title: Target delivery in a microfluidic immunosensor.
abstract: A study is presented that examines the effect of microfluidic mixing elements on direct and sandwich assays performed in microchannels. Patterned grooves were embossed in the top of microchannels made in PDMS using soft lithography. The grooves redirected the fluid flowing in the channel, enhancing delivery of the target from the bulk fluid to the surface and preventing the formation of a depletion layer at the surface. Comparing assays in grooved and plain channels demonstrated that the mixers improved assay results by 26-46%. A computational flow analysis showed that the grooves caused virtual particles in the bulk flow to come close to the surface ( approximately 11 microm) which is consistent with the signal increase seen experimentally. Direct assays for several concentrations of CY5-labeled biotin were performed in the microchannels. The mixers also improved signal intensity in sandwich assays for botulinum toxin which required mixing of the reagents as well as the direction of the target to the surface.
authors.affiliation: Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC 20375, United States.
authors.forename: Joel P
authors.initials: JP
authors.lastname: Golden
authors.forename: Tamara M
authors.initials: TM
authors.lastname: Floyd-Smith
authors.forename: David R
authors.initials: DR
authors.lastname: Mott
authors.forename: Frances S
authors.initials: FS
authors.lastname: Ligler
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D001905:Botulinum Toxins / Q000032:analysis* / Q000276:immunology; D016503:Drug Delivery Systems / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D015200:Fluoroimmunoassay / Q000295:instrumentation* / Q000379:methods; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001905:Botulinum Toxins