Electrochemical Impedance-Based Biosensors for the Label-Free Detection of the Nucleocapsid Protein from SARS-CoV-2

Abstract

Diagnosis of coronavirus disease (COVID-19) is important because of the emergence and global spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Real-time polymerase chain reaction (PCR) is widely used to diagnose COVID-19, but it is time-consuming and requires sending samples to test centers. Thus, the need to detect antigens for rapid on-site diagnosis rather than PCR is increasing. We quantified the nucleocapsid (N) protein in SARS-CoV-2 using an electro-immunosorbent assay (El-ISA) and a multichannel impedance analyzer with a 96-interdigitated microelectrode sensor (ToAD). The El-ISA measures impedance signals from residual detection antibodies after sandwich assays and thus offers highly specific, label-free detection of the N protein with low cross-reactivity. The ToAD sensor enables the real-time electrochemical detection of multiple samples in conventional 96-well plates. The limit of detection for the N protein was 0.1 ng/mL with a detection range up to 10 ng/mL. This system did not detect signals for the S protein. While this study focused on detecting the N protein in SARS-CoV-2, our system can also be widely applicable to detecting various biomolecules involved in antigen–antibody interactions.

Sensing Characteristics of SARS-CoV-2 Spike Protein Using Aptamer-Functionalized Si-Based Electrolyte-Gated Field-Effect Transistor (EGT)

“…However, this approach is unsuitable for point-of-care testing because it requires specialized laboratories, sophisticated and expensive equipment, and trained personnel. Alternatively, several other methods, including electrochemical techniques [ 8 , 9 ], fluorescence [ 10 , 11 ], and impedance [ 12 , 13 ], have been demonstrated. Among these, biosensor field-effect transistors (BioFETs) have emerged as a promising approach due to their low cost, ultra-sensitivity, and label-free detection [ 14 , 15 , 16 ].…”

Gold nanostructures modified carbon-based electrode enhanced with methylene blue for point-of-care COVID-19 tests using isothermal amplification

“…Decorating the working electrodes with synthesized gold nanostars (AuNSs) increases the surface area and improves the current density of the electrochemical signals. Although a few studies have been conducted on the label-free electrochemical detection of COVID-19, they rely on the redox response of sensors and use immobilized antibodies and nanocomposites to enhance detection [ [34] , [35] , [36] , [37] , [38] ]. Most techniques rely on the decrease in current response of a free-to-diffuse intercalating redox reporter during the reaction processes [ 39 , 40 ].…”

Portable microfluidic impedance biosensor for SARS-CoV-2 detection

“…Since the pandemic began, researchers have studied electrochemical biosensors for SARS-CoV-2 detection, comparing several methodologies and materials ( Alafeef et al, 2020 ; Amouzadeh Tabrizi et al, 2022 ; Antiochia, 2022 ; Ashur et al, 2022 ; Ayala-Charca et al, 2022 ; Cho et al, 2022 ; Ditte et al, 2021 ; Ehsan et al, 2021 ; Fabiani et al, 2021 ; Hashemi et al, 2021 ; Idili et al, 2021 ; Kiew et al, 2021 ; Kim et al, 2021 ; Lasserre et al, 2022 ; Rahmati et al, n.d. ; Rashed et al, 2021 ; Salahandish et al, 2022 ; Seo et al, 2020 ; Soares et al, 2022 ; Soto and Orozco, 2022 ; Tabrizi and Acedo, 2022 ; Torrente-Rodríguez et al, 2020 ; Torres et al, 2021 ; H. Z. Zhao et al, 2021 . However, although other techniques can be faster, electrochemical impedance spectroscopy or EIS-based biosensors are increasingly popular because they use a sensitive transduction technique that does not require labeling or amplification for analyte detection.…”