Magnetic-Driven Wheel-Like Microswarms Based on Mechanical Grinding for Cancer Treatment

Colorectal cancer is a major global health burden and a leading cause of cancer-related mortality. Magnetically driven micro/nanorobots have been widely explored for cancer-related biomedical applications. However, translating these systems into precise physical interventions remains challenging due to undesirable side effects. Here, we report a magnetic-field-controlled wheel-like microswarm system for targeted mechanical grinding of cancer cells. The microswarms consist of a nickel-diamond composite structure, providing magnetic responsiveness and mechanical cutting capability. Their motion can be precisely controlled under external magnetic fields, enabling accurate localization and controlled locomotion. We validated the grinding capability through nanocopper layer removal experiments and further demonstrated its performance in in vitro HeLa cell experiments. We evaluated biosafety through hemolysis, coagulation, and cytotoxicity assays, which indicate acceptable biocompatibility under appropriate conditions. Overall, the wheel-like microswarms provide a physical paradigm for localized cancer cell elimination and may expand the application of micro/nanorobotic systems in precision oncology and biomedical engineering.