Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10429536 | Biosensors and Bioelectronics | 2011 | 7 Pages |
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 5Â ÃÂ 5 array of Au working nanoelectrodes with radii between 60 and 120Â nm, a Cl2-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 I2 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 180Â 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 10Â pg/mL (â¼270Â fM), which corresponds to roughly 30,000 copies of PSA in the microchannel test volume.
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Authors
Napat Triroj, Papot Jaroenapibal, Haibin Shi, Joanne I. Yeh, Roderic Beresford,