ENHANCED TISSUE REGENERATION USING BIOACTIVE HYDROGEL COMPOSITES REINFORCED WITH ZINC OXIDE NANOPARTICLES

Abstract

Hydrogel-based biomaterials are widely used in tissue regeneration, yet their clinical performance is limited by weak mechanical strength, rapid degradation, and insufficient biological bioactivity. This study evaluates bioactive hydrogel composites reinforced with zinc oxide nanoparticles (ZnO-NPs) at concentrations of 1%, 2%, and 3% to improve mechanical stability, antimicrobial activity, and regenerative capacity. Mechanical analysis showed that ZnO-NP incorporation increased compressive modulus from 9.8 ± 1.2 kPa in the control to 41.7 ± 2.8 kPa, reflecting a 325% improvement, while compressive strength increased from 32.5 ± 3.7 kPa to 67.2 ± 4.5 kPa. Swelling behavior decreased from 410 ± 18% to 301 ± 12%, and degradation rate reduced from 58.3 ± 3.4% to 24.8 ± 2.1% over 14 days. Sustained Zn²⁺ release was observed, rising from 0.62 ± 0.05 ppm to 3.94 ± 0.21 ppm across the study period. Biological assays revealed enhanced fibroblast proliferation, increasing from baseline 100% viability to 159 ± 8% at 72 hours in 3% ZnO-NP hydrogels. Antimicrobial testing demonstrated strong inhibition against E. coli (up to 18.2 ± 1.1 mm) and S. aureus (up to 17.5 ± 1.2 mm). In vivo wound-healing analysis confirmed accelerated tissue repair, with wound closure reaching 92.4 ± 3.1% by day 14 compared to 74.2 ± 4.5% in hydrogel-only and 58.6 ± 5.3% in untreated controls. Histologically, ZnO-treated wounds showed a 182 ± 12 μm epithelial layer, 71.5 ± 4.1% collagen density, and 24.6 ± 2.3 microvessels per field. Overall, ZnO-NP hydrogels significantly enhance mechanical, antimicrobial, and regenerative performance, making them strong candidates for advanced wound-healing applications.