Antioxidative single atomic nanocatalysts facilitate orally administered probiotic inulin gels for acute colitis amelioration

Acute colitis is characterized by the microenvironment with a high level of inflammation, oxidative stress as well as a disordered microbiome. Sustained delivery of the therapeutic medicine into the colitis foci is limited due to the harsh condition of the gastric environment and fast excretion kinetics in the gut. Herein, we have designed an orally administrable probiotic inulin gel (igel) containing living Bacillus subtilis (B. subt) engineered with outperformed antioxidative single manganese atomic nanocatalyst (SAM NCs) for effective, sustained, and biocompatible therapeutics against acute colitis. Based on the multi-catalytic antioxidative activities (superoxide dismutase, glutathione peroxidase, and catalase) of the synthetic SAM NCs, these nanocatalysts are capable of eliminating the oxidative stresses both in vitro and in vivo. With further engineering onto the living Bacillus subtilis and subsequent in situ gelation inside the inulin, the as-formed probiotic igel(SAM NCs@B. subt) could effectively target and colonize inside the colon region, triggering the in vivo anti-inflammatory, anti-oxidative and gut microbiome modulation performance with high biocompatibility. The present study provides a promising probiotic gelation therapeutic strategy against acute colitis, shedding light on the exploration and clinical transformation of gastrointestinal disease.