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Reference electrode-free electrochemical detection using a bare interdigitated array electrode and initial counterbalancing O2 reduction
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DOI：10.1016/j.snb.2025.137909.png)
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Abstract
En 中文
In this study, we introduce a reference electrode-free two-electrode system that utilizes the electrochemical reduction of naturally dissolved O2 in aqueous solutions to counterbalance the oxidation of 4-aminophenol (AP) at an Au interdigitated array electrode. This system minimizes the potential variation at the working electrode and eliminates the need for a large potential difference between the two electrodes. The oxidation of AP produces 4-quinoneimine, inducing electrochemical-electrochemical (EE) redox cycling. Operating in phosphate-buffered saline (pH 7.4) ensures a low anodic background current within a potential range where AP (formal potential = 0.07 V vs. Ag/AgCl (3 M NaCl)) undergoes oxidation. Concurrently, the reduction of O2 occurs effectively near 0.1 V vs. Ag/AgCl. This setup enables the application of a small potential difference (0.3 V) to simultaneously achieve AP oxidation and O2 reduction, followed by efficient EE redox cycling. Unwanted side reactions involving O2 and H2O2 are minimal and do not interfere with the redox cycling. We applied this system to detect proteases (3CL protease from coronavirus SARS-CoV-2 and aminopeptidase N) that catalyze the release of AP from electro-inactive AP-conjugated peptides. Our approach demonstrates the potential for efficient EE redox cycling without requiring a reference electrode and added redox species.
Keywords:
Reference electrode
Two-electrode system
O 2 reduction
Au interdigitated array
Protease detection
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