Self-Propelled Tubular Micromotors Powered by Hydrogen Bubbles under Mild Conditions: A Major Step toward Biological Applications with Live Cells

Polymer-based tubular micromotors, featuring an inner layer of Pt nanoparticles (PtNPs), exhibit vigorous propulsion by emitting H2 bubbles in an aqueous ammonia borane (NH3BH3) solution. The hydrolysis of NH3BH3 on the PtNPs facilitates the continuous release of H2 gas from the open-end terminus, driving its forward movement. Unlike conventional O2 bubbles' systems that rely on hydrogen peroxide (H2O2) as fuel, these micromotors can operate in the presence of live cells within the NH3BH3 medium. Consequently, micromotors functionalized with the lectin concanavalin A demonstrate the capability to capture and release Escherichia coli (E. coli) without inducing cell death. Remaining bacteria can be detected by using standard culture techniques. Conversely, micromotors coated with TiO2 nanoparticles enable photosterilization of E. coli without fuel-induced damage. The self-stirring motion of the tubes enhances both bacterial capture and sterilization efficiency. These advancements obviate the necessity for H2O2 as a fuel source, and pave the way for the applications of micromotors in biological contexts.