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 H ₂ bubbles in an aqueous ammonia borane (NH ₃ BH ₃ ) solution. The hydrolysis of NH ₃ BH ₃ on the PtNPs facilitates the continuous release of H ₂ gas from the open-end terminus, driving its forward movement. Unlike conventional O ₂ bubbles' systems that rely on hydrogen peroxide (H ₂ O ₂ ) as fuel, these micromotors can operate in the presence of live cells within the NH ₃ BH ₃ 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 TiO ₂ 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 H ₂ O ₂ as a fuel source, and pave the way for the applications of micromotors in biological contexts.