title: Formation and properties of magnetic chains for 100 nm nanoparticles used in separations of molecules and cells.
abstract: Optical observations of 100 nm metallic magnetic nanoparticles are used to study their magnetic field induced self assembly. Chains with lengths of tens of microns are observed to form within minutes at nanoparticle concentrations of 10(10) per mL. Chain rotation and magnetophoresis are readily observed, and SEM reveals that long chains are not simple single particle filaments. Similar chains are detected for several 100 nm commercial bio-separation nanoparticles. We demonstrate the staged magnetic condensation of different types of nanoparticles into composite structures and show that magnetic chains bind to immunomagnetically labeled cells, serving as temporary handles which allow novel magnetic cell manipulations.
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wilson
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.forename: Cheryl Wong Po
authors.initials: CW
authors.lastname: Fu
authors.forename: Ai Leen
authors.initials: AL
authors.lastname: Koh
authors.forename: Richard S
authors.initials: RS
authors.lastname: Gaster
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Earhart
authors.forename: Aihua
authors.initials: A
authors.lastname: Fu
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Heilshorn
authors.forename: Robert
authors.initials: R
authors.lastname: Sinclair
authors.forename: Shan X
authors.initials: SX
authors.lastname: Wang