Redox Cycling on Unmodified Gold Interdigitated Ultramicroelectrode Arrays for Interferent Free Electrochemical Detection of Pyocyanin

Pyocyanin (PYO) is a quorum-sensing signalling molecule that is secreted exclusively by Pseudomonas aeruginosa (P. aeruginosa). The monitoring of pyocyanin concentrations can therefore be used to readily detect the presence of P. aeruginosa Dissolved oxygen interference has hampered the use of materials for sensors, such as gold, for pyocyanin detection, unless degassing of samples is incorporated, limiting point of care applicability. To this end, carbon-based electrodes are typically employed but are limited in terms of reproducibility and miniaturisation. In this work we report oxygen interference free electrochemical detection of pyocyanin using an unmodified gold interdigitated array. Through the use of redox cycling, dissolved oxygen interference was minimised, and highly sensitive detection was achieved in both buffered conditions (73.4 nM) and real-world samples (100nM). Additionally, multiple strains of P. aeruginosa were investigated and the sensor was found to be highly accurate for all three strains (PA17, PA40, PA41) and demonstrated good agreement with the typical UV-Vis detection method employed. This approach demonstrates the potential for future point of care testing for pyocyanin, and thereby P. aeruginosa, using these sensors, without the need for sample modification.