(J-386) A Highly Selective Microfluidic COVID Detection System Utilizing Electrical Impedance and Electrode Technology

Introduction:: The urgent need for quick, accurate, and focused diagnostic techniques to identify SARS-CoV-2 infection has been brought to light by the COVID-19 pandemic. Current detection methods, such as polymerase chain reaction (PCR) and antigen tests, have limitations in terms of scalability, turnaround time, and sensitivity, particularly in the early stages of infection or in cases of low viral loads. In this study, we describe a novel microfluidic electrochemical detection method for the SARS-CoV-2 virus that is based on the beneficial interaction of electrical impedance and cutting-edge electrode technology. Our method makes use of carbon electrodes that have had aryl diazonium grafted onto them. This creates a secure foundation for further functionalizing the electrode. The carboxyl groups on the electrode surface are then activated via EDC/NHS chemistry, allowing the immobilization of ACE2, the SARS-CoV-2 target receptor. Changes in impedance occur as a result of the SARS-CoV-2 samples' exposure to the electrode immobilized with ACE2. We are able to verify the successful grafting and immobilization of each layer and keep track of the impedance changes that are a reliable sign of layering by doing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) after each step. Our findings show that the suggested approach has great selectivity and sensitivity for SARS-CoV-2, opening the door to the creation of sophisticated electrochemical diagnostic instruments for quick, point-of-care diagnosis of COVID-19 and other viral illnesses.

Materials and Methods:: In this work, we built our detection system on a foundation of carbon electrodes. The carbon electrodes were modified using the aryl diazonium salt, and the carboxyl groups on the electrode surface were activated using EDC/NHS. The immobilization and detection procedures also made use of samples of SARS-CoV-2, ACE2 protein, and phosphate-buffered saline (PBS). PBS was used to dilute the ACE2 protein to a concentration of 1ug/mL and pH 7 DI water was used to dilute the virus into multiple dilution factors ranging from 2x to 1000x dilution. To graft a stable layer onto the working electrode, the carbon electrodes were cleaned initially using diluted sulfuric acid and treated with the aryl diazonium salt. The carboxyl groups were then activated on the modified electrode surface using EDC/NHS. ACE2 protein, which served as the target receptor for SARS-CoV-2 after activation, was immobilized on the electrode. SARS-CoV-2 samples were then put on the working electrode to test the system's capacity for detection. To guarantee correct grafting, immobilization, and stacking, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were made after each step. As a sign of successful layer development and interaction with the SARS-CoV-2 samples, the impedance variations were carefully observed. The sensitivity and selectivity of the suggested COVID detection system were evaluated using the data from all trials, which were all completed under carefully monitored settings.


Results, Conclusions, and Discussions:: As a result of the electrochemical impedance spectroscopy (EIS) findings, effective grafting, immobilization, and viral identification were confirmed at each stage of the experiment. Following the aryl diazonium grafting procedure, the impedance values were initially at their maximum, indicating the creation of a stable layer on the carbon electrode surface. Following ACE2 immobilization, the impedance values dropped, indicating that the target receptor had successfully attached. The contact with the SARS-CoV-2 virus produced the lowest impedance values, indicating successful virus identification. Additionally, our results showed that with less diluted samples compared to more diluted ones, the degree of separation between the ACE2-immobilized electrode and the virus increased. In particular, higher dilution factors (100x) were more successfully detected by the detection system than lower dilution factors (1000x). Based on this finding, it appears that the new detection method is more sensitive and effective at identifying SARS-CoV-2 in samples with higher viral quantities. These findings demonstrate the electrochemical detection system's efficiency in detecting SARS-CoV-2, as well as its potential for use in point-of-care diagnostics and aiding quick responses to COVID-19 and other viral epidemics.


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