Plant Extract-Mediated Valorization of Eggshell Waste into a Multifunctional CuO−ZnO/HAP Biocomposite for Sustainable Biological and Photocatalytic Applications

A multifunctional CuO−ZnO/hydroxyapatite biocomposite was synthesized through a microwave-assisted green route using Drynaria quercifolia rhizome extract and eggshell-derived hydroxyapatite. X-ray diffraction confirmed the successful incorporation of CuO−ZnO nanoparticles onto hexagonal HAP. The biocomposite exhibited enhanced visible-light absorption with a reduced band gap of 2.3 eV. BET analysis revealed a transitional porous structure with a surface area of 31.944 m2 g−1 and pore diameter of 1.901 nm. The biocomposite displayed dose-dependent antimicrobial activity and exhibited good biocompatibility toward L929 fibroblast cells along with enhanced cell migration behavior in wound scratch assay. Preliminary α-glucosidase inhibition results indicate potential antidiabetic activity. Under visible-light irradiation, 94.7% Congo red degradation was achieved within 110 min and followed pseudo-first-order kinetics (k = 0.02558 min−1) and optimal performance at 50 mg catalyst dosage and pH 7. Phytotoxicity studies showed complete seed germination, normal chlorophyll a and b content, and healthy growth of Vigna radiata irrigated with degraded water, confirming effective detoxification and environmental safety.