Biologically Active Hyaluronic Acid-Conjugated Zn, Se-Doped Hydroxyapatite Nanobiocomposite: Integrated Insights into Protein Adsorption and Cellular Interactions.

The therapeutic efficacy of growth factor-mediated bone regeneration is frequently compromised by structural destabilization and loss of bioactivity following adsorption onto biomaterial surfaces. Addressing this challenge requires biomaterials capable of not only delivering osteogenic cues but also preserving protein functionality at the nanobiointerface. Herein, a hyaluronic acid-conjugated Zn, Se codoped hydroxyapatite nanobiocomposite (HA-Zn, Se-HAP) was engineered to investigate the molecular determinants governing growth factor stabilization and cellular response. Zn and Se incorporation modulated the apatite lattice and surface reactivity, while hyaluronic acid established a hydrated extracellular matrix-mimetic interface conducive to protein interaction. Using BMP-2 as a model osteogenic growth factor, spectroscopic, calorimetric, and computational analyses revealed a thermodynamically favorable and reversible adsorption process dominated by hydrogen bonding, electrostatic interactions, and desolvation effects, while preserving the native conformational architecture of the protein. Density functional theory (DFT) and molecular docking further elucidated the electronic redistribution, binding orientation, and intermolecular interaction motifs responsible for BMP-2 stabilization. The nanobiocomposite exhibited excellent cytocompatibility toward both L929 fibroblasts and MG-63 osteoblast-like cells, promoting cellular metabolic activity, proliferation, and collagen-rich extracellular matrix formation. The findings presented herein reveal the critical role of nanobiointerface engineering in governing growth factor adsorption, structural preservation, and downstream cellular behavior. By bridging interfacial physicochemistry with biological function, this work provides fundamental mechanistic insight into growth factor-biomaterial interactions and advances the design of bioactive osteoinductive platforms that extend beyond conventional carrier systems toward the active modulation of protein fate and regenerative outcomes.