Standalone Electrochemical Sensing of SARS-CoV-2: Unraveling the Mechanism

A. Ramanujam, G.G. Botte
Texas Tech University,
United States

Keywords: electrochemical SARS-CoV-2 Detection, COVID-19 Diagnosis, Biosensor


COVID-19 has prevailed for the past two years even with massive vaccination initiatives. A reason for this has been the ability of the SARS-CoV-2 virus to adapt itself and stay viable for longer durations than other corona viruses such as SARS-CoV, MERS-CoV, or Human CoV. Several diagnostic tests have leaped to detect SARS-CoV-2 much faster requiring fewer resources as compared to the gold standard reverse transcription polymerase chain reaction (RT-PCR). But they compromise on the sensitivity and specificity to achieve results rapidly and be portable to provide results at the point of use. This has led to a large number of false positives and false negatives which take a hit on the sensor accuracy. To overcome this drawback, it is highly important to understand how these rapid antigen tests work and what their underlying mechanism is. For this purpose, we try to understand the underlying mechanism of our Ultra-fast COVID-19 Diagnostic Sensor (UFC-19), a standalone electrochemical sensor that senses the SARS-CoV-2 viral proteins in samples using a locally formed electrocatalyst within milliseconds and provides a qualitative result within minutes of providing the sample. UFC-19 is a great tool for rapid screening and continuous monitoring of SARS-CoV-2 in saliva, water, or air. The sensor is specific to detecting corona viruses and can differentiate their signals against other viruses like HIV, Influenza and bacteria like E. coli. Our preliminary results indicate a very quick interaction (~1 ms) between the electrocatalyst and hydrogen occupancies of corona virus spike proteins occurring at the electrical double layer. Moreover, results also indicate that the current signals obtained from the different corona viruses vary in intensity and this variation is strongly correlated to the dissociation constants of these different corona viruses to human surfaces. According to the response of UFC-19, SARS-CoV-2 has the highest affinity (lowest dissociation) towards the electrocatalyst followed by MERS-CoV, SARS-CoV and least affinity towards human CoV in our analysis window. This difference in affinity to the sensor provides a plausible pathway to reliably distinguish different corona viruses and provide results that are highly specific and sensitive. These results also open the doors for using a similar approach to differentiate the different variants of SARS-CoV-2 and understand their infectious nature using UFC-19.