The recent discovery of fuel-free propulsion of nanomotors using acoustic energy has provided a new avenue for using nanomotors in biocompatible media. Crucial to the application of nanomotors in biosensing and biomedical applications is the ability to remotely control and steer them towards targets of interest such as specific cells and tissues. We demonstrate in vitro magnetic steering of acoustically powered nanorod motors in a biologically compatible environment. Steering was accomplished by incorporating (40 ± 5) nm thick nickel stripes into the electrochemically grown nanowires. An external magnetic field of 15 mT to 40 mT was used to orient the motors, which were acoustically propelled along their long axes. In the absence of a magnetic field, (300 ± 30) nm diameter, (4.3 ± 0.2) µm long nanowires with (40 ± 5) nm thick magnetic stripes exhibit the same self-acoustophoretic behavior, including pattern formation into concentric nanowire circles, aligned spinning chains and autonomous axial motion, as their non-magnetic counterparts. In a magnetic field these wires and their paths are oriented as evidenced by their comparatively linear trajectories. Coordinated motion of multiple motors and targeting of individual motors towards HeLa cells with micron-level precision was demonstrated.
Pub Type: Journals
nanomotor, acoustofluidics, nanowire