Hybrid composite based on chitosan matrix mineralized by polyphasic calcium orthophosphates with enhanced bioactivity and protein adsorption capacity

Abstract

The hybrid composite (HC) based on chitosan (CS) matrix mineralized with polyphasic calcium phosphate (CaP) component was obtained in situ by hydrothermal synthesis and microwave irradiation (MW) at the reaction solution temperature (60 °C) and close to physiological pH values. Changes in the Ca/CS ratio, and the action of MW in the synthesis affect the initial nucleation and the quantitative content of individual CaPs in the HC. X-ray diffraction (XRD) demonstrates the presence of several CaP phases after sintering at 750 °C, which have different resorption ratios. MW induced heating of the reaction mixture compared to classical convection heating significantly affects the properties of the hybrid composite: Young's modulus increases from 517 МPа (under convection) to 780 MPa (under MW), enhances shape stability, decreases the swelling degree. According to Photoluminescence studies, the HC formation is accompanied by CS macromolecules fragmentation caused by the rupture of glycosidic bonds. Increasing Ca/CS promotes more efficient reversible multilayer adsorption of the amino acid Tryptophan, controlled by the CaP component and corresponds to the Freundlich isotherm. In vivo studies demonstrate high biocompatibility of HC with bone tissue due to the presence of polyphasic CaP in the composite, promoting the formation and germination of newly formed bone in the surrounding tissues as early as 30 days after implantation.