Inulin and metal-phenolic network single-cell encapsulation: Boosting the tolerance and intestinal colonization capability of Bifidobacterium lactis

Probiotics play a vital role in human health, but maintaining their high viability during processing and oral administration remains challenging. In this study, we utilized inulin and tannic acid (TA)/Ca²⁺ metal-phenolic networks (MPNs) as coating materials to encapsulate anaerobic Bifidobacterium lactis (BL) using a layer-by-layer self-assembly strategy to improve their tolerance to the adverse gastrointestinal microenvironment and colonization in the intestinal tract. The results demonstrated that the three-dimensional gel coating formed by inulin could protect the MPNs coating from degradation by gastric acid and improve the ability of BL to resist gastric acid and bile salts, significantly increasing the survival rate of probiotics. Additionally, MPNs could effectively scavenge free radicals and resist cell damage caused by oxidative stress. Importantly, TA in MPNs could form strong interactions (hydrogen bonds) with mucin in the intestine, greatly prolonging the residence time of BL (more than 96 h). Moreover, the raw materials used to prepare BL@TA@Inulin are food-grade, thus ensuring high biosafety. In summary, BL@TA@Inulin represents a novel probiotic single-cell encapsulation approach to achieve highly active and adhesive delivery of probiotics, with potential applications in developing healthy foods and treating gastrointestinal tract-related diseases.