Multiscale Magnetic Hydrogel Robot with a Core–Shell Structure for Active Targeted Delivery

Tremendous progress in applying small-scale magnetic robots for targeted drug delivery has sparked a growing interest among researchers. However, significant effort is needed to design and fabricate robots to meet the needs of clinical treatments, such as biocompatibility, biodegradation, and synergistic therapy. Here, we propose a multiscale magnetic hydrogel robot (MMHR) with a core–shell structure in which superparamagnetic nanoparticles and curcumin-loaded chitosan microparticles (CCMs) are encapsulated inside the core, while doxorubicin-loaded chitosan microparticles (DCMs) are embedded inside the shell. The core and shell of the MMHR are composed of pH-sensitive calcium alginate hydrogels that can alleviate the sudden release of drugs from CCMs and DCMs in gastric fluid. MMHRs can be precisely actuated to the target region through magnetic driving systems for further drug delivery. The experimental results demonstrate that the MMHR possesses superior obstacle-crossing ability and can successfully locomote on the surface of the intestine. Additionally, the co-delivery of doxorubicin and curcumin is realized through the different fabrication methods of CCMs and DCMs and shows excellent synergistic therapeutic effects against colon cancer cells. The powerful propulsion, good biocompatibility, and remarkable synergistic efficacy of the MMHR offer a promising route for active drug delivery through the gastrointestinal tract.