Synthesis and characterization of N-guanidinium chitosan/silica ionic hybrids as templates for calcium phosphate...

We report novel materials for calcium phosphate mineralization processes. These materials were synthesized via a three-step procedure starting from chitosan. In a first step, N-guanidinium-chitosan acetate was prepared via a direct guanylation reaction with cyanamide. This intermediate was then used as a cationic polymer substrate for attracting two functional anionic silica precursors, which subsequently allowed accessing new ionic hybrid materials via sol-gel chemistry. These N-guanidinium-chitosan acetate/silica hybrid materials, containing either sulfonate or carboxylate groups, were characterized using solid state ¹³C NMR, ²⁹Si NMR and FT-IR spectroscopy. Finally, these two ionic hybrids were used as templates for in-vitro biomimetic calcium phosphate mineralization using simulated body fluid solution. We could show that the two ionic hybrids act as versatile templates for biomineralization, inducing the formation of hydroxyapatite, as proved from XRD, SEM, EDX, TEM and TGA. The current results suggest that the new ionic hybrids may be promising candidates for bone tissue engineering applications.