Search

The serologic diagnosis of coronavirus disease 2019 (COVID-19) and the evaluation of vaccination effectiveness are identified by the presence of antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this paper, we present the electrochemical-based biosensing technique for the detection of antibodies specific to the SARS-CoV-2 proteins. Recombinant SARS-CoV-2 spike proteins (rSpike) were immobilised on the surface of a gold electrode modified by a self-assembled monolayer (SAM). This modified electrode was used as a sensitive element for the detection of polyclonal mouse antibodies against the rSpike (anti-rSpike). Electrochemical impedance spectroscopy (EIS) was used to observe the formation of immunocomplexes while cyclic voltammetry (CV) was used for additional analysis of the surface modifications. It was revealed that the impedimetric method and the elaborate experimental conditions are appropriate for the further development of electrochemical biosensors for the serological diagnosis of COVID-19 and/or the confirmation of successful vaccination against SARS-CoV-2.

Herein we report the electrochemical system for the detection of specific antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins in blood serum patient samples after coronavirus disease 2019 (COVID-19). For this purpose, the recombinant SARS-CoV-2 spike protein (SCoV2-rS) was covalently immobilised on the surface of the gold electrode pre-modified with mixed self-assembled monolayer (SAMmix) consisting of 11-mercaptoundecanoic acid and 6-mercapto-1-hexanol. The affinity interaction of SCoV2-rS with specific antibodies against this protein (anti-rS) was detected using two electrochemical methods: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The anti-rS was detected with a detection limit of 2.53 nM and 1.99 nM using CV and EIS methods, respectively. The developed electrochemical immunosensor is suitable for the confirmation of COVID-19 infection or immune response in humans after vaccination.

After performing comparative coating thickness measurements using magnetic. coulometric and profilographic methods it has been determined that the coating thickness value obtained by the magnetic method is lower than the actual value, measured by the profilographic method. The measurements of hot-dip coatings with a thickness of 15-20 μm using a magnetic coating thickness gauge have shown that the measurement error may reach 32 %. An introduction of a correction factor equal to 1.3 was proposed.