Eco-friendly synthesis of eggshell-derived nano-hydroxyapatite: physicochemical characterization, hemocompatibility, and bone regeneration potential

Hydroxyapatite (HA) nanoparticles synthesized from bio-waste sources like eggshells offer a sustainable and biocompatible alternative for bone regeneration. This study successfully synthesized nano-hydroxyapatite from chicken eggshell-derived calcium precursors and comprehensively characterized it. X-ray diffraction (XRD) confirmed the formation of a highly crystalline, phase-pure HA structure, while Fourier-transform infrared spectroscopy (FTIR) revealed characteristic phosphate, hydroxyl, and carbonate bands, resembling biological apatite. Scanning electron microscopy (SEM) showed spherical nanoparticles (~ 11.2 nm) with uniform distribution, enhancing bioactivity. Hemocompatibility assays demonstrated concentration-dependent hemolysis, with minimal RBC disruption (< 7%) at 12.5 mg/ml, mitigated further by protein corona formation. In vitro studies revealed excellent osteoblast (MC3T3-E1) adhesion and spreading on HA surfaces, indicating osteoconductivity. Additionally, HA nanoparticles exhibited dose-dependent free radical scavenging activity (up to 84.7% at 200 µg/ml) and significantly suppressed pro-inflammatory cytokines (IL-1β and IL-18) in LPS (Lipopolysaccharide)/ATP (Adenosine triphosphate)-stimulated macrophages, highlighting anti-inflammatory potential. These findings collectively underscore the suitability of eggshell-derived nano-HA for bone tissue engineering, combining eco-friendly synthesis, structural biomimicry, and multifunctional bioactivity to promote osteogenesis and mitigate inflammation.