Synergistic antioxidant and anti-inflammatory scaffold based on ascorbic acid-enriched hydroxyapatite-PEG-ZnO composite from natural bone waste.

Hydroxyapatite (HAp) derived from bovine bone waste was used to develop a bioactive composite scaffold incorporating polyethylene glycol (PEG), ZnO nanoparticles, and ascorbic acid (AA). This study aimed to fabricate a PEG-based HAp composite enriched with ZnO and AA and to evaluate the influence of these additives on the structural characteristics and biological performance of the scaffold. The resulting HAp-PEG-ZnO-AA composite was designed to provide a sustained release of Zn²⁺ ions while leveraging the antioxidant functionality of AA to enhance biological activity. X-ray diffraction (XRD) analysis indicated that PEG incorporation altered the crystallinity and grain size of HAp, while high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) confirmed the successful integration of ZnO nanoparticles and AA within the HAp matrix. The composite exhibited enhanced antioxidant and anti-inflammatory activity compared to the HAp-PEG-ZnO scaffold without AA, whereas antibacterial performance was primarily attributed to the ZnO component. In vitro cytotoxicity assays using RAW 264.7 macrophage cells demonstrated that the composite was biocompatible at lower concentrations (cell viability > 90% at 6.25 µg mL⁻¹), while higher concentrations resulted in a marked reduction in viability accompanied by observable morphological changes. Overall, these findings suggest that AA incorporation synergistically improves the antioxidant and anti-inflammatory properties of the HAp-PEG-ZnO scaffold without compromising its antimicrobial activity or its biocompatibility at low dosages.