An electrochemical immunosensor for the corona virus associated with the Middle East respiratory syndrome using an array of gold nanoparticle-modified carbon electrodes

The Middle East respiratory syndrome corona virus (MERS-CoV) is highly pathogenic. An immunosensor for the determination of MERS-CoV is described here. It is based on a competitive assay carried out on an array of carbon electrodes (DEP) modified with gold nanoparticles. Recombinant spike protein S1 was used as a biomarker for MERS CoV. The electrode array enables multiplexed detection of different CoVs. The biosensor is based on indirect competition between free virus in the sample and immobilized MERS-CoV protein for a fixed concentration of antibody added to the sample. Voltammetric response is detected by monitoring the change in the peak current (typically acquired at a working potential of −0.05 V vs. Ag/AgCl) after addition of different concentrations of antigen against MERS-CoV. Electrochemical measurements using ferrocyanide/ferricyanide as a probe were recorded using square wave voltammetry (SWV). Good linear response between the sensor response and the concentrations from 0.001 to 100 ng.mL ⁻¹ and 0.01 to 10,000 ng.mL ⁻¹ were observed for MERS-CoV and HCoV, respectively. The assay was performed in 20 min with detection limit as low as 0.4 and 1.0 pg.mL ⁻¹ for HCoV and MERS-CoV, respectively. The method is highly selective over non-specific proteins such as Influenza A and B. The method is single-step, sensitive and accurate. It was successfully applied to spiked nasal samples.