Chemical Vapour Deposition for the Generation of Visible Light Activated Antimicrobial Coatings

The goal of this research is to prepare new antimicrobial coatings that will work under normal room lighting conditions. The new coatings will be able to use visible light to dsetroy and decontaminate the surface and will be able to do so for all bacteria and viruses. They will be particularly useful in a hospital environment where they will be of great benefit in reducing transmission of hospital acquired infections- in particular MRSA.The coatings work by absorbing visible light and converting this into active species called radicals that chew up and destroy the walls of a bacteria or virus and hence inactivate the organism. The key part of the new science here is that by modifying an existing material called titanium dioxide we will be able to ensure that it can capture visible light. Up to now the titanium dioxide coatings would only be effective in combination with ultra-violet light from lamp sources. These are dangerous (direct UV can cause eye damage), energy intensive and not pratical to use on a large scale.The new coatings will be produced by chemical vapour deposition. This is a method of laying down a coating from material in the gas phase. We have developed a new combinatorial approach which enables films of graded composition to be depositied. By measuring the properties of the film at each point we are very rapidly able to examine what is the best composition mix in the film to obtain maximum visible light havesting.The efficacy of the new coatings at destroying organic chemicals, bacteri and a virus will be examined using normal room lighting.One further feature of the new coatings is that form very slippery surfaces. In fact water forms puddles and sheets on the surface rather than droplets or rivulets. This means that the coatings wash down uniformly any dirt or bacteria on their surfaces. One exciting aspect of the project is to measure how well bacteria will adhere to the surface and to measure the ease of biofilm formation. The biofilm stage is a critical one in assessing how well a film will form, adhere and colonise - contaminate a surface. We anticipate that these new coatinsg will prove exceptionally difficult for bacteria to colonise.