Desenvolvimento de sensores amperométricos para detecção de imunoglobulinas contra a proteína Nucleocapsídica de SARS-CoV-2

Abstract

The pandemic situation of the early 20s caused by the new coronavirus disease (COVID-19) is one of the main infections that affected the world population and has become a current public health problem due to the high transmission rate. Thus, the importance and urgent need for simple, fast, and accurate diagnostic tests for the detection and screening of COVID-19 is highlighted. The present study aims to develop electrochemical immunosensors based on a methodology of electrode functionalization for fast, low cost and high sensitivity measurements of SARS-CoV-2 immunoglobulins. In the manufacture of immunosensors, screen-printed carbon electrodes (SPCE) were modified with carboxylated graphene (CG) and used as conducting support. The methodology of electrode functionalization was carried out through immobilization of the viral nucleocapsid protein (N-protein). The electrode modification stages were characterized by electrochemical techniques (cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS)). The detection step was performed by chronoamperometric method, using antibodies labeled with the horseradish peroxidase enzyme (anti-IgG-HRP e anti-IgA-HRP) and 3,3′,5,5′-tetramethylbenzidine (TMB) as redox substrate to generate current changes proportional to the concentration of nucleocapsid SARS-CoV-2 immunoglobulins. The recorded results showed higher current values in Samples with the presence of IgG-SARS-Cov-2 and IgA-SARS-CoV-2 detected with negative reflection, the evaluation of the ability of these immunosensors to detect infection by the new coronavirus was test on clinical samples of human serum, which revealed its ability to pick up positive patients from healthy (uninfected) individuals for SARS-CoV-2 based on the presence of IgG and IgA in human serum samples. The developed method present good sensibility (limit of detection of 0,0202% and 0,0624% for IgG-SARS-CoV-2 and IgG-SARS-CoV-2, respectively), and showed be selective and reproductible.