ARLINGTON, Va., May 18, 2005 -- With one side sticky and the other slick, a two-sided coating developed by biomedical engineers has shown promise in the lab for prolonging the life and improving the performance of medical implants.

Medical implants, such as cardiac stents and biosensors, often fall victim to a buildup of bacteria, cells and proteins that accumulate on the surfaces of the devices. This buildup can degrade the implants' performance and threaten patients with infection.

Biomedical engineers at Northwestern University have developed a new type of coating by copying the design of an adhesive protein from mussels and adding a polymer that repels biological molecules.

The sticky side of the coating, designed around the mussel protein, faces inward and adheres firmly to the medical device. The slick side, which faces outward, fends off biological molecules that would otherwise attach and accumulate.

The result is a durable coating that stays clean, said Whitaker investigator Phillip Messersmith, Ph.D., associate professor of biomedical engineering at Northwestern. Findings of the research were published May 13 online by the Journal of the American Chemical Society.

Messersmith and his colleague Annelise Barron, Ph.D., associate professor of chemical and biological engineering, came up with the novel design. They combined the synthetic version of the sticky molecule that mussels use to anchor themselves with a longer polymer resembling polyethylene glycol, a well-known polymer that keeps surfaces clean.

"The new component lasts longer because it resists destruction by the body's enzymes," Messersmith said. "The structure of the polymer's backbone, which is based on a natural peptide of mussels, should make it very biocompatible so the immune system will not attack it."

The researchers applied the new coating to a surface of titanium dioxide and then subjected the coating to cells and proteins similar to those encountered by medical implants. The coating stayed firmly in place and clean for more than five months, a significant period of time for such an experiment.

The Whitaker Foundation supported Messersmith's earlier research in biomaterials through a Biomedical Engineering Research Grant in 1995.

Contact:
Phillip Messersmith, Northwestern University
Frank Blanchard, The Whitaker Foundation