Tuning physicochemical and biological properties of chitosan through complexation with transition metal ions.

The synthesis of biologically active scaffolds is focused on the design of cell-sensitive surface by applying cell-adhesive proteins or bioceramic micro (nano) particles. The emerging new strategy for manipulating the biological properties lies in the modification by trace metals found in the living organism. In this work, we have prepared biocompatible chitosan hydrogels modified by copper (II) and zinc (II) ions through complexation interactions. Due to the strong affinity of metal ions towards amino groups of chitosan, we obtained defined and ordered structures of metal ion-chitosan hydrogel without the formation of additional metal species. The physical and biological properties of complex hydrogels varied in metal ion concentration-dependent manner, from less stable cytocompatible to more stable cytotoxic structure for copper-chitosan system. Interestingly, zinc-chitosan complex hydrogels did show lower stability, but significantly higher biocompatibility with respect to the copper-containing hydrogels.