title: Simultaneous sample washing and concentration using a "trapping-and-releasing" mechanism of magnetic beads on a microfluidic chip.
abstract: Simultaneous washing and concentration of functionalized magnetic beads in a complex sample solution were demonstrated by applying a rotational magnetic actuation system to a microfluidic chip under continuous flow conditions. The rotation of periodically arranged small permanent magnets close to the fluidic channel carrying a magnetic bead suspension allows trapping and releasing of the beads along the fluidic channel in a periodical manner. Each trapping and releasing event resembles one washing cycle. A purification efficiency of magnetic beads out of a mixed magnetic and non-magnetic bead sample solution of 83±4% at a flow rate of 0.5 µL min(-1), and a magnetic bead recovery or concentration efficiency of 91±5% were achieved using a flow rate of 0.2 µL min(-1). The detection performance of the device was experimentally evaluated with two different bioassays, using either streptavidin-coated magnetic beads in combination with biotinylated fluorescent isothiocyanate (FITC), or a mouse antigen (Ag)-antibody (Ab) system.
authors.affiliation: Laboratory of Microsystems, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland. qasem.alramadan@epfl.ch
authors.forename: Qasem
authors.initials: Q
authors.lastname: Ramadan
authors.forename: Martin A M
authors.initials: MA
authors.lastname: Gijs
mesh_terms: D000818:Animals; D000937:Antigen-Antibody Reactions; D019921:Biotinylation; D004867:Equipment Design; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D008280:Magnetics; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D008856:Microscopy, Fluorescence; D008863:Microspheres; D019904:Polymethyl Methacrylate / Q000737:chemistry; D019809:Streptavidin / Q000737:chemistry
chemical_list: D019904:Polymethyl Methacrylate; D019809:Streptavidin; D016650:Fluorescein-5-isothiocyanate