Rapid detection of SARS-CoV-2 in wastewater using highly sensitive reduced graphene oxide (rGO)-based biosensors

Abstract

The coronavirus disease 2019 (COVID-19) outbreak, caused by SARS-CoV-2, has been declared a pandemic due to its rapid spread and enormous risk on public health. So far, qRT PCR is the mostly used diagnostic tool for COVID-19, despite the urgency of the pandemic. In spite of its accuracy, qRT-PCR is a time-consuming method that requires administration in expensive labs with highly trained personnel. Thus, several biosensors have been developed for the detection of SARS-CoV-2 in synthetic and clinical samples. Wastewater-based epidemiology (WBE) is confirmed to be a viable method to track the COVID-19 outbreak. This paper investigates, for the first time, the on-site detection of SARS-CoV-2 in wastewater using the proposed biosensor without prior spiking or viral concentration. A reduced graphene oxide based biosensor is proposed for the rapid, sensitive, and selective detection of SARS-CoV-2. In-house prepared graphene oxide was spin-coated and thermally reduced to form conductive reduced graphene oxide films, serving as sensing platforms for the reported immunosensor. The device was based on simple four-terminal Kelvin sensing, through which real-time data was obtained and analyzed. The biosensor achieves a LOD of 0.5 fg/mL in PBS, and verifies specificity against BSA protein, commercial vegan protein, glucosidase, and SARS-CoV-2 Nucleocapsid protein. The response time was measured to be around 240 ms. To further explore the biosensor's capability in wastewater, samples were collected from various locations around the United Arab Emirates (UAE). To detect SARS-CoV-2 in wastewater and evaluate the biosensor's performance, three different tests were conducted: qRT-PCT, commercial rapid test, and the proposed method. qRT-PCR was used to quantify SARS-CoV-2 concentrations in wastewater. Evidently, the reported biosensor outperforms the rapid test in wastewater diagnosis with a very low LOD of 2.91 copies/mL.

Date of Award	May 2022
Original language	American English