title: Steering acoustically propelled nanowire motors toward cells in a biologically compatible environment using magnetic fields.
abstract: 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 toward 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 40-45 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 relatively linear trajectories. Coordinated motion of multiple motors and targeting of individual motors toward HeLa cells with micrometer-level precision was demonstrated.
authors.affiliation: Department of Chemistry, ‡Department of Physics, §Department of Biochemistry and Molecular Biology, ∥Department of Engineering Science and Mechanics, and ⊥Department of Cell and Developmental Biology Graduate Program, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Ahmed
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Lamar O
authors.initials: LO
authors.lastname: Mair
authors.forename: Robert D
authors.initials: RD
authors.lastname: Fraleigh
authors.forename: Sixing
authors.initials: S
authors.lastname: Li
authors.forename: Luz Angelica
authors.initials: LA
authors.lastname: Castro
authors.forename: Mauricio
authors.initials: M
authors.lastname: Hoyos
authors.forename: Tony Jun
authors.initials: TJ
authors.lastname: Huang
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Mallouk
mesh_terms: D000162:Acoustics; D006046:Gold / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D060526:Magnetic Fields; D008855:Microscopy, Electron, Scanning; D020409:Molecular Motor Proteins; D036103:Nanotechnology; D053770:Nanowires / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry
chemical_list: D020409:Molecular Motor Proteins; D006046:Gold; D012428:Ruthenium