pH-Sensitive Zinc Oxide Nanoparticle-Controlled Sodium Alginate/Silica Hydrogel Beads: for Controlled Curcumin Release

This study designed a pH-sensitive carrier regulated by zinc oxide nanoparticles for the delivery of the hydrophobic drug curcumin (Cur). Carboxymethyl cellulose (CMC) was used as a stabilizer and dispersant to synthesize CMC-ZnO nanoparticles via an in situ reaction. These nanoparticles were then mixed with sodium alginate (SA) and immersed in a tetraethyl silicate (TEOS) hydrolysis solution to form sodium alginate/silica-zinc oxide (Ss/CMC-ZnO) composite hydrogel beads. XRD, FTIR, SEM, and UV-vis analyses confirmed the successful synthesis and incorporation of ZnO nanoparticles into the hydrogel beads. Swelling experiments demonstrated that as the concentration of CMC-ZnO increased, when the TEOS molar concentration was 0.205 M, the maximum swelling ratio decreased from 39.83 to 14.03, with the time to reach the maximum swelling ratio extending from 4 to 6 hours. At a TEOS concentration of 0.375 M, the swelling ratio decreased from 26.77 to 12.10, with the swelling time extending from 6 to 7 hours. Hemolysis and cytotoxicity tests confirmed the hydrogel beads' good biocompatibility. Cur was incorporated using a blending method, and in vitro release experiments revealed that the Ss/CMC-ZnO hydrogel beads exhibited excellent pH sensitivity. The addition of CMC-ZnO NPs effectively prolonged the release time of curcumin, indicating potential for applications in controlled drug delivery.