Development of paper-based electrochemical immunosensor for SARS-CoV-2 detection

Abstract

This dissertation aimed to develop a simple and low-cost electrochemical sensing platform for detecting SAR-CoV-2 antigen. The proposed sensor combined the innovative disposable paper-based immunosensor and cost-effective plant-based anti-SARS-CoV-2 monoclonal antibody, extracted from Nicotiana benthamiana. The cellulose nanocrystal was modified on screen-printed graphene electrode to provide the COOH functional groups on electrode surface, leading to the high ability for antibody immobilization. The quantification of the presence receptor binding domain (RBD) spike protein of SARS-CoV-2 was performed using differential pulse voltammetry by monitoring the changing current of [Fe(CN)6]3-/4- redox solution. The current change of [Fe(CN)6]3-/4- before and after the presence of target RBD could be clearly distinguished, providing a linear relationship with RBD concentration in the range from 0.1 pg/mL to 500 ng/mL with the limit of detection of 2.0 fg/mL. The proposed platform was successfully applied to detect RBD in nasopharyngeal swab samples with satisfactory results. Furthermore, the paper-based immunosensor was extended to quantify the RBD level in spiked saliva samples, demonstrating the broadly applicability of this system. This paper-based electrochemical immunosensor has the potential to be employed as a point-of-care testing for COVID-19 diagnosis.