Oral delivery of pH-responsive tannic acid microcapsules for the amelioration of DSS-induced colitis

This study developed a novel food-grade, pH-responsive delivery system based on tannic acid (TA)-crosslinked gelatin/gum arabic microcapsules (NPTA) for TA delivery. Optimized fabrication yielded microcapsules with high encapsulation efficiency (95.18%) and bioactive loading (30.21%). NPTA showed pH-responsive release, with minimal gastric leakage and rapid release at colonic pH. Characterization (FTIR, DSC, XRD) confirmed successful TA encapsulation via hydrogen bonding/hydrophobic interactions, yielding an amorphous complex. In a DSS-induced colitis model, NPTA outperformed free TA, significantly improving clinical symptoms (reduced disease activity index, body weight loss) due to enhanced colonic accumulation. Both treatments comparably attenuated core pathologies (pro-inflammatory cytokines, barrier dysfunction); however, NPTA significantly enhanced colonic SOD activity and MUC2 expression. These findings demonstrate that pH-responsive delivery selectively amplifies the bioactivity of TA towards concentration-dependent health-promoting mechanisms. This work establishes NPTA as an effective food-grade strategy to maximize the gut-health benefits of polyphenols through spatiotemporal release control.