Human serum albumin (HSA) microtubes with an interior surface composed of Pt nanoparticles (PtNPs) are self-propelled in aqueous H2 O2 medium. They can capture cyanine dye and Escherichia coli (E. coli) efficiently. Microtubes were prepared by wet templating synthesis by using a track-etched polycarbonate (PC) membrane with alternate filtrations of aqueous HSA, poly-l-arginine (PLA), and citrate-PtNPs. Subsequent dissolution of the PC template yielded uniform hollow cylinders made of (PLA/HSA)8 PLA/PtNP stacking layers (1.16±0.02 μm outer diameter, ca. 23 μm length). In aqueous H2 O2 media, the soft protein microtubes are self-propelled by jetting O2 bubbles from the open-end terminus. The effects of H2 O2 and surfactant concentrations on the velocity were investigated. The swimming microtube captured cyanine dye in the HSA component of the wall. Addition of an intermediate γ-Fe3 O4 layer allowed manipulation of the direction of movement of the tubule by using a magnetic field. Because the exterior surface is positively charged, the bubble-propelled microtubes adsorbed E. coli with high efficiency. The removal ratio of E. coli by a single treatment reached 99 %.
Keywords: bacteria; human serum albumin; layered compound; proteins; template synthesis.
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