Investigating the osteogenic potential of bone-targeted daidzein loaded hydroxyapatite nanoparticles for postmenopausal osteoporosis: pharmacodynamic, biochemical, and genotoxicity evaluations

Bisphosphonates and Hormone Replacement Therapy are the primary therapeutic interventions for Postmenopausal Osteoporosis (PMO), however, associated repercussions limit their usage. To address this challenge, we hypothesised the co-delivery of hydroxyapatite (HAP) with daidzein (DZ) for synergistic treatment of PMO. Propounding this bimodal approach, daidzein-loaded hydroxyapatite nanoparticles (DZHAPNPs) were prepared leveraging the oestrogenic properties of DZ while utilising HAP to facilitate biomineralization. The osteogenic potential of developed nanoparticles was validated through <i>in vitro</i> experiments on MG-63 cells and <i>in vivo</i> studies employing a "4-vinyl cyclohexene diepoxide-induced menopausal-mice model". DZHAPNPs exhibited pronounced pro-osteogenic activity, evidenced by enhanced (155.49%) alkaline phosphatase (ALP) activity in MG-63 cells. Additionally, cellular uptake studies confirmed their internalisation and targeted delivery. Following menopause induction and treatment, the mice underwent radiography, histology, micro-computed tomography (micro-CT) analysis, and biochemical evaluations. A significant reduction (<i>p</i> < 0.001) in biomarkers i.e., β-CTx, BALP, and TRAP-5b, post-treatment showed a substantial influence of DZ and DZHAPNPs. Better bone architectural parameters and bone mineral density in micro-CT analysis served as proof of the hypothesis. Also, the cellular biocompatibility of nanoparticles was confirmed through genotoxicity tests performed on the <i>Drosophila melanogaster</i>. The noteworthy results of the research substantiated the synergistic influence of DZ and HAPNPs in resilience and bone strength maintenance.