The construction of a double-layer colon-targeted delivery system based on zein-shellac complex and gelatin-isomaltooligosaccharide Maillard product: In vitro and in vivo evaluation.

In this study, we developed a double-layer colon-targeted microcapsule. It used the Maillard product of gelatin-isomaltooligosaccharide (GI180) and zein-shellac complex (ZS) as bio-based materials, plant extracts (MPL) and Lactobacillus plantarum JJBYG12 (JJBYG12) were co-encapsulated, endowing them with strong resistance to harsh environments and precise intestinal adhesion and targeting ability. The research results indicated that ZS11 exhibits hydrogen bonding and electrostatic interactions. The encapsulation efficiencies of ZS11 for JJBYG12 and for polysaccharides, polyphenols, and flavonoids in MPL were 88.03 %, 73.40 %, 77.90 %, and 70.87 %, respectively. SEM and CLSM images showed that ZS11 has a dense double-layer structure. Simulation of in vitro gastrointestinal digestion showed that ZS11 can achieve sustained release, with a live bacterial count of 8.05 ± 0.004 Log CFU/mL reaching the colon. The SEM and fluorescence images at different stages of in vitro digestion also demonstrated the strong protective ability of ZS11. Studies conducted in mice had shown that ZS11 can successfully pass through the gastric stage and release probiotics in the distal ileum, cecum, and proximal colon (target intestinal segment). Finally, ZS11 had good storage stability and thermal stability. In summary, this study demonstrated the potential of dual-layer colon-targeted microcapsules for the co-delivery plant extracts and probiotics, providing ideas for developing new delivery systems with targeted therapeutic effects.