title: Flow sandwich-type immunoassay in microfluidic devices based on negative dielectrophoresis.
abstract: Microparticles have been manipulated in a microfluidic channel by means of negative dielectrophoresis (n-DEP), and the approach applied to a heterogeneous immunoassay system. A microfluidic device, with three-dimensional (3-D) microelectrodes fabricated on two substrates, was used to manipulate particle flow in the channel and to capture the particles in the caged area that was enclosed by the collector electrodes. Polystyrene microparticles (6 microm diameters) modified with anti-mouse immunoglobulin G (IgG) were manipulated and captured in the caged area when surrounded by intense n-DEP electric fields. Specifically, particles were trapped when AC voltages with amplitudes of 6-15 V(peak) and frequencies over 500 kHz were applied to the two facing microelectrodes. A heterogeneous sandwich immunoassay was achieved by successively injecting a sample solution containing mouse antigen (IgG), and a solution containing a secondary antibody with a signal source (FITC-labeled anti-mouse IgG antibody), into the channel. The fluorescence intensity from captured particles in the caged area increased with increasing concentrations (10 ng/ml to 10 microg/ml) of mouse IgG. The described system enables mouse IgG to be assayed in 40 min. Thus, the automatic separation of free fractions from desired analytes and labeled antibodies can be achieved using a microfluidic device based on n-DEP.
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, 6-6-11 Aoba, Aramaki, Aoba, Sendai 980-8579, Japan. yasu@bioinfo.che.tohoku.ac.jp <yasu@bioinfo.che.tohoku.ac.jp>
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yasukawa
authors.forename: Masato
authors.initials: M
authors.lastname: Suzuki
authors.forename: Takashi
authors.initials: T
authors.lastname: Sekiya
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shiku
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Matsue
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D046209:Electrophoresis, Microchip / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017022:Flow Injection Analysis / Q000295:instrumentation* / Q000379:methods; D015200:Fluoroimmunoassay / Q000295:instrumentation* / Q000379:methods; D007074:Immunoglobulin G / Q000032:analysis* / Q000276:immunology; D008839:Microelectrodes; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D007074:Immunoglobulin G