Magnetic Soft Robots for Targeted Bacterial Delivery and Enhanced Tumor Spheroid Disaggregation

Bacterial cancer therapy has great potential due to the mobility of bacteria within tissues and their active function in tumor localization. However, rapid uncontrolled division and off‐target distribution of bacteria hinder their therapeutic use. To enhance the bacteria's targeting ability, bacteria are modified with magnetic materials that respond to external control signals. Nonetheless, this approach still tackles the rapid division of bacteria, their slow locomotion speed, and the control of their localization. Therefore, it is proposed to confine bacteria within a more extensive hydrogel‐based platform that can be controlled with external stimuli. Specifically, a millimeter‐scale magnetic soft robot incorporating probiotic bacteria is reported, which allows for the rapid, concentrated, and targeted delivery of living therapeutics with external alternating magnetic fields. In addition to remaining viable and multiplying within the hydrogel network, the bacteria escape from the robot after one hour and successfully disrupt colorectal tumor spheroids in vitro. Moreover, this robot demonstrates mobility across rough terrain made up of multiple materials and can target a polyp inside a phantom of the colon. Overall, this magnetic soft robotic platform provides a new strategy for a potential targeted cancer treatment based on the concentrated delivery of tens of millions of bacteria.