Nanofluidic Redox Cycling Amplification for the Selective Detection of Catechol

Abstract

We have developed a chip-based nanofluidic device to amplify the electrochemical signal of catechols by orders of magnitude. The amplification is based on rapid redox cycling between plane parallel electrodes inside a nanochannel. We show that it is possible to monitor the signal of only a few hundred molecules residing in the active area of the nanofluidic sensor. Furthermore, due to the nanochannel design, the sensor is immune to interference by molecules undergoing irreversible redox reactions. We demonstrate the selectivity of the device by detecting catechol in the presence of ascorbic acid, whose oxidized form is only stable for a short time. The interference of ascorbic acid is usually a challenge in the detection of catecholamines in biological samples.

Redox cycling in nanofluidic channels using interdigitated electrodes

“…A clear wave is observed in redox cycling mode, whereas the corresponding wave in one-electrode mode is well-defined but small compared to the background signal. The redox cycling voltammogram also exhibits hysteresis, suggesting that potential-dependent adsorption is occurring [46]. These results correspond to an amplification factor of ∼110, illustrating the effectiveness of redox cycling amplification inside of a nanochannel device.…”

“…These results correspond to an amplification factor of ∼110, illustrating the effectiveness of redox cycling amplification inside of a nanochannel device. This value is larger than the highest amplification values reported for uncovered IDEs (A≈70) [45] but, as expected, is drastically lower than nF-TLCs, which confine the sample within a 55 nm channel (A≈10 4 ) [40,46,47]. Next, we compared the maximum current achieved in our devices to the finite element model.…”

“…Microfabrication techniques also offer an opportunity to construct thin-layer cells (TLCs) in which the electrode spacing is below 100 nm [40,46,47]. We refer to these here as nanofluidic TLCs (nF-TLCs).…”

“…Wolfrum et al recently demonstrated selective detection of catechol in the presence of ascorbic acid using nF-TLCs [46]. Since ascorbic acid decomposes quickly after being oxidized, it does not contribute significantly to the cycling current.…”

Tyrosinase Modified Poly(thionine) Electrodeposited Glassy Carbon Electrode for Amperometric Determination of Catechol

“…There are also literatures reported the similar mechanism by using nanofluidic devices. 35,36 This kind of device is also based on the redox cycling amplification between catechol and hydroquinone.…”