Abstract
Magnetic soft robots have the potential to revolutionize the field of drug delivery owing to their capability to execute tasks in hard-to-reach regions of living organisms. Advancing their functionality to perform active drug delivery and related tasks necessitates the innovation of smart substrate materials that satisfy both mechanical and biocompatibility requirements while offering stimuli-responsive properties. Optimization of the interaction between the substrate and magnetic components is also critical as it ensures robust actuation of the robot in complex physiological environments. To address these issues, a facile strategy is presented that synergistically combines genetic programming and electrochemical engineering to achieve on-demand drug release with protein-magnetite soft robots. As the substrate of the robot, genetically engineered silk-elastin-like protein (SELP) is encoded with thermo-responsive motifs, serving as the dynamic unit to respond to temperature changes. Ultrafine magnetite (Fe(3)O(4)) nanocrystals are electrochemically nucleated in situ and grown on Fe-protein coordination sites within the SELP hydrogel network, endowing reinforced mechanical strength, superparamagnetic property, and photothermal conversion capability. These soft robots can navigate confined spaces, target specific sites, and release drug payloads ex vivo in an intestinal model. Taken together, the proposed strategy offers an innovative approach to tailoring protein-based soft robots toward precision drug delivery systems.