title: Simple synthesis of functionalized superparamagnetic magnetite/silica core/shell nanoparticles and their application as magnetically separable high-performance biocatalysts.
abstract: Uniformly sized silica-coated magnetic nanoparticles (magnetite@silica) are synthesized in a simple one-pot process using reverse micelles as nanoreactors. The core diameter of the magnetic nanoparticles is easily controlled by adjusting the w value ([polar solvent]/[surfactant]) in the reverse-micelle solution, and the thickness of the silica shell is easily controlled by varying the amount of tetraethyl orthosilicate added after the synthesis of the magnetite cores. Several grams of monodisperse magnetite@silica nanoparticles can be synthesized without going through any size-selection process. When crosslinked enzyme molecules form clusters on the surfaces of the magnetite@silica nanoparticles, the resulting hybrid composites are magnetically separable, highly active, and stable under harsh shaking conditions for more than 15 days. Conversely, covalently attached enzymes on the surface of the magnetite@silica nanoparticles are deactivated under the same conditions.
authors.affiliation: National Creative Research Initiative Center for Oxide Nanocrystalline Materials and School of Chemical Engineering, Seoul National University, Seoul 151-744, Korea.
authors.forename: Jinwoo
authors.initials: J
authors.lastname: Lee
authors.forename: Youjin
authors.initials: Y
authors.lastname: Lee
authors.forename: Jong Kyu
authors.initials: JK
authors.lastname: Youn
authors.forename: Hyon Bin
authors.initials: HB
authors.lastname: Na
authors.forename: Taekyung
authors.initials: T
authors.lastname: Yu
authors.forename: Hwan
authors.initials: H
authors.lastname: Kim
authors.forename: Sang-Mok
authors.initials: SM
authors.lastname: Lee
authors.forename: Yoon-Mo
authors.initials: YM
authors.lastname: Koo
authors.forename: Ja Hun
authors.initials: JH
authors.lastname: Kwak
authors.forename: Hyun Gyu
authors.initials: HG
authors.lastname: Park
authors.forename: Ho Nam
authors.initials: HN
authors.lastname: Chang
authors.forename: Misun
authors.initials: M
authors.lastname: Hwang
authors.forename: Je-Geun
authors.initials: JG
authors.lastname: Park
authors.forename: Jungbae
authors.initials: J
authors.lastname: Kim
authors.forename: Taeghwan
authors.initials: T
authors.lastname: Hyeon
mesh_terms: D002384:Catalysis; D003432:Cross-Linking Reagents / Q000737:chemistry; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D008280:Magnetics; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D012822:Silicon Dioxide / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D003432:Cross-Linking Reagents; D004800:Enzymes, Immobilized; D012822:Silicon Dioxide