Alginate-PVA interpenetrating network nanogels: a pH-responsive carrier for thermal stabilization and sustained release of phycocyanin.

Phycocyanin (PC) is a sensitive bioactive protein that suffers from poor thermal stability and premature release in conventional alginate (Alg) hydrogels. In this study, Alg-polyvinyl alcohol (PVA) interpenetrating polymer network (IPN) nanogels were developed as a pH-responsive carrier for improved PC stabilization and controlled oral delivery. Increasing PVA concentration produced nanogels with particle sizes ranging from 174.01 ± 2.66 to 255.02 ± 68.04 nm and significantly improved encapsulation efficiency from 69.59 ± 0.51% to 92.20 ± 0.84%, with a maximum loading capacity of 8.24 ± 0.06%. PVA incorporation also enhanced thermal stability and reduced PC release under simulated gastric conditions (<10% release at pH 1.2), followed by sustained release in simulated intestinal fluid (pH 7.4). Cytocompatibility studies using Caco-2 cells demonstrated acceptable biocompatibility at lower concentrations. Overall, Alg-PVA IPN nanogels provide a promising platform for improving the stability and controlled delivery of sensitive protein-based bioactives.