3D-printed biodegradable hydrogel microrobots for controlled therapeutic delivery

Precise delivery of therapeutic agents to targeted sites within the body is a significant challenge, especially in complex and confined physiological environments. Magnetically actuated microrobots offer a promising solution by enabling remote, controllable, and minimally invasive navigation; however, most existing microrobotic systems are fabricated from nondegradable materials and lack controlled drug release capability, which significantly limits their clinical translation. Here, we report 3D-printed biodegradable magnetic microrobots based on gelatin methacryloyl (GelMA) hydrogel capable of controlled therapeutic delivery. Using high-resolution direct laser writing, dual-layer GelMA microrobots with distinct crosslinking degrees were fabricated, enabling tunable degradation and controlled release of encapsulated drugs. The low-crosslinked outer shell functions as a protective barrier that prevents premature drug diffusion, while the highly crosslinked inner core enables sustained drug release during enzymatic degradation. The microrobots demonstrate excellent biocompatibility and controllable degradation in cellular environments. In addition, the integration of a biocompatible magnetic skeleton within the GelMA body enhances mechanical stability and enables precise magnetic actuation. This study presents a versatile strategy for developing biodegradable, magnetically actuated microrobots with controlled therapeutic release, offering strong potential for targeted drug delivery, tissue regeneration, and minimally invasive biomedical applications.