Thiol-Reactive Polymers for Titanium Interfaces: Fabrication of Antimicrobial Coatings

Infection associated with surgical implants is a major cause of their failure. Often in such cases, the implant has to be removed and replaced, which causes undesirable patient discomfort and complications. Bacterial adhesion and growth on implant surface is the primary reason for such infections. Among the approaches to prevent implant associated infections, the conjugation of antimicrobial peptide (AMP) onto the surface of the implant is a very promising approach. In this study, we describe a facile method for the surface modification of titanium (Ti), a widely used material in dental and orthopedic implants, to prevent bacterial adhesion and growth. Thin polymeric films were synthesized on the Ti surface by using a copolymer containing the maleimide group as a thiol-reactive handle to enable the conjugation of AMPs. Robust attachment of the polymeric coating on Ti surfaces was ensured through installation of catechol moieties on the polymer as surface anchoring groups and the variation of the amount of thiol-reactive maleimide group on titanium surfaces. As a proof of concept, to demonstrate a viable application of such thiol reactive surfaces, the antimicrobial peptide E6 (RRWRI­VVIRVRRC) was immobilized onto these well-characterized thin polymeric layers through Michael addition. The antimicrobial activity of peptide-modified surfaces was screened against both Gram-positive and Gram-negative bacteria. The hydrophilic polymer coatings decreased the bacterial adhesion, and the immobilized peptide killed >80% of the adhered bacteria. The developed surface modification method has broad applicability in terms of the choice of substrates and peptides in the design of bioactive surfaces.