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Materials

25: Protective antibacterial films inspired by sharkskin

Problem:

Hospital-acquired or nosocomial infections are deadly, resulting in more than 99,000 deaths each year

Solution:

Medical protective films and supplies like wound dressings and catheters that inhibit bacterial growth by mimicking the texture of sharkskin.

Dr. Anthony B. Brennan, materials science and engineering professor at University of Florida, had been asked by the U.S. Office of Naval Research to identify new antifouling strategies to reduce use of toxic antifouling paints and trim costs associated with dry dock and drag.

Brennan was convinced that using an engineered topography could be a key to new antifouling technologies.

This became clear upon watching an algae-coated nuclear submarine return to port while visiting the U.S. naval base at Pearl Harbor in Oahu in 2002. The submarine was strikingly similar in appearance to a whale moving slowly into the harbour. This observation resulted in a discussion on the topic of slow moving marine mammals that do not readily collect microorganisms on their skin.

The only animal identified with that met these criteria was the shark. Following identification, Brennan became expert in understanding what properties of sharkskin contribute to the difference in adhesion.

An actual impression of sharkskin, or more specifically, its dermal denticles was taken in an effort to understand these properties. Examining the impression with scanning electron microscopy Brennan discovered that sharkskin denticles are arranged in a distinct diamond pattern with tiny riblets.

The presence of millions of tiny diamond-shaped dermal denticles is unique to sharks in comparison to other slow moving marine animals and is key to the micro-organism resistant properties of sharkskin. He called them Sharklets. The first test performed showed an 85% reduction in green algae settlement compared to smooth surfaces.

Taking a biomimicry approach Anthony Brennan has adapted the Sharklets to develop a textured adhesive film which can stop bacterial growth on a number of different surfaces, including medical devices such as hospital surfaces, public restrooms, childcare facilities, commercial venues, laboratories and animal research facilities. The film may also be manufactured into the top layer of workspace mats to create immediate and moveable surface protection.

For manufacturing, Brennan set up Sharklet™ Technologies Inc., a biotechnology company is based at the Bioscience Park Center, an incubator in the Fitzsimons Life Science District adjacent to the renowned Anschutz Medical Campus in Aurora, Colorado.

To test Sharklet, trials were conducted in Sharklet Inc. laboratories, independent facilities and United States’ government agency facilities, on bacteria incuding Staphylococcus aureus, Staphylococcus epidermidis, MRSA, Pseudomonas aeruginosa, Escherichia coli and VRE.

LG International in Portland, Oregon, a manufacturer of bacteria inhibition products, designed to protect environmental surfaces and decrease bacterial attachment, survival, and touch transference, was the first company to sell a bacteria-inhibiting film-based product under the Tactivex brand.

Tactivex has been deployed into healthcare facilities, research laboratories and other settings where bacterial inhibition is desired. Tactivex with Sharklet products are semi-durable covers for the surfaces that leading microbiologists at the U.S.

Centers for Disease Control have identified as critical for keeping clean. These surfaces include: patient bed rails, overbed tray tables, bedside tables, staff call handsets, patient room light switches and door levers.

The Tactivex line will also feature a product for nurse stations and areas that serve as pivot points of activity between patient room visits. Sharklet will also be applied to children’s backpacks, suitcases and yoga mats.

Kenneth K. Chung, James F Schumacher, Edith M Sampson, Robert A Burne, Patrick J Antonelli, Anthony B Brennan, “Impact of engineered surface microtopography on biofilm formation of Staphylococcus aureus,” Biointerphase, June 1,, 2007 sharklet.com

Tomorrow’s solution: Compostable  baler twine

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