Messersmith and Barron wanted to use this durability of peptoids to the antifouling coating's advantage. They proceeded to intelligently design a new polymer made up of two parts, both playing a key role: a short peptide that is the synthetic version of the sticky dihydroxyphenylalanine (DOPA) molecule that gives mussels their adhesive or anchoring strength and a longer peptoid polymer resembling the structure of polyethylene glycol (PEG), a widely studied antifouling polymer.
"We had a rich chemistry available to us when designing this polymer," said Messersmith. "The chemical characteristics of the antifouling component are similar to polyethylene glycol but it lasts longer because it is a peptoid and enzyme resistant. Plus, the structure of the polymer's backbone, which is based on a natural peptide, should make it very biocompatible and prevent evoking an immune response in the body."
The researchers tested their coating on titanium dioxide (a material common in medical implants) in environments that simulated physiologic conditions with fresh serum and cells. The coating anchored itself firmly to the surface and demonstrated excellent resistance to proteins and cells during the five-month experiment. For the same reason the coating is cell and protein resistant, it should also prove to be bacteria resistant, Messersmith said.