Diagnostics of SARS-CoV-2 infection using electrical impedance spectroscopy with an immunosensor to detect the spike protein

Electrochemical immunosensors using electrodeposited gold nanostructures for detecting the S proteins from SARS-CoV and SARS-CoV-2

“…After 2 h, electrodes were washed with ultrapure water and dried using a low N 2 stream. Next, 20 µL of a mixture of EDC and NHS (10 mmol L −1 and 20 mmol L −1 respectively) in MES buffer 100 mmol L −1 (pH 6.0) was incubated on the modified electrode for 1 h to promote the antibody attachment on the carboxylic groups [12,[31][32][33][34]. The electrodes were then rinsed using MES buffer (100 mmol L −1 , pH 6.0) and dried using N 2 .…”

“…The electrodes were then rinsed using MES buffer (100 mmol L −1 , pH 6.0) and dried using N 2 . Twenty microliters of 1 µg mL −1 anti-protein S antibodies (PBS, 0.1 mol L −1 , pH 7.0) was added to the electrode for 1 h. The antibody's concentration applied is within the concentration range reported in the literature for the manufacture of immunosensors used for SARS-CoV-2 detection, which range from 1 ng L −1 to 100 µg L −1 [31,32,[35][36][37][38][39][40]. Electrodes were washed using PBS (0.1 mol L −1 , pH 7.0) and dried with an N 2 gas stream.…”

Immunoassay platform with surface-enhanced resonance Raman scattering for detecting trace levels of SARS-CoV-2 spike protein

“…They are grouped on the bottom right of the Sammon's mapping, highlighting the ability of our SERRS immunoassay platform to also distinguish interferents. Soares et al [ 22 ] developed a biosensor capable to differentiate various concentrations of SARS-CoV-2 antigen from control experiments (interferents) applying IDMAP technique to analyze electrical impedance spectroscopy measurements. Moreover, SARS-CoV-2 antigens embedded into to the interferents could also be discriminated, as shown in Figure S2 .…”

“…Biosensors with distinct architectures have been developed for early detection of Covid-19, with the spike protein being the most used biomolecule for diagnosis. For instance, Soares et al [ 22 ] developed an immunosensor made of carboxymethyl chitosan coated with an active layer of specific antibodies, capable to detect the spike protein via electrical impedance spectroscopy. The spike protein could also be detected in sensing chips containing metamaterials and using terahertz time-domain spectroscopy [ 23 ], and with magnetic microrobots immuno-sandwich assays [ 24 ].…”

Electrochemical Impedance Spectroscopy (EIS) Based Label-Free Immunosensors

“…Chitosan is popular for electrode modifications due to its available amino groups, good adhesion and biocompatibility [93][94] . For example, Soares et al 95 have reported a low-cost impedimetric biosensor for detection of spike protein of SARS-CoV-2 virus based on carboxymethyl chitosan which was used as a matrix for the antibodies immobilisation via carbodiimide chemistry. The developed biosensor has a limit of detection of 0.179 fg/mL for SARS-CoV-2 spike protein with high selectivity.…”