Preparation and characterization of a biomimetic composite based on biogenic hydroxyapatite and chitosan

A biomimetic composite based on biogenic hydroxyapatite (BHA) and chitosan (CS) with a weight ratio of 70:30, corresponding to the mineral-to-organic ratio of native bone tissue, was successfully prepared in injectable and scaffold forms. The phase composition, microstructure, specific surface area, skeleton density, rheological behavior, injectability, suspension stability, resorption behavior, and cytocompatibility of the composite were investigated. Structural characterization by XRD, FTIR, and SEM confirmed the preservation of the crystalline hydroxyapatite phase, the absence of secondary phases, and a homogeneous distribution of BHA particles within the chitosan matrix. Rheological studies revealed non-Newtonian shear-thinning behavior with an apparent yield stress of ~250 Pa and a multistage hysteretic flow response associated with shear-induced structural rearrangements within the CS–BHA network. Following shear cessation, the viscosity recovered to approximately 80% of its initial value, confirming satisfactory injectability and suitability for minimally invasive administration. Turbiscan analysis demonstrated good physical stability of the injectable suspension and improved stability after 30 days of storage. The material exhibited controlled resorption in physiological saline while maintaining its structural integrity. Cytotoxicity studies revealed a concentration-dependent biological response. Overall, the developed BHA/CS composite combines structural stability, controlled resorption, favorable rheological properties, injectability, suspension stability, and promising biological performance, making it a promising biomimetic material for bone tissue regeneration applications.