Nanoband electrode for high‐performance in‐channel amperometric detection in dual‐channel microchip capillary electrophoresis

Abstract

A nanoband electrode detector integrated with a dual-channel polydimethylsiloxane microchip is proposed for in-channel amperometric detection in microchip capillary electrophoresis. Gold nanoband electrodes, which were fabricated on SU-8 substrates with a 100-nm-width gold layer, were introduced into the dual-channel microchip to be an electrochemical detector. Due to the nano-sized width of the detector, the noise of the amperometric detection was significantly reduced, and a high separation resolution was achieved for monitoring the analytes. The detection sensitivity of the system was improved by high signal-to-noise ratio, and a low detection limit on microchip was obtained for p-aminophenol (2.09 nM). Because of the high resolution in measuring half-peak width, the plate number that is used to evaluate the separation efficiency was 1.5-fold higher than that using 50-μm-width electrochemical detector. The effect of sample injection time and data acquisition time on separation efficiency was investigated, and an attractive separation efficiency was achieved with a plate number up to 17,500.

Advanced electroanalytical chemistry at nanoelectrodes

“…First, the nanoband electrode (Fig. 1A) 20 and electrode array were made by using bottom-up manufacturing technologies including photolithography, electron beam lithography (EBL) and focused ion beam (FIB) fabrication, 21 in which a metal layer was deposited on the top, bottom or sandwiched in-between the substrates. These methods could provide arrays or ensembles of nanoelectrodes.…”

Evaluation of in‐channel amperometric detection using a dual‐channel microchip electrophoresis device and a two‐electrode potentiostat for reverse polarity separations

“…No system peaks were reported in the original studies using the dual‐channel approach for normal polarity separations . However, we have observed system peaks when the electrodes were placed deep inside the channel under reverse polarity conditions with both the single‐channel and dual‐channel configurations with the two‐electrode potentiostat.…”

“…However, placing the electrode in the channel can lead to increased noise and shifts in the apparent redox potential for the analytes of interest . Chen and Hahn described a dual‐channel design with unique sample and reference channels to minimize noise due to the high voltage used for separation . They employed positive polarity and an isolated potentiostat in a three‐electrode configuration.…”

“…This configuration maintains the high efficiency separation advantage of in‐channel detection while also providing lower LOD. The Hahn group has employed this dual‐channel design for the determination of catecholamines and aminophenols , and has reported LOD in the low nanomolar range using normal polarity separation conditions.…”

A review of microdialysis coupled to microchip electrophoresis for monitoring biological events

“…Many groups are experimenting with nanoelectrodes [125], multiple electrodes [126-128], and 3D electrodes [104] to enhance selectivity and/or sensitivity. In the future, these increases in sensitivity and selectivity will permit better detection of biologically relevant molecules in MD-ME-EC.…”