Biotemplated Photocatalytic Micromotors for Effective Inhibition of Bacterial Growth

Bacterial infections represent a major threat that can cause millions of deaths worldwide, where bacterial species can colonize and grow into highly resistant biofilms. Autonomous micromotor propulsion can improve the overall efficiency of bacterial growth inhibition versus other static processes, leading to novel methods for bacterial treatment. Here, biotemplated magnetic and photocatalytic micromotors are synthesized using E. coli and S. aureus as bacterial templates with different morphological features, such as shape and size, to obtain reproducible micromotors, followed by decoration with Fe₃O₄ nanoparticles for magnetic guidance into biofilms. Then, photoactive BiOCl crystals are grown on the micromotor surface for in situ photocatalytic generation of reactive oxygen species (ROS) for efficient bacterial growth inhibition. Thanks to their high photostability, E. coli@Fe₃O₄@BiOCl micromotors enabled controlled and efficient ROS production under sterilization conditions by using 375 nm light to trigger an oxygen vacancy generation mechanism within a biocompatible, tailored 3D-printed electrochemical cell. The (photo)-electrochemical ROS generation correlated well with highly efficient bacterial growth inhibition, demonstrating the potential application of the collective dynamics of these multifunctional biotemplate-based micromotors. The concepts described here are promising for the development of future strategies against resistant bacteria by understanding the underlying processes behind them.