Scientists manage to prevent biofilms forming on surfaces

Biofilms can stick to a myriad of surfaces and their presence can result in decreased energy efficiency, contamination of water and food supplies and persistent infections.

In a study published in the Proceedings of the National Academy of Sciences (PNAS), lead co-authors Joanna Aizenberg, Alexander Epstein and Tak-Sing Wong coated solid surfaces with an immobilised liquid film to trick the bacteria into thinking they had nowhere to attach and grow.

‘People have tried all sorts of things to deter biofilm build-up — textured surfaces, chemical coatings and antibiotics, for example,’ said Aizenberg, Amy Smith Berylson Professor of Materials Science at the Harvard School of Engineering and Applied Sciences (SEAS). ‘In all those cases, the solutions are short lived at best. The surface treatments wear off, become covered with dirt, or the bacteria even deposit their own coatings on top of the coating intended to prevent them. In the end, bacteria manage to settle and grow on just about any solid surface we can come up with.’

According to the university, the researchers used their recently developed technology, dubbed SLIPS (slippery-liquid-infused porous surfaces) to create a hybrid surface that is smooth and slippery due to the liquid layer that is immobilised on it.

First described in the 22 September 2011 issue of the journal Nature, the slippery surfaces have been shown to repel water- and oil-based liquids and prevent ice or frost from forming.

‘By creating a liquid-infused structured surface, we deprive bacteria of the static interface they need to get a grip and grow together into biofilms,’ said Epstein, a recent PhD graduate who worked in Aizenberg’s lab at the time of the study.

‘In essence, we turned a once bacteria-friendly solid surface into a liquid one. As a result, biofilms cannot cling to the material, and even if they do form they easily slip off under mild flow conditions,’ added Wong, a researcher at SEAS and a Croucher Foundation postdoctoral fellow at the Wyss Institute.

Aizenberg and her collaborators reported that over a seven-day period SLIPS reduced the formation of Pseudomonas aeruginosa, Escherichia.coli and Staphylococcus aureus by 96 per cent.

According to a statement, the technology works in a static environment and under flow, or natural conditions, making it suitable for coating implanted medical devices that interact with bodily fluids. The coated surfaces can also combat bacterial growth in environments with extreme pH levels, intense ultraviolet light and high salinity.

SLIPS is non-toxic, readily scalable and self cleaning, needing nothing more than gravity or a gentle flow of liquid to stay unsoiled.

The approach may find use in medical, industrial and consumer products and settings.