Synergistic antibacterial activity of multi components in lysozyme/chitosan/silver/hydroxyapatite hybrid coating

A hybrid coating composed of lysozyme (Lys), chitosan (CS), silver (Ag), and hydroxyapatite (HAp) was constructed on Ti implant to endow this material with highly effective antibacterial activity and biocompatibility through a two-step method. Firstly, CS/Ag/HAp was fabricated on the surface of Ti by electrochemical deposition. Secondly, CS/Ag/HAp was covered by Lys film via spin-coating process in order to further improve the antibacterial efficiency without increasing the content of Ag. X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were employed to investigate the phase formation, surface morphologies and microstructure of the hybrid coatings. Results showed that the as-prepared coating had a hierarchical nanostructure with a uniform distribution of Lys, CS, Ag and HAp. The in vitro antibacterial and cell culture tests revealed that this hybrid coating of Lys/CS/Ag/HAp could not only endow Ti with much higher self-antibacterial efficacy of over 95.28% and 98.02% in 12 h, and still remain sufficiently efficiency of 95.42% and 97.46% after 5 days against Escherichia coli and Staphylococcus aureus, respectively, but also almost be non-cytotoxic. These results suggested that Lys/CS/Ag/HAp-Ti could be a promising biocompatible surface system for metallic implants to resist the bacterial infection for a long time.