Sharklet (material)

Sharklet is a bio-inspired material that was invented by Dr. Anthony Brennan, a materials science and engineering professor at the University of Florida, while working to improve antifouling technology for ships and submarines at Pearl Harbor.[2]

Brennan noticed that sharks do not get fouled. He discovered that shark skin denticles are structured in a characteristic diamond repeating micro-pattern with millions of small ribs[2] at the micrometre scale. His mathematical model for the texture of a substance that would deter microorganisms from settling corresponds to the width-to-height ratio of shark denticle riblets. When compared to smooth surfaces,[3] the first test revealed an 85% reduction in green algae settlement.

Sharklet's texture is a combination of “ridge” and “ravine” at a micrometer scale.

Adherence prevention and translocation restriction have been demonstrated, and are believed to contribute significantly to restrict the risk of device-associated infections.

Sharklet's topography creates mechanical stress on settling bacteria, a phenomenon known as mechanotransduction. Nanoforce gradients caused by surface variations induces stress gradients within the lateral plane of the surface membrane of a settling microorganism during initial contact. This stress gradient disrupts normal cell functions, forcing the microorganism to provide energy to adjust its contact area on each topographical feature to equalize the stresses. This expenditure of energy is thermodynamically unfavorable for the settler, inducing it to search for a different surface to attach to.[4] Sharklet is made, however, with the same material as other plastics.

The physical arrangement enhances the hydrophobicity of the device surface such that the bacteria attachment energy is insufficient for adherence and/or colonization.

Environmental surface contamination provides a potential reservoir for pathogens to persist and cause infection in susceptible patients. Microorganisms colonize biomedical implants by developing biofilms, structured communities of microbial cells embedded in an extracellular polymeric matrix that are adherent to the implant and/or the host tissues. Biofilms are an important threat to human health as they may harbor large numbers of pathogenic bacteria. Up to 80% of bacterial infections in humans involve microorganisms from biofilms, and biofilm formation on medical devices can lead to nosocomial infections and potentially higher mortality rate.[5] Indwelling of medical devices is associated with high risk of infection, given the abundance of bacterial flora on human skin and the risk of contamination from other sources, The fact that many of the pathogens responsible for these infections are multi-drug-resistant, or even panresistant, has become particularly problematic, with few treatment options being available to Healthcare workers and the industry are seeking safe and effective means to prevent device-associated infections.[6]

Sharklet micro-patterns can be incorporated onto the surfaces of a variety of medical devices during the manufacturing process. This micro-pattern is effective against bio-fouling and microbial attachment and is non-toxic. It therefore has potential to help infection control on medical devices such as per-cutaneous devices. Sharklet micro-patterns have been shown to control the bio-adhesion of a wide range of marine microorganisms, pathogenic bacteria and eukaryotic cells. They reduce S. aureus and S. epidermidis colonization after exposure to a simulated vascular environment by 70% or greater when compared to smooth controls. This micro-pattern similarly reduces platelet adhesion and fibrin sheath formation by approximately 80%.[7] An in vitro study demonstrated that it reduced the colonization of S. aureus and P. aeruginosa bacterial pathogens effectively.[6] Importantly, this infection control was achieved without the aid of antimicrobial agents.

• Antimicrobial polymer
• Bioinspiration
• Micropatterning
• Nanomaterial
• Shark skin

• Technologies Inspired by Sharks
• Srinivasan, Hari (March 26, 2015). "Armor-like shark skin may offer blueprint for defense against superbugs". PBS Newhour. Retrieved March 29, 2015.