Bacteria are responsible for 2 million infections and 23,000 deaths in the U.S. every year, according to the U.S. Centers for Disease Control and Prevention. Bacterial resistance to antibiotics is also on the rise as a result of their excessive use throughout populations. Patients in hospitals who are already battling illnesses or have compromised immune systems are especially at risk of developing infections just by touching contaminated bedrails and door knobs.
In recent years, scientists across the globe have been working on developing coatings and materials that bacteria cannot grow on, to fight the spread and growth of microbes on these high-touch surfaces.
Researchers from University of Massachusetts’ Department of Polymer Science and Engineering have designed one such coating that is infused with antimicrobial agents and has the patterned diamond-like texture of shark skin. ‘Sharklet AF™’ is a coating designed to mimic a shark’s skin, and it reduces the ability of bacteria to adhere to surfaces.
The skin of sharks is comprised of nanoscale overlapping plates that exhibit parallel ridges. This unique formation creates an irregular surface, which is what effectively prevents sharks from becoming fouled (attachment of smaller organisms), even when moving at slow speeds. Products inspired by shark skin have previously been developed in the anti-fouling industry, to reduce the amount of barnacles and other marine life attaching to the hulls of ships.
The Sharklet AF™ coating works through combining antifouling shark-skin inspired patterns with titanium dioxide (TiO2) nanoparticles (which are antibacterial), and has shown to decrease microbial attachment and inactivate attached microorganisms. The shark-skin microstructures were imprinted on on a poly(ethylene terephthalate) (PET) substrate using solvent-assisted soft nanoimprint lithography.
The shark-skin-patterned surface reduced the attachment of Escherichia coli by ∼70% compared with smooth films with the same chemical composition. By incorporating as low as 10 wt % TiO2 nanoparticles into the chemical matrix, over 95% E. coli and up to 80% Staphylococcus aureus were inactivated within 1 h UV light exposure because of the photocatalytic properties of TiO2.
The researchers says the fabrication method could be scaled up for mass production and could well be an effective coating for use in hospitals and other environments where people are at high risk of bacterial infection.
Bioinspired Photocatalytic Shark-Skin Surfaces with Antibacterial and Antifouling Activity via Nanoimprint Lithography
Feyza Dundar Arisoy, Kristopher W. Kolewe, Benjamin Homyak, Irene S. Kurtz, Jessica D. Schiffman, and James J. Watkins
ACS Applied Materials & Interfaces 2018 10 (23), 20055-20063