An Assessment of Fabrication, Properties, and Medical Applications of Chitosan-Nanometal Coatings.

Chitosan (chit) is a specific polymer, an oligosaccharide, that demonstrates several important properties alone or in combination with other compounds or elements. These important properties include being biocompatible with the human body and simultaneously effective in destroying bacteria. Moreover, it is a smart polymer, as it can change its properties when the pH value decreases below about 7. Therefore, chitosan is widely applied in dermo-cosmetics, but it is also intensively investigated for its use in food preservation and the targeted regeneration of teeth in dentistry. Due to these advantageous characteristics, chitosan has been employed in numerous coating systems for biomedical applications. These coatings can be fabricated through a wide variety of procedures involving different deposition techniques, process parameters, and the chemical characteristics of the environment, solution, air or vacuum, as well as the substrate. Chitosan-metallic coatings have often been investigated; however, the use of elementary metals in the form of nanoparticles (NPs) was rarely reported. The main part of this paper is focused on the presentation of chitosan-metallic NPs, in particular, an application of potentially antibacterial noble and semi-noble metals such as Au, Ag, Cu, and Zn, intensively investigated by the author. The deposition methods and their limitations, the differences in properties of such coatings and those possessing Ag, Sr, Zn, and other metals in the form of cations in chemical compounds, and the perspectives of chit-MeNPs (metal nanoparticles) are thoroughly considered, and future research is proposed.