Functionalized Titanium Dioxide Nanoparticle-Based Electrochemical Immunosensor for Detection of SARS-CoV-2 Antibody

The advancement in biosensors can overcome the challenges faced by conventional diagnostic techniques for the detection of the highly infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Hence, the development of an accurate, rapid, sensitive, and selective diagnostic technique can mitigate adverse health conditions caused by SARS-CoV-2. This work proposes the development of an electrochemical immunosensor based on bio-nanocomposites for the sensitive detection of SARS-CoV-2 antibodies through the differential pulse voltammetry (DPV) electroanalytical method. The facile synthesis of chitosan-functionalized titanium dioxide nanoparticles (TiO₂-CS bio-nanocomposites) is performed using the sol-gel method. Characterization of the TiO₂-CS bio-nanocomposite is accomplished using UV-vis spectroscopy, Raman spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The electrochemical performance is studied using cyclic voltammetry (CV), DPV, and electrochemical impedance spectroscopy (EIS) for its electroanalytical and biosensing capabilities. The developed immunosensing platform has a high sensitivity with a wide range of detection from 50 ag mL^-1 to 1 ng mL^-1. The detection limit of the SARS-CoV-2 antibody in buffer media is obtained to be 3.42 ag mL^-1 and the limit of quantitation (LOQ) to be 10.38 ag mL^-1. The electrochemical immunosensor has high selectivity in different interfering analytes and is stable for 10 days. The results suggest that the developed electrochemical immunosensor can be applicable for real sample analysis and further high-throughput testing.