Redox cycling-based signal amplification at alkanethiol modified nanoporous gold interdigitated microelectrodes

• Published in: Analytica chimica acta Vol. 1316; p. 342818
• Main Authors: Liu, Yi, Arjun, Ajith Mohan, Webb, Sean, Wolfe, Monica, Chávez, Jorge L., Swami, Nathan S.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 08-08-2024
• Subjects: Aminophenols - chemistry; Biosensing Techniques; Dopamine - analysis; Dopamine - chemistry; Electrochemical Techniques - instrumentation; Gold - chemistry; Humans; Interdigitated electrodes; Limit of Detection; Microelectrodes; Nanopores; Nanoporous gold; Oxidation-Reduction; Peptide screening; Redox amplification; SARS COV2 S-Protein; SARS-CoV-2 - isolation & purification; Sulfhydryl Compounds - chemistry; Peptide screening; Nanoporous gold; Redox amplification; Interdigitated electrodes; SARS COV2 S-Protein
• ISSN: 0003-2670; 1873-4324; 1873-4324
• DOI: 10.1016/j.aca.2024.342818

Interdigitated electrodes (IDEs) enable electrochemical signal enhancement through repeated reduction and oxidation of the analyte molecule. Porosity on these electrodes is often used to lower the impedance background. However, their high capacitive current and signal interferences with oxygen reduction limit electrochemical detection ability. We present utilization of alkanethiol modification on nanoporous gold (NPG) electrodes to lower their background capacitance and chemically passivate them from interferences due to oxygen reduction, while maintaining their fast electron transfer rates, as validated by lower separation between anodic and cathodic peaks (ΔE) and lower charge transfer resistance (Rct) values in comparison to planar gold electrodes. Redox amplification based on this modification enables sensitive detection of various small molecules, including pyocyanin, p-aminophenol, and selective detection of dopamine in the presence of ascorbic acid. Alkanethiol NPG arrays are applied as a multiplexed sensor testbed within a well plate to screen binding of various peptide receptors to the SARS COV2 S-protein by using a sandwich assay for conversion of PAPP (4-aminophenyl phosphate) to PAP (p-aminophenol), by the action of AP (alkaline phosphatase), which is validated against optical ELISA screens of the peptides. Such arrays are especially of interest in small volume analytical settings with complex samples, wherein optical methods are unsuitable.
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•Nanoporous interdigitated microelectrodes for redox amplification-based detection.•Electrode modification with monolayers retains high electron transfer kinetics.•Electrode modification with monolayers reduces signal interference from oxygen reduction.•Electrode modification for selective detection of dopamine in the presence of ascorbic acid.•Redox amplification for screening of peptide receptors to the SARS COV2 S-protein.