Fabrication of enzyme-responsive composite coating for the design of antibacterial surface.

In this study, a type of bacteria enzyme-triggered antibacterial surface with a controlled release of Ag ions was developed. Firstly, chitosan-silver nanocomposites (Chi@Ag NPs) were in situ synthesized via using ascorbic acid as reducing agent. Chi@Ag NPs were characterized by transmission electron microscopy, ultraviolet-visible spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Subsequently, Chi@Ag NPs and hyaluronic acid (HA) were used to fabricate antibacterial composite coating via Layer-by-Layer (LBL) self-assembly method. The successful construction of Chi@Ag NPs/HA composite coating was confirmed by scanning electron microscopy, energy dispersive spectroscopy and contact angle measurements, respectively. Then, the amount of released Ag ion was analyzed by inductively coupled plasma atomic emission spectrometry, which demonstrated that the release of Ag ions from the surface could be triggered by enzyme (e.g. hyaluronidase). A series of antibacterial tests in vitro, including zone of inhibition test, bacterial viability assay, antibacterial rate measurement and bacteria adhesion observation, demonstrated that the enzyme-responsive surface could inhibit the growth of bacteria. On the whole, this study provides an alternative approach for the fabrication of antibacterial surfaces on synthetic materials in various fields with the minimal side effects on surrounding environment and human body.