title: Magnetically assisted and accelerated self-assembly of strawberry-like nano/microparticles.
abstract: Precisely controlling multiple components of functional materials with well-defined shapes and dimensions on the micro/nanometer scale promises to provide new electronic, magnetic, mechanical, and optical properties for novel sensors, circuits, and other materials application. Here for the first time we introduce a novel method to reliably pattern strawberry-like microspheres by employing magnetically directed and accelerated self-assembly of nano/microparticles in aqueous solution, without the use of a template (such as molds or grooves). The results show that 100-1000 nm paramagnetic "decorating particles" rapidly self-assembled onto the surface of fluorescent 4-5 mum spherical magnetized "core particles", producing strawberry-like particles with stable and precisely arranged microstructures. Magnetic CrO2 nanorods, approximately 60 nm in diameter and 300 nm long, attached to the nonplanar surface of the 4-5 microm polystyrene core microspheres, serve as nanometer magnetic traps, so as to attract and confine paramagnetic decorating particles. The ease and speed, with which these particles can be fabricated with the aid of magnetic force, and the flexibility to tailor their chemical and physical properties through the choice of decorating particles, should facilitate their use for practical application in materials science, biology, and technology.
authors.affiliation: Department of Chemistry, University of Michigan, 930 North University, Ann Arbor, Michigan 48109-1055, USA.
authors.forename: Hongmei
authors.initials: H
authors.lastname: Huang
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Anker
authors.forename: Kemin
authors.initials: K
authors.lastname: Wang
authors.forename: Raoul
authors.initials: R
authors.lastname: Kopelman
mesh_terms: D000465:Algorithms; D001360:Avidin / Q000737:chemistry; D001710:Biotin / Q000737:chemistry; D017608:Chromium Compounds / Q000737:chemistry; D008280:Magnetics; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D008863:Microspheres; D053758:Nanoparticles / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry; D010078:Oxazines / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D019809:Streptavidin / Q000737:chemistry
chemical_list: D017608:Chromium Compounds; D010078:Oxazines; D011137:Polystyrenes; D001360:Avidin; D001710:Biotin; D012822:Silicon Dioxide; D019809:Streptavidin; C044808:nile red; C023600:chromic oxide