Polydopamine-Mediated Antimicrobial Lipopeptide Surface Coating for Medical Devices

Biofilm formation on medical implants such as catheters is a major issue which needs to be addressed as it leads to severe health care associated infections. This study explored the design and synthesis of a polydopamine-lipopeptide based antimicrobial coating. The coating was used to modify the surface of Ultrathane Catheters. The lipopeptide SL1.15 with an N-terminal cysteine was covalently conjugated to the polydopamine modified catheters via a Michael addition reaction between the thiol moiety in the peptide and the aromatic ring in the polydopamine layer. The immobilization of the peptide on the polydopamine coated catheters was confirmed using water contact angle, X-ray photoelectron spectroscopy, atomic force microscopy, and scanning electron microscopy (SEM). The antimicrobial activity of the coated catheters investigated using drug resistant and clinical strains of Gram-positive (MRSA and S. aureus) and Gram-negative (E. coli, A. baumannii, and P. aeruginosa) bacteria revealed that lipopeptide immobilization inhibited >90% bacterial adhesion to the catheter surface. Additionally, biofilm assays against MRSA and E. coli revealed that the lipopeptide immobilized catheters inhibited >85% bacterial growth after 1 week incubation. Finally, the cytotoxicity profile of the catheters using the human dermal fibroblast, and the human embryonic kidney cell lines demonstrated that the polydopamine-lipopeptide coating was not toxic after 72 h incubation.