Electrochemical Study of N-Acetyl Neuraminic Acid at Gold-Modified Screen-Printed Carbon Electrodes for Glycoprotein Sensor of SARS-CoV-2

Abstract An electrochemical sensor of SARS-CoV-2 spike glycoprotein S1 has been developed using N-acetyl neuraminic acid (Neu5Ac) as the biosensing agent based on the interaction between Neu5Ac with the N-terminal domain of spike glycoprotein S1. Gold-modified screen-printed carbon electrode (Au-SPCE), prepared by electrochemical deposition of gold particles on the screen-printed carbon electrode surface, was used to detect the presence of the SARS-CoV-2 from the change of electrochemical behavior of Neu5Ac. Cyclic voltammetry of Neu5Ac in phosphate buffer solution pH 7.6 at Au-SPCE electrodes observes a couple of oxidation and reduction peaks at the potentials of +0.6 and 0.1 V (vs. Ag/AgCl), respectively. The currents of both peaks linearly increased with the NAeu5Ac concentrations in the range from 0 to 200 µM. The sensitivity of 0.77 mA/mM and 0.47 mA/mM for reduction and oxidation currents were observed, respectively, with the estimated detection limits (LODs) of 51.05 µM and 35.77 µM. In the presence of SARS-CoV-2 spike glycoprotein S1 these current peaks decreased. At an optimum contact time of 30 min, a linear correlation to the current changes of the reduction peaks was observed in the spike glycoprotein S1 with the concentration ranges from 0 to 0.01 µg/ml. The estimated LOD of 0.7 ng/ml could be achieved with excellent stability (2.18% RSD value for n = 10), indicating the developed sensor is promising to be utilized in real applications of SARS-CoV-2 spike glycoprotein S1 detection.