Universal Surface-Initiated Polymerization of Antifouling Zwitterionic Brushes Using a Mussel-Mimetic Peptide Initiator

We report a universal method for the surface-initated polymerization (SIP) of an antifouling polymer brush on various classes of surfaces, including noble metals, metal oxides, and inert polymers. Inspired by the versatility of mussel adhesive proteins, we synthesized a novel bifunctional tripeptide bromide (Br<u>Y</u>K<u>Y</u>) that combines atom-transfer radical polymerization (ATRP) initiating alkyl bromide with l-3,4-dihydroxyphenylalanine (DOPA) and lysine. The simple dip-coating of substrates with variable wetting properties and compositions, including Teflon, in a Br<u>Y</u>K<u>Y</u> solution at pH 8.5 led to the formation of a thin film of cross-linked Br<u>Y</u>K<u>Y</u>. Subsequently, we showed that the Br<u>Y</u>K<u>Y</u> layer initiated the ATRP of a zwitterionic monomer, sulfobetaine methacrylate (SBMA), on all substrates, resulting in high-density antifouling pSBMA brushes. Both Br<u>Y</u>K<u>Y</u> deposition and pSBMA grafting were unambiguously confirmed by ellipsometry, X-ray photoelectron spectroscopy, and goniometry. All substrates that were coated with Br<u>Y</u>K<u>Y</u>/pSBMA dramatically reduced bacterial adhesion for 24 h and also resisted mammalian cell adhesion for at least 4 months, demonstrating the long-term stability of the Br<u>Y</u>K<u>Y</u> anchoring and antifouling properties of pSBMA. The use of Br<u>Y</u>K<u>Y</u> as a primer and polymerization initiator has the potential to be widely employed in surface-grafted polymer brush modifications for biomedical and other applications