Biofilms are present all around us, from the green slime we see on rocks to the plaque on our teeth. Yet these glue-like communities of microorganisms are the root of growing numbers of hospital infections, and can cause serious corrosion problems in industry. Now US scientists have developed a way to control biofilm formation, making it easier to study biofilm growth - a key step in finding ways to prevent it. 

Biofilms grow only on selected areas of Luk and Ren's patterned gold surface

Using surface engineering Yan-Yeung Luk, Dacheng Ren and colleagues at Syracuse University can confine bacterial biofilm growth to specific patterns for long periods of time. 

'Compared to free swimming cells, attached biofilm cells are extremely difficult to eradicate because they can tolerate up to 1000 times higher doses of antibiotics and disinfectants,' explains Ren. 'To prevent biofilm formation and remove established biofilms effectively, it is critical we understand the mechanism of biofilm formation.' However, he points out, this has proved challenging due to a lack of suitable or reliable surfaces, with well-defined surface chemistry, to study their growth on. 

From past work Ren's team knew that biofilms grow readily on gold surfaces coated with a monolayer of a methyl-terminated thiol. However, by swapping the methyl group for the well-known artificial sweetner, D-mannitol, the researchers found they could also inhibit biofilm formation. They then created a surface where the biofilm-friendly thiols were surrounded by biofilm-unfriendly thiols. In this way they were able to make the biofilm grow vertically instead of spreading outwards, giving them control over the biofilm's 3D structure.

Previous surfaces developed to inhibit biofilms have shown poor resistance and longevity. The surface developed by Ren and co-workers inhibited biofilm growth for up to 26 days. 'To the best of our knowledge, there is no prior chemistry that can control patterned biofilm formation with this level of resistance,' said Ren.

Blake Peterson, a professor of medicinal chemistry at the University of Kansas, in Lawrence, US, sees great promise in the method. 'The surface's remarkable long-term biofilm resistance has the potential to lead to the development of improved medical implants such as stents, shunts, prostheses, and catheters that can be compromised by biofilm-associated infections,' he says.

Sarah Corcoran

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