title: Cargo-towing fuel-free magnetic nanoswimmers for targeted drug delivery.
abstract: Fuel-free nanomotors are essential for future in-vivo biomedical transport and drug-delivery applications. Herein, the first example of directed delivery of drug-loaded magnetic polymeric particles using magnetically driven flexible nanoswimmers is described. It is demonstrated that flexible magnetic nickel-silver nanoswimmers (5-6 μm in length and 200 nm in diameter) are able to transport micrometer particles at high speeds of more than 10 μm s(-1)  (more than 0.2 body lengths per revolution in dimensionless speed). The fundamental mechanism of the cargo-towing ability of these magnetic (fuel-free) nanowire motors is modelled, and the hydrodynamic features of these cargo-loaded motors discussed. The effect of the cargo size on swimming performance is evaluated experimentally and compared to a theoretical model, emphasizing the interplay between hydrodynamic drag forces and boundary actuation. The latter leads to an unusual increase of the propulsion speed at an intermediate particle size. Potential applications of these cargo-towing nanoswimmers are demonstrated by using the directed delivery of drug-loaded microparticles to HeLa cancer cells in biological media. Transport of the drug carriers through a microchannel from the pick-up zone to the release microwell is further illustrated. It is expected that magnetically driven nanoswimmers will provide a new approach for the rapid delivery of target-specific drug carriers to predetermined destinations.
authors.affiliation: Department of Nanoengineering, University of California, San Diego, La Jolla, CA 92093-0448, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Gao
authors.forename: Daniel
authors.initials: D
authors.lastname: Kagan
authors.forename: On Shun
authors.initials: OS
authors.lastname: Pak
authors.forename: Corbin
authors.initials: C
authors.lastname: Clawson
authors.forename: Susana
authors.initials: S
authors.lastname: Campuzano
authors.forename: Erdembileg
authors.initials: E
authors.lastname: Chuluun-Erdene
authors.forename: Erik
authors.initials: E
authors.lastname: Shipton
authors.forename: Eric E
authors.initials: EE
authors.lastname: Fullerton
authors.forename: Liangfang
authors.initials: L
authors.lastname: Zhang
authors.forename: Eric
authors.initials: E
authors.lastname: Lauga
authors.forename: Joseph
authors.initials: J
authors.lastname: Wang
mesh_terms: D004317:Doxorubicin / Q000494:pharmacology; D016503:Drug Delivery Systems / Q000379:methods*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D019344:Lactic Acid / Q000737:chemistry; D008280:Magnetics; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D059008:Time-Lapse Imaging
chemical_list: D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D004317:Doxorubicin