title: Fast immobilization of probe beads by dielectrophoresis-controlled adhesion in a versatile microfluidic platform for affinity assay.
abstract: The use of probe beads for lab-on-chip affinity assays is very interesting from a practical point of view. It is easier to handle and trap beads than molecules in microfluidic systems. We present a method for the immobilization of probe beads at defined areas on a chip using dielectrophoresis (DEP)-controlled adhesion. The method is fast, i.e., it takes between 10 and 120 s--depending on the protocol--to functionalize a chip surface at defined areas. The method is versatile, i.e., it works for beads with different types of probe molecule coatings. The immobilization is irreversible, i.e., the retained beads are able to withstand high flow velocities in a flow-through device even after the DEP voltage is turned off, thus allowing the use of conventional high-conductivity analyte buffers in the following assay procedure. We demonstrate the on-chip immobilization of fluorescent beads coated with biotin, protein A, and goat-antimouse immunoglobulin G (IgG). The number of immobilized beads at an electrode array can be determined from their fluorescence signal. Further, we use this method to demonstrate the detection of streptavidin and mouse IgG. Finally, we demonstrate the feasibility of the parallel detection of different analyte molecules on the same chip.
authors.affiliation: Centre Suisse d'Electronique et de Microtechnique, Alpnach, Switzerland. janko.auerswald@csem.ch
authors.forename: Janko
authors.initials: J
authors.lastname: Auerswald
authors.forename: David
authors.initials: D
authors.lastname: Widmer
authors.forename: Nico F
authors.initials: NF
authors.lastname: de Rooij
authors.forename: André
authors.initials: A
authors.lastname: Sigrist
authors.forename: Thomas
authors.initials: T
authors.lastname: Staubli
authors.forename: Thomas
authors.initials: T
authors.lastname: Stöckli
authors.forename: Helmut F
authors.initials: HF
authors.lastname: Knapp
mesh_terms: D000818:Animals; D001710:Biotin / Q000737:chemistry; D004586:Electrophoresis / Q000379:methods*; D007074:Immunoglobulin G / Q000032:analysis; D046210:Microfluidic Analytical Techniques; D008863:Microspheres; D015335:Molecular Probes / Q000737:chemistry*; D013205:Staphylococcal Protein A / Q000737:chemistry; D019809:Streptavidin / Q000032:analysis
chemical_list: D007074:Immunoglobulin G; D015335:Molecular Probes; D013205:Staphylococcal Protein A; D001710:Biotin; D019809:Streptavidin