The Significant Impact of the Evolution of Porous Architecture in Sol-Gel Processed-Nanoscale ZnO-Bearing Bioactive Glass in a Physiological Environment.

INTRODUCTION: The incorporation of network stabilizer trace elements such as zinc in bioactive glass is an effective strategy to enhance biological response and modulate degradation kinetics. However, the quantitative relation among ZnO concentration, lattice micro-strain, and evolution of dynamic pore during in vitro mineralization remains unclear. METHODS: Bioactive glass (BG) film with different concentrations of ZnO nanoparticles (NPs) were synthesized through sol-gel spray pyrolysis method at 100 °C, followed by thermal treatment at 250 °C. In vitro bioactivity was assessed by 28 days of immersion in Earle's Balanced Salt Solution (EBSS). Crystallographic evolution, elemental composition, microstructural morphology, and pore distribution were examined using X-ray diffraction (XRD), Fourier transform infrared (FTIR), field-emission scanning electron microscopy (FESEM), and energy‑dispersive spectroscopy (EDS). RESULTS: The systematic addition of ZnO NPs controls the matrix dissolution and maintains the integrity of the structure. Quantitative analysis of pore size exhibits large scale degradation of glass matrix in undoped bioactive glass, whereas ZnO NPs embedded BG maintains a controlled micro‑porosity range between 0.4-2.5 μm over 28 days of immersion in EBSS. The value of lattice micro-strain (ε) demonstrates that stability of structure is improved as the concentration of ZnO increases. Furthermore, XRD confirms the progressive nucleation growth of hydroxyapatite (HA) layer, corresponding to characteristic reflection peak at 32.08°. The porous architecture provides high surface area that accelerates rapidly the ion exchange process and nucleation of HA for bone bonding. DISCUSSION: ZnO NPs act as an effective network modifier that rapidly inhibits the collapse of BG matrix and stabilizes the bioactive interface. The quantitative analysis reveals that micro-strain stability and surface pore dynamics are systematically controlled by ZnO doping, which demonstrates an optimized framework for enhanced bone interfacial bonding and tissue engineering applications.