Polydopamine-mediated biointerfacial nanozyme as probiotic protective coating for IBD therapy

Probiotics offer a promising strategy to address the dysfunction of the intestinal mucosal barrier and dysregulation of the gut microbiota in inflammatory bowel disease (IBD). However, the low viability and poor adhesion of probiotics in complex gastrointestinal environments pose significant challenges. To tackle these issues, we designed a specialized protective nano-coating (PDA@CeO 2 ) using biointerfacial phenolic assembly combined with nanozymes for Bifidobacterium bifidum (B.B.). Characteristic peaks of CeO 2 nanoparticles were detected on B.B. via XRD analysis, while SEM and TEM images confirmed the successful attachment of CeO 2 nanoparticles to the probiotic surface. The nano-coating (PDA@CeO 2 ) simultaneously provides B.B. with high adhesion in the intestine, strong tolerance in complex gastrointestinal environments, and the ability to scavenge excess reactive oxygen species (ROS) due to its excellent mucoadhesive ability and high nanozyme activity. Specifically, the protection provided by nano-coating against simulated gastric fluid (SGF, pH 1.2) resulted in cell survival rates approximately 9.4 times higher than those of unprotected B.B. after 1 h of exposure. In IBD mouse models, the combination of PDA@CeO 2 and B.B. demonstrated excellent therapeutic effects, promoting gut barrier repair. Additionally, an increase in Muribaculaceae and Prevotellaceae_UCG-001 and a decrease in Desulfovibrionaceae reshaped the intestinal flora, reducing recurrence. This study highlights the potential of enhancing probiotic functionality through targeted design of protective nano-coatings for IBD therapy.