Selective decorating Ag and MnOx nanoparticles on halloysite and used as micromotor for bacterial killing

Threats of bacterial infection represent one of the most persistent issues of public health, and efficient bacteria killing materials are to be developed. Taking inspirations from nature, a new class of halloysite (Hal)-based bacteria killing materials (MnOx-Ag/Hal) that were able to self-move in aqueous solution was prepared. The asymmetric halloysite tubes are used as substrates. Silver (Ag) nanoparticles are loaded both in the lumen and on the external surface, and manganese oxide (MnOx) was distributed on the outside walls. Fuel with low concentration of H2O2, the catalyst Ag and MnOx would decompose H2O2 into gas bubbles (O-2), and the back-thrust bubbles provided forward forces for jet movement, which improved the antibacterial efficiency. The fabricated MnOx-Ag/Hal exhibited powerful self-propelled motion with velocity of 18 +/- 4 mu m/s achieved at 0.2 wt% H2O2. The MnOx-Ag/Hal generated Ag+ ions and highly reactive oxygen species that could efficiently kill E. coli. By coupling the antibacterial capabilities of H2O2, Ag and highly reactive oxygen species with powerful self propulsion, the prepared micromotors were capable of killing 97% of E. coli within 2.0 min, which was threefold as the counterpart of MnOx-Ag/Hal in the absence of H2O2 that cannot move efficiently. The biocompatible micromotors offered an encouraging strategy for rapid bacteria killing in clinical and environment fields.