Creating a “Liquid” Surface
In SLIPS materials, a very thin film of liquid is stably attached to a solid surface. In the present study, polytetrafluroethylene (PTFE) was used as the solid surface, which was infused with a highly repellant commercial fluid – Dupont TM Krytox ® 103 – to make the liquid thin film.
Dr. Tak Sing Wong, one of the leading researchers of this study, explained the principle and the novelty of the work to Decoded Science.
“The peculiarity of our system is that we do not have a ‘standard’ solid surface, but a liquid which is attached to the solid surface. The liquid consists of highly mobile molecules; therefore, it is difficult for the bacteria to establish ‘permanent’ interactions with them. The bacterial shear adhesion is extremely low, and this greatly inhibits the biofilm formation under mild flow/shear conditions.
“This is the opposite of what happens on conventional solid anti-biofouling materials, where the atoms/molecules are static and bacteria have a strong surface adhesion.”
This feature can be observed in the below video of SLIPS in action. You can see how a bacteria-containing solution is very mobile on a SLIPS surface, without showing any adhesion. On the unmodified PTFE surface, in comparison, the solution stays in place.
Biofilms Formation Prevention
Tests on the biofilm formation were performed for several species. The bacterial attachment was monitored for a 7-day period for Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. The biofilm attachment on SLIPS surfaces was reduced by 99.6, 97.2 and 96.0% respectively, in comparison with the attachment of the biofilm to the untreated PTFE.
According to Dr. Wong “this is approximately 35 times better than the results achieved by the current best available material (PEGylated surface), and over a far longer timeframe.”
This research, and the anti-biofilm surfaces in hospitals that will result, have the potential to save many lives by inhibiting the growth of bacteria, and reducing staph infections and the spread of disease.
Epstein, A. et al. Liquid-infused structured surfaces with exceptional anti-biofouling properties. (2012). Proceedings of the National Academy of Sciences USA, www.pnas.org/cgi/doi/10.1073/pnas.1201973109. Accessed on August 2, 2012.
Walker, E. Hospital Acquired Infection Costly, Preventable. MedPage Today. Accessed on August 2, 2012.
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