Ultralow fouling polyacrylamide on gold surfaces via surface-initiated atom transfer radical polymerization

In this work, polyacrylamide is investigated as an ultralow fouling surface coating to highly resist protein adsorption, cell adhesion, and bacterial attachment. Polyacrylamide was grafted on gold surfaces via surface-initiated atom transfer radical polymerization (ATRP). Protein adsorption from a wide range of biological media, including single protein solutions of fibrinogen, bovine serum albumin, and lysozyme, dilute and undiluted human blood serum, and dilute and undiluted human blood plasma, was studied by surface plasmon resonance (SPR). Dependence of the protein resistance on polyacrylamide film thickness was examined. With the optimal film thickness, the adsorption amount of all three single proteins on polyacrylamide-grafted surfaces was <3 pg/mm(2), close to the detection limit of SPR. The average nonspecific adsorptions from 10% plasma, 10% serum, 100% plasma, and 100% serum onto the polyacrylamide-grafted surfaces were 5, 6.5, 17, and 28 pg/mm(2), respectively, comparable (if not better) than the adsorption levels on poly(ethylene glycol) (PEG) and zwitterionic poly(sulfobetaine methacrylate) surfaces, the best antifouling materials known to date. The polyacrylamide-grafted surfaces were also shown strongly resistant to adhesion from bovine aortic endothelial cells and two bacterial species, Gram-positive Staphylococcus epidermidis ( S. epidermidis ) and Gram-negative Pseudomonas aeruginosa ( P. aeruginosa ). Strong hydrogen bond with water is considered the key attribute for the ultralow fouling properties of polyacrylamide. This is the first work to graft gold surfaces with polyacrylamide brushes via ATRP to achieve ultralow fouling surfaces, demonstrating that polyacrylamide is a promising alternative to traditional PEG-based antifouling materials.