MOF-based magnetic microrobot swarms for pH-responsive targeted drug delivery

Metal-organic frameworks (MOFs) hold significant potential as vehicles for drug delivery due to their expansive specific surface area, biocompatibility, and versatile attributes. Concurrently, magnetically actuated micro/nano-robots (MNRs) offer distinct advantages, such as untethered and precise manipulation. The fusion of these technologies presents a promising avenue for achieving non-invasive targeted drug delivery. Here, we report a MOF-based magnetic microrobot swarm (MMRS) for targeted therapy. Our approach overcomes limitations associated with a single MNR, including limited drug loading and the risk of loss during manipulation. We select Zeolitic Imidazolate Framework-8 (ZIF-8) as the drug vehicle for its superior loading potential and pH-sensitive decomposition. Our design incorporates magnetic responsive components into the one-pot synthesis of Fe@ZIF-8, enabling collective behaviors under actuation. Tuning the yaw angle of alternating magnetic fields and nanoparticles' amount, the MMRSs with controllable size achieve instantaneous transformation among different configurations, including vortex-like swarms, chain-like swarms, and elliptical swarms, facilitating adaptation to environmental variations. Transported to the subcutaneous T24 tumor site, the MMRSs with encapsulated doxorubicin (DOX) automatically degrade and release the drug, leading to a dramatic reduction of the tumor in vivo. Our investigation signifies a significant advancement in the integration of biodegradable MOFs into microrobot swarms, ushering in new avenues for accurate and non-invasive targeted drug delivery.