Coatings clear up

New coatings that are said to tackle metal corrosion and hospital-acquired infections were presented recently to the Society for General Microbiology in Harrogate.

The first makes use of a naturally occurring bacteria to deal with the corrosion of metals at sea. Developed by researchers at Sheffield Hallam University, the coating includes spores from a bacterium into a sol-gel coating that can then be used to protect aluminium alloys from microbial damage.

David Greenfield, a researcher on the project, explained: 'Some bacteria can lay down a biofilm over a surface and this can be detrimental to the metal underneath. We've tried to counteract this process by selecting specific spores from a bacterium.

'We also wanted to create a coating that could be cured at lower temperatures compared with inorganic sol-gel. We're still working on this. However, our current coating can be cured at far lower temperatures so as not to damage or modify the shape of the metal,' he added.

The corrosion of metals at sea is estimated to cost the UK a significant amount of money. Existing treatments to combat the problem are often expensive and can include biocides and inhibitors that are toxic to aquatic life. However, the team at Sheffield claims that the coating is environmentally friendly and can be cured at temperatures of up to 90°C.

Trials have so far shown that the bacteria-containing coating is substantially more effective in the prevention of corrosion than a sol-only coating. The team is currently investigating the causes behind corrosion protection, which it believes may be a result of the production of antimicrobial agents that inhibit the growth of damaging substances such as hydrogen sulphide.

Presenting their findings alongside Sheffield Hallam, researchers at UCL Eastman Dental Institute claim to have developed a 99.9 per cent-effective hard coating for killing Escherichia coli (E.Coli) bacteria when activated by white light.

Jonathan Pratten, who is working on the project, said: 'Our multi-disciplinary team of chemists and microbiologists is the first to develop a titanium-dioxide/nitrogen coating that kills bacteria under white light. In the future, if this can be translated into the clinic, it should help reduce the numbers of bacteria that are associated with hospital-acquired infections.'

Existing titanium-dioxide-based coatings can kill bacteria after activation with UV light. By introducing nitrogen into the chemical make-up, photons-visible light can be utilised and activated to kill bacteria.

Pratten added: 'There is nothing on the market at present that is activated by white light — the shortcoming may be when the lights are switched off, but we are looking into how long it will remain active in this scenario.

'This is a coating that could be applied to anything. The most obvious application is the hospital setting because of the light being used, but it could also have applications in the home and kitchen.'

Both projects are currently undergoing additional trials with plans to speak to industrial partners about further development.

Ellie Zolfagharifard