Fabrication of Template-Less Self-Propelled Micromotors Based on A Metal-Sandwiched Polytryptophan Body: An Experimental and DFT Study.

The diverse capabilities of self-propelled micro/nanomotors open up significant opportunities for various environmental and biomedical applications. Here, a synchronized two-lobed bubble exhaust drives micromotor comprising a metal (cobalt and gold) sandwiched polytryptophan body (Au/poly-Trp/Co) in a non-curved direction. The autonomous motion is achieved through the decomposition of chemical fuel to result in a kayak-like system. The ejected oxygen bubbles from the interfacial cobalt/polytryptophan layer, as well as the inert nature of the metal segments (Au-Co), were considered for some computational studies of the electronic properties of the composite and physical phenomena at the kayak/electrolyte interfaces, and confirmed the role of Co-Trp in the fuel decomposition. It is believed that the autonomous motion is the combined result of bubble recoil force, self-electrophoresis, and perturbation in the interfacial hydrogen-bond network of the poly-Trp body and water molecules. The velocity of the micromotor in the range 23±4 to 157±17 µm s-1 at different concentrations of H2 O2 from 1 % to 10 %. Depending on the method of fragmentation, it is possible to have both single and multiple motorized kayaks with lengths of 1.5 and 6 µm, respectively, that can be tailored for environmental applications.