title: Capacitive immunoaffinity biosensor based on vertically paired ring-electrodes.
abstract: A capacitive biosensor was developed by using a vertically paired ring-electrode for the non-labeled immunoassay. The vertically paired ring-electrode was prepared by sequential deposition and etching processes. Two electrodes were layered on glass substrate by sputtering of gold layers with thicknesses of 50 nm and 100 nm, and a parylene-C film with a thickness of 550 nm was positioned between the electrode layers as a dielectric material by thermal deposition. The top layer was made by spin coating of SU-8. And then, the ring-electrodes were exposed at the wall of the layered structure by sequential etching processes. The fabricated electrodes were characterized by cyclic voltammetry of a well-known redox couple of 3,3',5,5'-tetramethylbenzidine. The non-labeled detection of antigen-antibody interaction was demonstrated by using anti-horseradish peroxidase (HRP) antibodies and C-reactive protein (CRP) as model analytes. When the model analytes were bound to the vertically paired ring-electrode, the impedance change was measured during the immunoassay steps, and the measured impedance was analyzed by using a model circuit of the ring-electrode, and the capacitance was estimated to be dependent on the adsorption of analytes between the ring-electrodes.
authors.affiliation: Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-Ro, Seodaemun-Gu Seoul 120-749, Korea.
authors.forename: Ga-Yeon
authors.initials: GY
authors.lastname: Lee
authors.forename: Yong-Hwan
authors.initials: YH
authors.lastname: Choi
authors.forename: Ha-Wook
authors.initials: HW
authors.lastname: Chung
authors.forename: Hyuk
authors.initials: H
authors.lastname: Ko
authors.forename: Sungbo
authors.initials: S
authors.lastname: Cho
authors.forename: Jae-Chul
authors.initials: JC
authors.lastname: Pyun
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D003217:Conductometry / Q000295:instrumentation*; D025802:Electric Capacitance; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity