Hydrogel encapsulated magnetic nanoparticles as hyperthermic actuators for microrobots designed to operate in the vascular network

Our group has previously demonstrated that magnetic nanoparticles (MNP) embedded in microrobots can be used for propulsion and tracking in the human vascular network while being guided by an MRI platform. Here, we show that the same magnetic nanoparticles can also be exploited to perform various functions including but not limited to hyperthermic drug release actuators. Specifically, we synthesized vascular microrobots by embedding MNP in N-isopropylacrylamide (NIPA) thermo responsive hydrogel. We experimentally demonstrate the decrease in volume of the hydrogel microrobot in response to AC magnetic heating, a property that allows microrobots to adapt to blood vessels of various diameters. This type of hydrogel is not only able to reduce size in response to temperature elevations but it can also be used to release possible therapeutic agents previously trapped within the hydrogel. Here, NIPA hydrogel samples were placed inside an AC magnetic field of 116 Oe at 145 kHz. Temperature elevations as well as change in hydrogel volume were recorded.