergistically to inactivate bacteriophage T4 and retained some selfcleaning activity. The presence of phosphate ions slowed inactivation but NaCl had no effect. The results show that TiO2/CuO coated surfaces are highly antiviral and may have applications in the food and healthcare industries

The growth of copper oxides on glass by flame assisted chemical vapour deposition

Flame assisted chemical vapour deposition is a low cost, relatively simple atmospheric pressure chemical vapour deposition (CVD) technique that is compatible with both small volume, batch, and high volume continuous coating processes. Use of this method with low hazard aqueous solutions of simple metal salts can yield metal oxide thin films, which represents a major advantage in terms of precursor cost and environmental impact compared to alternative CVD methods. In this paper we report the extension of this technique to the growth of copper oxides from aqueous solutions of cupric nitrate (Cu(NO3)2) and discuss the effects on the films of the various growth conditions. It is shown that copper oxide films are produced with nanostructure controlled properties. Furthermore, we report that these films have strong antibacterial activity

Photo-induced self-cleaning and biocidal behaviour of titania and copper oxide multilayers

This paper describes the deposition of films of titania and copper oxide by atmospheric pressure chemical vapour deposition (CVD). The films were investigated as part of multilayer systems to assess their potential to offer the dual functionality of self-cleaning and biocidal films. The multilayer systems were achieved by deposition of copper oxide with subsequent titanium dioxide deposition and vice versa. Two different CVD approaches were employed in combination, thermal CVD and flame-assisted CVD. It is shown that by careful choice of the experimental growth conditions, multilayers can be formed with both biocidal and ‘self-clean’ functionality under UV photo-induced conditions