pH-responsive double network alginate/kappa-carrageenan hydrogel beads for controlled protein release: Effect of pH and crosslinking agent

Bovine Serum Albumin (BSA) was encapsulated into pH-responsive alginate/kappa(κ)-carrageenan double network hydrogel beads at different pHs and CaCl2/KCl ratios. Controlled release of BSA was performed in the simulated gastric fluid (SGF) and then in simulated intestinal fluid (SIF). Alginate reinforced the mechanical properties while double network with kappa-carrageenan made slow down the release of BSA into SIF. Sulfate groups on kappa-carrageenan improved the resistivity against phosphate buffer solution. Encapsulation and BSA release was manipulated by varying pH and crosslinking concentration. The highest encapsulation efficiency (83–89%) was obtained with the hydrogel beads prepared at the lower pH than isoelectric point of BSA, then 67–72% of them released in SIF in 4–5 h while lower than 10% of BSA released in SGF, hence, protein delivery targeted intestinal was achieved. BSA release exhibited a coupling of diffusion and polymer relaxation mechanism without burst release.