Light-controlled microbots gathering as a sterilization platform for highly efficient capturing, concentrating and killing targeted bacteria

Owing to the dispersion of photothermal particles and targeted bacteria, the heat generated by the photothermal effect cannot be completely transferred to the target, resulting in a reduction in the efficiency of traditional photothermal sterilization. Herein, to solve the problem, a new photothermal sterilization platform was successfully developed for capturing and gathering bacteria based on the photothermal effect of microbots. The sterilization microbots were fabricated from carbonized sunflower pollen grains (SPG) with polydopamine (PDA) coating. Bacterial capture molecule, vancomycin, is grafted onto the outer surface of the PDA. Under the focused laser, the PDA/SPG microbot can show positive phototactic motion and bubble-induced gathering powered by photothermal-induced Marangoni effect for efficient capture, concentration, and aggregation the targeted bacteria. Moreover, the gathered microbots can generate higher temperature through photothermal effect to efficiently kill bacteria compared with the dispersed ones. In word, such sterilization microbots could provide a new proof-of-concept perspective on photothermal therapy, and be promising for various sterilization applications.