Desenvolvimento de imunossensor eletroquímico para detecção de sars-cov-2

Abstract

SARS-CoV-2, belonging to the coronavirus family, consists of a positive-segment RNA virus, viruses that have spicules in their structure that have given them the name “corona”. SARS-CoV-2 is the third species of betacoronavirus to cause outbreaks in recent decades, and the first of these to cause a high number of infections and deaths resulting from the effects of the disease around the world, receiving pandemic status. The coronavirus has a high degree of transmissibility, requiring measures that are able to stop the spread. Current tests for COVID-19 consist of molecular tests and serological tests, which have disadvantages due to their high cost and delay. In this work, the fabrication of electrochemical immunosensor for the detection of SARS-CoV-2 antibodies is proposed. Immobilization of the antigen (N-protein) was performed on a carbon substrate modified with carboxylated graphene (CG). The construction steps were characterized by electrochemical techniques (cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), thermogravimetric analysis (TGA), , ATR-FTIR and XRD. Analytical detection was performed indirectly through the chronoamperometry technique, using antibody labeled with the enzyme HRP (IgG-HRP), and TMB in the presence of hydrogen peroxide (H2O2) as electrochemical substrate. Human serum samples were used for the respective assays. For the carbon substrate, three layers of CG proved to be sufficient for the optimization of electrochemical parameters and subsequent immobilization of the antigen, the immobilization step of the N protein was confirmed through changes in the electrochemical response of the immunosensor, the best time for its immobilization as 30 minutes. In the chronoamperometric response, a variation in anodic current values was recorded for samples with IgG-positive diagnoses when compared to negative samples, corroborating the results available through the ELISA technique