Electrochemical Detection of S-RBD Protein for Point-of-Care SARS-CoV-2 Monitoring Using Platinum-Black-Based Sensor Array

The COVID-19 pandemic has led to a substantial increase in the advancement of point-of-care (POC) diagnostic tools due to their potential utility in detecting and managing the spread of the disease. Currently, many diagnostic techniques necessitate advanced laboratory equipment and specialized expertise to deliver dependable, cost-effective, specific, and sensitive POC tests for COVID-19 diagnosis. Herein, we report a highly sensitive electrochemical sensor array that features S-RBD protein, covalently anchored on the surface-engineered Pt-black-coated microdisk gold electrodes to monitor severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Computer simulations were performed using different electrode gaps to optimize and fabricate the gold microdisk electrode array. The high sensitivity was ensured by decreasing the electrode gap as well as by depositing Pt-black nanoparticles on the microdisk gold electrodes, by means of chronopotentiometry. The electrical readout depends on monitoring changes in the cyclic voltammograms at the electrode/electrolyte interface as a result of the competitive interaction between monoclonal COVID-19 antibodies and varying antigen concentrations. Overall, the developed electrochemical sensor array exhibits promising electroanalytical capabilities by displaying an excellent linear response ranging from 100 to 1 µg/ml with a detection limit of ~ (0.23 ng/ml). In addition, as a proof-of-concept application, the developed electrochemical sensor array was employed as a sensing platform for the detection of heat-inactivated SARS-CoV-2. Such accomplishments highlight the advantages of low-cost localized electronic devices with high sensitivity and rapid multiple samples detection capabilities to play a crucial role in controlling the spread of infectious diseases like COVID-19.