Laser-Guided Self-Rolled Magnetic Microrobots for Targeted Biofilm Eradication in Severely Infected Medical Stents

Pathogenic bacterial biofilms on biological interfaces and implanted medical devices are highly resistant to conventional antimicrobial therapies, leading to persistent infections and device failure. Magnetically driven micro/nanomotors (MNMs) offer a promising platform for localized drug delivery and in situ biofilm eradication in complex anatomical environments. However, current MNMs face critical challenges, including the serious risks of retention in vivo and insufficient propulsion within viscoelastic biofilms. Here, a laser-guided self-assembly strategy is developed to assemble tubular magnetic micromotors from high-entropy alloy/polyimide (HEA/PI) bilayers for hydrogel-based drug delivery and biofilm eradication inside implantable medical tubes. Programmable direct laser writing converts PI into laser-induced graphene (LIG) while simultaneously inducing controlled self-rolling of the HEA/LIG bilayers into mechanically robust micro-rolls. Under rotating gradient magnetic fields, these micro-rolls display controllable oscillatory-spiral propulsion in confined microchannels, enabling fast transport and site-specific drug release. When filled with an antibiotic-loaded hydrogel, the HEA/LIG micro-rolls achieve synergistic mechanical biofilm disruption and localized antibiotic release within E. coli-infected pancreatic duct stents, resulting in a 97% sterilization efficiency, 44% higher than that achieved by standard chemical sterilization. This work establishes an unprecedented laser manufacturing paradigm for medical micromotors, providing a minimally invasive approach for targeted biofilm removal from hard-to-reach anatomical sites.