Supramolecular Assembly of Magnetic Microrobots for Controllable Cell Delivery and Release

Cell therapy has emerged as a highly effective treatment for degenerative diseases in recent years, and micro/nanorobots, with their small size and versatile mobility, have proven to be reliable carriers for active, targeted cell delivery. However, conventional cell delivery strategies rely on preseeded cells on the micro/nanorobots' surfaces, with in situ retention and subsequent release usually achieved by self-degradation of the carrier robots, which greatly limits their applicability and brings additional biosafety concerns. In this study, we propose an innovative approach to control cell capture and release by a microrobot using host-guest supramolecular interactions between azobenzene and β-cyclodextrin. We designed polystyrene microspheres modified with β-cyclodextrin molecules and specific nucleic acid aptamers as a Janus linker microsphere, which were then combined with a three-dimensional-printed (3D-printed) helical microrobot modified with azobenzene. The connection and disconnection between the microrobot and the Janus linker microspheres can be effectively controlled by irradiation with ultraviolet and visible light. The nucleic acid aptamers enable targeted binding to specific cells, facilitating selective capture and on-demand release. We demonstrate that a single microrobot can capture more than 20 cells on average and can be effectively maneuvered using a rotating magnetic field. Under ultraviolet (UV) light control, the system achieved a release rate exceeding 90%. More importantly, the specific recognition capabilities of nucleic acid aptamers, combined with the customizability of micronano 3D printing technology, suggest a promising pathway for the design and assembly of multifunctional cell delivery microrobot systems tailored to specific biological applications based on targeted cell delivery.