Development and characterisation of cysteine-based gold electrodes for the electrochemical biosensing of the SARS-CoV-2 spike antigen

• Published in: Analyst (London) Vol. 147; no. 2; pp. 4462 - 4472
• Main Authors: Olgaç, Nursel, ahin, Yücel, Liv, Lokman
• Format: Journal Article
• Language: English
• Published: London Royal Society of Chemistry 10.10.2022
• Subjects: Antibodies; Antigens; Biosensors; Carboxylic acids; Cattle; Coronaviruses; Cysteine; Electrodes; Glassy carbon; Photoelectrons; Platforms; Proteins; Reagents; Saliva; Serum albumin; Severe acute respiratory syndrome coronavirus 2; Spectrum analysis; Square waves; Voltammetry; X-ray spectroscopy
• ISSN: 0003-2654; 1364-5528
• DOI: 10.1039/d2an01225a

This article describes three novel electrochemical biosensing platforms developed to determine the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) spike antigen protein: glutaraldehyde, SARS-CoV-2 spike antibody and bovine serum albumin; N , N -dicyclohexyl carbodiimide/4-(dimethylamino)pyridine functionalised SARS-CoV-2 spike antibody and bovine serum albumin; and 1-ethyl-3-[3-dimethylaminopropyl]-carbodiimide hydrochloride/ N -hydroxysuccinimide functionalised SARS-CoV-2 spike antibody and bovine serum albumin modified cysteine-based gold-flower modified glassy carbon electrodes. Two of the produced biosensors having better signals were used to determine the SARS-CoV-2 spike antigen in spiked-saliva and clinical samples containing gargle and mouthwash liquids and characterised using cyclic voltammetry, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The study provides highly significant information in terms of how coupling reagents ought to be used with linkers consisting of both amine and carboxylic acid terminals ( i.e. cysteine). The electrochemical cathodic signals based on antibody-antigen protein interactions at approximately −270 mV were evaluated as a response using square wave voltammetry, and they increased in proportion to the SARS-CoV-2 spike antigen. The limit of detection values were 0.93 and 46.3 ag mL −1 in a linear range from 1 ag mL −1 to 100 pg mL −1 and from 100 ag mL −1 to 10 ng mL −1 and the recovery and relative standard deviation values for spiked-saliva samples were 99.50% and 99.40%, and 3.87% and 0.13% for BSA/S-AB/GluAl/Cys/Au/GCE and BSA/S-AB/ f -Cys/Au/GCE, respectively. The results showed that both biosensing platforms could be selectively and accurately used to diagnose COVID-19 in RT-PCR-approved clinical samples. Cysteine-based two novel biosensing platforms were used for determining the SARS-CoV-2 spike antigen protein in spiked-saliva and clinical samples.