Ph-Responsive Gelatin/PEG/Zno Hydrogel Matrix for Controlled Release of Cephalexin: Swelling Behavior, Drug Kinetics, And Antimicrobial Efficacy

This study presents the development and evaluation of a gelatin/polyethylene glycol/zinc oxide (Gel/PEG/ZnO) hydrogel matrix designed for controlled drug delivery applications. The hydrogel was synthesized through the physical blending of gelatin and PEG, followed by chemical crosslinking using glutaraldehyde and the incorporation of zinc oxide nanoparticles (ZnO) to enhance structural stability and antibacterial activity. Swelling behavior was investigated under simulated gastric (SGF, pH 1.2) and intestinal (SIF, pH 6.8) conditions, revealing significant pH sensitivity. The hydrogel exhibited a maximum swelling percentage of 1450% in SIF and 680% in SGF, confirming its suitability for intestinal-targeted drug release. Cephalexin was loaded into the hydrogel matrix, and in vitro drug release studies indicated a sustained release profile, achieving 99.89% release in SIF over 24 hours. Kinetic modeling demonstrated the best fit with the Higuchi model, indicating a diffusion-controlled mechanism. FTIR analysis confirmed successful polymer interaction and drug incorporation, while SEM imaging revealed morphological changes consistent with drug loading. Antibacterial testing showed a 20 mm inhibition zone against Staphylococcus aureus, confirming the synergistic effect of ZnO and cephalexin. These findings suggest that the Gel/PEG/ZnO hydrogel is a promising candidate for pH-responsive, prolonged-release antibiotic delivery systems.