Polydopamine–chitosan coated biofilm-state Lacticaseibacillus paracasei SB27 as a living band-aid for targeted colitis therapy

Inflammatory bowel disease (IBD) involves chronic intestinal inflammation and epithelial barrier disruption. While probiotics offer therapeutic potential, planktonic (PLA) forms suffer from poor viability, limited adhesion, and suboptimal efficacy. Biofilm-state (BIO) probiotics can exert probiotic functions effectively, yet inflammation impairs the conditions necessary for probiotics to form biofilm in the intestine. Direct delivery of biofilm-state probiotics offers a more effective strategy. Here, an innovative probiotic targeted delivery system is developed by integrating biofilm-state Lacticaseibacillus paracasei SB27 with a rationally designed dual-coating composed of polydopamine (PDA) and chitosan (CS) (BIO@PCS). This system enables pH-responsive release of probiotics and selective adhesion to ulcerated colonic sites, mimicking a biological “band-aid”. In DSS-induced colitis model, BIO@PCS achieves superior mucosal targeting and prolonged retention compared to planktonic or uncoated forms. Upon reaching inflamed tissue, the biofilm-state L. paracasei SB27 rapidly forms a bacterial barrier that reinforces all four intestinal barriers and mitigates local inflammation. This approach effectively shields damaged mucosa from further injury and stabilizes the microenvironment. By enhancing both delivery efficiency and therapeutic performance, this strategy represents a dual-optimized, biofilm-based platform for IBD treatment.