Carboxylated graphene: A novel approach for enhanced IgA-SARS-CoV-2 electrochemical biosensing

Biosensors comprise devices that use a material of biological nature as receptors connected to transducers, these devices are capable of capturing biorecognition signals, called a primary signal, and converting it to a measurable signal. In this study, we report the synthesis of carboxylated graphene (CG) through a carboxylation method in acid medium and further characterization of the materials by different techniques such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, thermal gravimetric analysis (TGA), and X-ray diffraction (DRX). Also, the surface of the screen-printed carbon electrodes (SPCEs) was modified with CG for subsequent immobilization of N-protein of SARS-CoV-2, which allowed the detection of antibodies (IgA-SARS-CoV-2). The electrical properties and response of the biosensor were investigated using electrochemical techniques (cyclic voltammetry and electrochemical impedance spectroscopy). Through the chemical characterization techniques, it was possible to confirm the success of the CG synthesis process. The biosensor fabricated shown to be able to detect IgA-SARS-CoV-2 in the range of 1:1000 to1:200 v/v in phosphate buffer solution (PBS) and the limit of detection calculated was 1:1601 v/v. this perspective they comprise a wide range of applications due to its advantages, such as the possibility of a shorter response time, reproducibility, the miniaturization of detection devices such as the use of screen-printed electrodes, the use of small amounts of sample, the high sensitivity and specificity, low limits of detection and the integration of nano materials that make it possible to improve the detected signal.