Abstract

Probiotics play a vital role in regulating gut microbiota, strengthening the intestinal barrier, and modulating inflammation. However, their therapeutic efficacy is often compromised by harsh gastrointestinal conditions, rapid intestinal clearance, and lack of targeted delivery, which are particularly evident in ulcerative colitis (UC). To overcome these limitations, we developed a hyaluronic acid (HA)-based hydrogel (EcHA-G) through enzyme-mediated crosslinking of tyramine-functionalized HA and vanillin-modified gelatin. The resulting hydrogel exhibited desirable physicochemical properties, including a porous three-dimensional structure, rapid gelation, ultrafast self-healing, and macrophage-targeting capability. Oral administration of EcHA-G@probiotics markedly enhanced probiotic survival under gastric acid and bile stress by five and seven orders of magnitude, respectively, and significantly prolonged intestinal retention up to 96 h. The system achieved site-specific release, with 16% probiotic release in simulated gastric fluid and 84% in simulated intestinal fluid. In in vivo experiment, EcHA-G@probiotics effectively reduced pro-inflammatory cytokine expression (IL-6 by 82.4%, IL-1β by 96%, and TNF-α by 84.3%), restored the intestinal epithelial barrier, promoted macrophage polarization from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype, and improved gut microbial diversity. Collectively, these results demonstrate that EcHA-G provides a promising oral delivery platform for targeted probiotic therapy and effective colitis alleviation.