Organic therapeutic component-modified carbonated apatite and biopolymer composites for next-generation implant coatings

The integration of bioactive ceramics with biopolymers represents a frontier in the development of advanced materials for tissue engineering. This study investigates the synthesis and characterization of novel organic therapeutic component-modified carbonated apatite (cAp) composites blended with biopolymers. Carbonated apatite was prepared using a wet chemical precipitation method. Subsequently, the cAp was functionally modified by incorporating therapeutic components: organic strontium (Sr 2+ ), magnesium (Mg 2+ ), and zinc (Zn 2+ ). The resulting functionalized cAp powder (fcAP) was then integrated into two distinct biopolymer matrices: polycaprolactone (PCL) and cellulose acetate (CA). The resulting composites were successfully deposited as non-continuous coatings or clusters onto a rough metallic implant surface. These layers exhibited a highly porous three-dimensional microstructure, which is beneficial for enhanced cell adhesion. Comprehensive physicochemical characterization, utilizing techniques including Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (SEM-EDX), Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), and Fourier-Transform Infrared Spectroscopy (FT-IR), confirmed that the synthesized calcium phosphate phase was carbonated apatite and verified the successful incorporation and presence of the therapeutic elements. Quantitative analysis of the therapeutic fcAp revealed a Ca to P molar ratio of 1.60, which closely approximates that of natural bone. The composite coatings significantly enhanced the corrosion resistance of the metallic substrate, achieving a 20-46% reduction in the corrosion rate compared to bare titanium. After one month of immersion testing, the two biopolymer composites exhibited distinct degradation behaviors: PCL-fcAp showed a slight weight loss of 0.5%, while the CA-fcAp demonstrated exceptional hydrolytic stability, presenting a minimal weight loss of less than 0.15%.