Composite chitosan-based nanoparticles as a basis for innovative antimicrobial coating for bioprosthesis: Preparation and application using carbonic acid as a “green” self-neutralizing solvent

Abstract

Firmly bonded antimicrobial protective coating of biomatrix significantly enhances functionality of medical devices, in particular bioprostheses, for example, bioprosthetic heart valves in cardiac surgery. In our work, we have obtained a special coating based on chitosan nanoparticles (including those doped with Ag nanoparticles) that were obtained and single–step applied using a biocompatible and self -neutralizing carbonic acid as a polymer solvent. This approach makes it possible to obtain a biomatrix with a covalently bonded polymer screen of nanoparticles, which, in turn, can be doped with antimicrobial agents. For the first time ever, it has been demonstrated that one can form chitosan nanoparticles in solutions in carbonic acid, which are even more stable than in a classical solvent with a higher zeta potential (|ζ|∼35 mV). Moreover, a highly-accurate analysis using a tritium labelling technique shows a fourfold increase in the deposition of nanoparticles compared to the deposition from conventional solvent. Using a high-resolution microscopy, it was possible to identify an ultra-thin coating of polymer spherical nanoparticles (∼50 nm) clinging to collagen fibrils. Analysis of antimicrobial activity shows a possibility of induced antimicrobial response due to changes in conformation of polymer nanoparticles and release of antimicrobial agents in case of pathogen growing on the bioprosthesis. A threefold increase in strength of the bioprosthesis due to coating has been identified.