Nickel nanowire swimmers for colloidal cargo transport near a solid surface

Rotating ferromagnetic nanowires (NWs) are capable of propulsion near a solid surface in fluid using a uniform rotating magnetic field. In this paper, we investigated the swimming behavior of a rotating nickel NW and a strategy to transport colloidal cargo. A rotating NW is assembled with one or two colloidal microparticles and is transported near a solid surface. The results show that the motions of the NW swimmers assembled with cargo can be precisely steered near a solid surface. Moreover, contrary to the transport mechanism based on direct translation of cargo in which the velocity of the nanowire is reduced due to the additional drag resistance from the cargo, the swimming velocity of the nickel NW swimmer assembled with dual particles at its two ends is significantly enhanced, indicating that tumbling motion, i.e. rotation plus translation, is a promising approach for NW propulsion and cargo transport near a solid surface. The results also imply that rotating 1-D ferromagnetic nanostructures are capable of rapid targeted delivery and are good candidates for manipulation of cellular and sub-cellular objects in an aqueous low Reynolds number environment.