Maleic Acid-Grafted Poly(vinylpyrrolidone) Hydrogels Synthesized by Gamma Radiation for pH-Responsive Drug Delivery

Poly(vinylpyrrolidone) hydrogels net(PVP) were synthesized by gamma radiation at a dose rate of 11.8 kGy h^-1 and subsequently functionalized with maleic acid (MA) via radiation-induced grafting using the direct method to obtain pH-responsive hydrogels for the loading and controlled release of bioactive compounds. Under the selected conditions, MA grafting reached approximately 18%. The obtained hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR-ATR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and swelling studies. The results confirmed the successful incorporation of MA into the hydrogel network and demonstrated that grafting imparted pH-responsive behavior due to the ionization of carboxylic acid groups, yielding two critical pH values at 4.4 and 6.0. Loading and release studies using naringin and benzalkonium chloride showed that the grafted hydrogels exhibited enhanced loading capacity and sustained release profiles governed by the hydrogel network and by interactions between the loaded compounds and the carboxylic groups from MA. Furthermore, hydrogels loaded with antimicrobial agents effectively inhibited the growth of Escherichia coli and Staphylococcus aureus. These findings demonstrate that gamma radiation-induced MA grafting is an effective strategy for developing pH-responsive PVP hydrogels with potential applications as multifunctional wound dressing materials.