Co-loading and intestine-specific delivery of multiple antioxidants in pH-responsive microspheres based on TEMPO-oxidized polysaccharides.

In this study, pH-responsive microspheres loaded with multiple antioxidants were developed for intestine-specific delivery and exhibited synergistic activity. They consist of chitosan (CS)-coated microspheres made of TEMPO-oxidized Konjac glucomannan (OKGM) polymers, of which the carboxyl (COO-) groups are cross-linked via ferric ions (Fe3+), allowing the hydrophobic (β-carotene) and hydrophilic (anthocyanins) antioxidants to be simultaneously incorporated. CLSM images showed successful co-encapsulation of β-carotene and anthocyanins. The in vitro release kinetics of co-loaded CS-OKGM microspheres in simulated GI fluids indicated that the microspheres retain the dual antioxidants in an acidic gastric environment and release them at intestinal pH. Free radical scavenging experiments demonstrated that multiple antioxidants loaded into OKGM system had synergistic activity with enhanced stability against heat. The multi-functional CS-OKGM microspheres showed great potential for multiple antioxidants and intestine-specific delivery with enhanced stability.