title: Microfluidic chip-based nanoelectrode array as miniaturized biochemical sensing platform for prostate-specific antigen detection.
abstract: A microfluidic biosensor chip with an embedded three-electrode configuration is developed for the study of the voltammetric response of a nanoelectrode array with controlled inter-electrode distance in a nanoliter-scale sample volume. The on-chip three-electrode cell consists of a 5 × 5 array of Au working nanoelectrodes with radii between 60 and 120 nm, a Cl(2)-plasma-treated Ag/AgCl reference electrode, and a Au counter electrode. The nanoelectrode array is fabricated by creating high-aspect-ratio pores through an alumina insulating layer using an I(2) gas-assisted focused-ion-beam (FIB) milling, ion beam sculpting, and electrodeposition of Au. The glass substrate with the electrode pattern is assembled with a polydimethylsiloxane (PDMS) microchannel slab giving a volume of 180 nL for each channel. Cyclic voltammetry calibration with a standard redox species exhibits a significant increase of current density by two orders of magnitude compared to that obtained from a microelectrode. On-chip functionalization of the nanoelectrodes with a prostate-specific antigen (PSA) biosensor complex and detection of PSA based on a competitive immunoassay method are performed. The detection limit is approximately 10 pg/mL (∼270 fM), which corresponds to roughly 30,000 copies of PSA in the microchannel test volume.
authors.affiliation: Division of Engineering, Brown University, 182 Hope Street, Providence, RI 02912, USA.
authors.forename: Napat
authors.initials: N
authors.lastname: Triroj
authors.forename: Papot
authors.initials: P
authors.lastname: Jaroenapibal
authors.forename: Haibin
authors.initials: H
authors.lastname: Shi
authors.forename: Joanne I
authors.initials: JI
authors.lastname: Yeh
authors.forename: Roderic
authors.initials: R
authors.lastname: Beresford
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D001774:Blood Chemical Analysis / Q000295:instrumentation; D055664:Electrochemical Techniques; D004867:Equipment Design; D006046:Gold; D006801:Humans; D008297:Male; D053768:Metal Nanoparticles / Q000648:ultrastructure; D008839:Microelectrodes; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D008855:Microscopy, Electron, Scanning; D055616:Microtechnology; D049329:Nanostructures / Q000648:ultrastructure; D036103:Nanotechnology; D010084:Oxidation-Reduction; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis
chemical_list: D006046:Gold; D017430:Prostate-Specific Antigen