Abstract
Electrochemical biosensors for determining wildtype and omicron variant of the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) nucleocapsid antigen in nasopharyngeal swab samples were produced by using functionalised graphene oxide and the wildtype and omicron types of SARS-CoV-2 nucleocapsid antibody modified glassy carbon electrodes. The developed biosensors characterised by cyclic voltammetry, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy were able to detect 0.76 and 0.24 ag/mL of the wildtype and omicron SARS-CoV-2 nucleocapsid antigen protein in linear ranges varied from 1 ag/mL to 100 fg/mL and from 1 ag/mL to 10 fg/mL, respectively. The performance of both biosensors produced was compared in nasopharyngeal swab samples containing the wildtype and omicron variant of the SARS-CoV-2, and it was evaluated whether they could be used interchangeably.