Synthesis and Characterization of Metal-doped Chitosan-Hydroxyapatite Composites for the Tuning of Properties: Evaluating Antibacterial Activity and Drug Release

Abstract

The search for versatile, sustainable composites with enhanced antibacterial properties has been driven by the rising threat of antibiotic-resistant diseases and the need for advanced biomaterials for medication delivery. This work involves the synthesis and thorough characterization of chitosan-hydroxyapatite (CS-HAp) composites derived from snail and shrimp shells, respectively, doped with copper (Cu²+) and zinc (Zn²+) nanoparticles. A series of chemical processes, including demineralization, deproteinization, deacetylation, and calcination, was used to produce these composites. Metal doping was incorporated during the fabrication process. Fourier-transform infrared and X-ray diffraction analyses confirmed the successful integration and interaction of CS, HAp, and metal ions, and the crystalline structure remained intact during drug loading and release. Antimicrobial tests showed modest antibacterial activity, predominantly against Gram-positive Staphylococcus aureus, with increased effectiveness at higher metal ion concentrations. Thermogravimetric analysis demonstrated excellent heat stability. Specifically, in Zn-doped samples, drug release in simulated bodily fluid exhibited an initial rapid phase (80%–90% within 50 h), followed by sustained release. Overall, CS, HAp, and metal ions work synergistically to provide biocompatibility, structural integrity, and controlled drug delivery, as shown by the data.