Synthesis and characterization of a novel ZnO/HAp Nanocomposites for Enhanced Enamel Biomineralization

Abstract

Introduction: Hydroxyapatite (HAp), as the principal inorganic constituent of enamel, dentin, and cementum, has been extensively investigated as a remineralizing scaffold. Zinc oxide (ZnO) nanoparticles confer synergistic antibacterial, anti-inflammatory, and osteoconductive properties that augment the therapeutic index of HAp-based biomaterials.

Objectives: This study aim to synthesize and characterize ZnO/HAp nanocomposites, and to evaluate their efficacy in promoting enamel biomineralization.

Methods: ZnO nanoparticles were fabricated via a sol–gel route employing zinc nitrate as the molecular precursor, followed by controlled hydrolysis, condensation, and high-temperature calcination. HAp was synthesized through a wet chemical precipitation protocol using calcium nitrate and orthophosphoric acid under alkaline conditions. The resultant nanocomposite was prepared at predetermined weight ratios by ultrasonication-assisted blending.

Results: SEM analysis revealed that demineralized enamel surfaces, characterized by a disorganized, highly porous architecture consistent with mineral depletion, were transformed into densely packed, plate-like and needle-shaped crystalline assemblies following nanocomposite treatment, indicative of de novo hydroxyapatite nucleation and enamel-like microstructural restoration. FTIR spectroscopy confirmed the presence of principal phosphate (PO₄³⁻) and carbonate (CO₃²⁻) stretching modes, along with hydroxyl (–OH) absorbance, collectively corroborating the formation of stoichiometrically coherent apatite.

Conclusions: ZnO/HAp nanocomposites were successfully synthesized and demonstrate potent remineralizing capacity, excellent hemocompatibility, and multifunctional biological activity. These properties establish ZnO/HAp nanocomposites as promising candidates for next-generation preventive and restorative dental biomaterials.