OPERATION OF AN ELECTROCHEMICAL BIOSENSOR DEVELOPED FOR COVID-19 DETECTIONIN SARS-COV-2 FREE AND INFECTED HUMAN SALIVA

Abstract: The demand for the improvement of currently available tests for qualitative non-invasive diagnostic of COVID-19, i.e., the development of new methods for fast, low-cost and accurate tests for the conformation of SARS-CoV-2, is increasing rapidly. Among many different approaches, electrochemical biosensors, which have the capability of miniaturization and could be available globally in most remote areas, may also help in avoiding the transmission of COVID-19 disease. When properly designed, electrochemical tests might have higher sensitivity, specificity, and accuracy, which is very important for COVID-19 diagnostics. In this work a saliva based electrochemical biosensor developed for COVID-19 detection was tested using real human samples. First, 41 saliva samples from volunteers were collected during January-February 2022, when the rate of SARS-CoV-2 infection was the highest in Skåne region, Sweden. Second, cyclic voltammograms of SARS-CoV-2 biomodified electrodes were recorded in buffers with and without SARS-CoV-2 positive control, as well as in saliva samples. Third, the samples were analyzed using commercially available COVID-19 salivary tests, viz., rapid antigen test and RT-qPCR (quantitative reverse transcription polymerase chain reaction). It was shown that 8 samples were collected from COVID-19 positive volunteers. Based on the analysis of all experimental results it was concluded that compared to rapid antigen and RT-qPCR tests, the sensitivity and reproducibility of the biosensor is not enough for real practical applications. Thus, some suggestions for further improvement of basic parameters of the developed biodevice were made.