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

Area of Science:

• Electrochemistry
• Nanomaterials Science
• Biosensing

Background:

• Interdigitated electrodes (IDEs) offer electrochemical signal enhancement but suffer from high capacitance and oxygen reduction interference.
• Nanoporous gold (NPG) electrodes can reduce impedance but require further optimization for sensitive detection.

Purpose of the Study:

• To develop modified NPG electrodes that minimize background capacitance and oxygen interference for improved electrochemical detection.
• To demonstrate the utility of these modified electrodes for sensitive and selective detection of small molecules and biomolecular interactions.

Main Methods:

• Modification of NPG electrodes with alkanethiols to passivate against oxygen reduction and lower capacitance.
• Electrochemical characterization using cyclic voltammetry and electrochemical impedance spectroscopy.
• Application in a multiplexed sensor array for detecting peptide receptor binding to SARS-CoV-2 S-protein via a sandwich assay.

Main Results:

• Alkanethiol modification significantly lowered background capacitance and improved electron transfer rates (reduced ΔE and Rct) compared to planar gold electrodes.
• Achieved sensitive detection of pyocyanin, p-aminophenol, and selective dopamine detection in the presence of ascorbic acid.
• Demonstrated successful screening of peptide receptor binding to SARS-CoV-2 S-protein using the NPG array, validated against ELISA.

Conclusions:

• Alkanethiol-modified NPG electrodes provide a robust platform for sensitive and selective electrochemical biosensing.
• This approach is particularly valuable for small-volume, complex sample analysis where optical methods are limited.
• The multiplexed sensor arrays show promise for applications in diagnostics and drug discovery.