Magnetically Powered Microrobotic Swarm for Integrated Mechanical/Photothermal/Photodynamic Thrombolysis.

ABSTRACT

Current thrombolytic drugs exhibit suboptimal therapeutic outcomes and potential bleeding risks due to their limited circulation time, inadequate thrombus penetration, and off-target biodistribution. Herein, a photosensitizer-loaded, red cell membrane-encapsuled multiple magnetic nanoparticles aggregate is successfully developed for integrated mechanical/photothermal/photodynamic thrombolysis. Red cell membrane coating endows magnetic particles with prolonged blood circulation and superior biocompatibility. Under a preset rotating magnetic field (RMF), the aggregate with asymmetric magnetic distribution initiates rolling motion toward the blood clot interface, and because of magnetic dipole-dipole interactions, the aggregate tends to self-assemble into longer, flexible chain-like microrobotic swarm with powerful mechanical stir forces, thereby facilitating thrombus penetration and mechanical thrombolysis. Moreover, precise magnetic control enables targeted photosensitizer accumulation, allowing effective conversion of near-infrared (NIR) light into heat and reactive oxygen species (ROS) for thrombus phototherapy. In thrombolysis assays, the weight of thrombi is massively reduced by ≈90%. The work presents a safer and more promising combination of magnetic microrobotic technology and phototherapy for multi-modality thrombolysis.