Biohybrid magnetic carrier robots for targeted bacteria release in ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by persistent inflammation and ulcers in the colon and rectum. Notably, UC is commonly associated with microbial dysbiosis while bacterial therapies often fail to achieve durable, site-specific colonization. Here, we develop a biohybrid magnetic carrier robot (MCR) platform that delivers bacteria along programmed trajectories and enables prolonged retention at target sites. The MCR is structured with a thin layer of hard-magnetic soft material that responds sensitively to magnetic fields, and a functional layer of bacteria-loaded hydrogel that preserves bacterial viability and release probiotics at specific pH values. This multi-material system is created via a multi-layer screen-printing technique, which allows precise patterning of functional materials at the submillimeter scale and holds promise for scalable production. Precise wireless navigation is validated in simulated environments using a robotic-arm-assisted magnetic driving system. In vivo studies in mice show that MCR-assisted treatment accelerates clinical recovery, significantly increases gut microbial diversity, and mitigates colon damage. In a DSS-induced acute colitis mouse model, the biohybrid magnetic carrier robots improved body-weight recovery, disease activity, colon length, and histological morphology relative to the disease model and material-only controls, while several outcomes also improved relative to free bacteria-loaded hydrogel. Fecal 16S rRNA gene sequencing further showed increased microbial richness and diversity and a shift toward a more control group community configuration after MCR based bacterial treatment. This controllable delivery strategy provides a modular and versatile platform for bacterial therapies in UC, expanding its translational potential toward the treatment of intestinal diseases and the modulation of gut health.