Guanidine: an antimicrobial surface coating not only for medical use

23 marzo 2017

A guanidine surface coating for PVC materials has already been proved to be an effective antimicrobial solution in biomedical devices, but its use could even go way beyond that, according to Enrique Rodríguez-Castellón, Professor of Inorganic Chemistry at the Universidad de Málaga and one of the participants in this new development.

A guanidine surface coating for PVC materials has already been proved to be an effective antimicrobial solution in biomedical devices, but its use could even go way beyond that, according to Enrique Rodríguez-Castellón, Professor of Inorganic Chemistry at the Universidad de Málaga and one of the participants in this new development.

A biomedical solution

PVC is one of the most used plastic materials in biomedical devices such as tubes, catheters, bottles, packaging, etc. The problem is that upon contact with biological fluids, PVC is prone to suffer microbial colonization and, therefore, it ends up causing infections, which is a serious problem in hospitals. This is why PVC modification is currently being studied, and guanidine might be a good solution.

Guanidine is an antibacterial coating that sticks on PVC and eliminates surface roughness. "This coating modifies the surface of the polymer and increases its hydrophobicity", Rodríguez-Castellón says. "Once bacteria set on the surface, guanidine is able to go through their membranes and, by osmotic pressure, break the cell walls and stop their development". Some additional antibiotic compounds could also be applied on guanidine to reinforce the effects.

The recent development of this coating has been led by the Univesidad de Buenos Aires, Argentina, and the Universidad de Málaga, Spain. The topic, however, is not new. One of the most effective antibacterial solutions so far has been the application of silver nanoparticles, "as in ‘Silestone', which was pointed out as one of the best technological innovations in the 20th centuy by Harvard University", Rodríguez-Castellón explains. "But silver is way too expensive to be used in non-reusable medical instrumentation".

New recycling opportunities

Most plastic biomedical devices and non-reusable, but guanidine might change that in some cases. "We have also analysed if we could reuse these materials and if they would keep the antimicrobial properties after sterilisation. And the answer is yes. PVCs modified with guanidine is resistant to washing and they keep the required elastic and plastic properties. Therefore, they could be reused", in Rodríguez-Castellón words.
The development is in its experimental phase yet, but the scientists are thinking of creating a start-up to take it to a larger scale. "We have to analyse the cost of applying four layers of coating, which is what is required, in a large scale and see", he says.

Further applications

Although the basic research on guanidine-modified PVCs has focused on biomedical devices, its application could go way beyond that use. Rodríguez-Castellón says that the same product could be applied "to walls and other surfaces not only in hospitals but also in all kind of facilities with lots of visitors, such as airports or train stations. The goal would be to develop some way to apply this antimicrobial coating, similar to painting, and avoid bacteria to live and grow on walls".

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