title: Fabrication of comb interdigitated electrodes array (IDA) for a microbead-based electrochemical assay system.
abstract: This research is directed towards developing a more sensitive and rapid electrochemical sensor for enzyme labeled immunoassays by coupling redox cycling at interdigitated electrode arrays (IDA) with the enzyme label beta-galactosidase. Coplanar and comb IDA electrodes with a 2.4 microm gap were fabricated and their redox cycling currents were measured. ANSYS was used to model steady state currents for electrodes with different geometries. Comb IDA electrodes enhanced the signal about three times more than the coplanar IDAs, which agreed with the results of the simulation. Magnetic microbead-based enzyme assay, as a typical example of biochemical detection, was done using the comb and coplanar IDAs. The enzymes could be placed close to the sensing electrodes (approximately 10 microm for the comb IDAs) and detection took less than 1 min with a limit of detection of 70 amol of beta-galactosidase. We conclude that faster and more sensitive assays can be achieved with the comb IDA.
authors.affiliation: Georgia Institute of Technology, Bioengineering Program, School of Mechanical Engineering, Atlanta, GA 30332, USA.
authors.forename: Sang Kyung
authors.initials: SK
authors.lastname: Kim
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hesketh
authors.forename: Changming
authors.initials: C
authors.lastname: Li
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Thomas
authors.forename: H Brian
authors.initials: HB
authors.lastname: Halsall
authors.forename: William R
authors.initials: WR
authors.lastname: Heineman
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D003198:Computer Simulation; D017076:Computer-Aided Design; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation* / Q000379:methods; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D018189:Immunomagnetic Separation / Q000295:instrumentation / Q000379:methods; D008839:Microelectrodes; D008863:Microspheres; D008956:Models, Chemical; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D001616:beta-Galactosidase / Q000032:analysis* / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D001616:beta-Galactosidase