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Anal Bioanal Chem ; 413(22): 5619-5632, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-2174032


In the face of the COVID-19 pandemic, the need for rapid serological tests that allow multiplexing emerged, as antibody seropositivity can instruct about individual immunity after an infection with SARS-CoV-2 or after vaccination. As many commercial antibody tests are either time-consuming or tend to produce false negative or false positive results when only one antigen is considered, we developed an automated, flow-based chemiluminescence microarray immunoassay (CL-MIA) that allows for the detection of IgG antibodies to SARS-CoV-2 receptor-binding domain (RBD), spike protein (S1 fragment), and nucleocapsid protein (N) in human serum and plasma in less than 8 min. The CoVRapid CL-MIA was tested with a set of 65 SARS-CoV-2 serology positive or negative samples, resulting in 100% diagnostic specificity and 100% diagnostic sensitivity, thus even outcompeting commercial tests run on the same sample set. Additionally, the prospect of future quantitative assessments (i.e., quantifying the level of antibodies) was demonstrated. Due to the fully automated process, the test can easily be operated in hospitals, medical practices, or vaccination centers, offering a valuable tool for COVID-19 serosurveillance. Graphical abstract.

Antibodies, Viral/blood , COVID-19 Serological Testing/methods , Immunoassay/methods , Immunoglobulin G/blood , SARS-CoV-2/immunology , Antigens, Viral/chemistry , Antigens, Viral/immunology , Automation, Laboratory , Coronavirus Nucleocapsid Proteins/immunology , Humans , Immobilized Proteins/chemistry , Immobilized Proteins/immunology , Immune Sera , Immunoassay/instrumentation , Lab-On-A-Chip Devices , Luminescent Measurements , Phosphoproteins/immunology , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Time Factors
Anal Chem ; 93(3): 1826-1833, 2021 01 26.
Article in English | MEDLINE | ID: covidwho-997756


Collection of nasopharyngeal samples using swabs followed by the transfer of the virus into a solution and an RNA extraction step to perform reverse transcription polymerase chain reaction (PCR) is the primary method currently used for the diagnosis of COVID-19. However, the need for several reagents and steps and the high cost of PCR hinder its worldwide implementation to contain the outbreak. Here, we report a cotton-tipped electrochemical immunosensor for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus antigen. Unlike the reported approaches, we integrated the sample collection and detection tools into a single platform by coating screen-printed electrodes with absorbing cotton padding. The immunosensor was fabricated by immobilizing the virus nucleocapsid (N) protein on carbon nanofiber-modified screen-printed electrodes which were functionalized by diazonium electrografting. The detection of the virus antigen was achieved via swabbing followed by competitive assay using a fixed amount of N protein antibody in the solution. A square wave voltammetric technique was used for the detection. The limit of detection for our electrochemical biosensor was 0.8 pg/mL for SARS-CoV-2, indicating very good sensitivity for the sensor. The biosensor did not show significant cross-reactivity with other virus antigens such as influenza A and HCoV, indicating high selectivity of the method. Moreover, the biosensor was successfully applied for the detection of the virus antigen in spiked nasal samples showing excellent recovery percentages. Thus, our electrochemical immunosensor is a promising diagnostic tool for the direct rapid detection of the COVID-19 virus that requires no sample transfer or pretreatment.

COVID-19/diagnosis , Cotton Fiber , Electrochemical Techniques/methods , Immunoassay/methods , SARS-CoV-2/isolation & purification , Antibodies, Viral/immunology , Biosensing Techniques/instrumentation , Biosensing Techniques/methods , Carbon/chemistry , Coronavirus Nucleocapsid Proteins/chemistry , Coronavirus Nucleocapsid Proteins/immunology , Electrochemical Techniques/instrumentation , Electrodes , Gossypium/chemistry , Humans , Immobilized Proteins/chemistry , Immobilized Proteins/immunology , Immunoassay/instrumentation , Limit of Detection , Nanofibers/chemistry , Phosphoproteins/chemistry , Phosphoproteins/immunology , SARS-CoV-2/immunology
Biosens Bioelectron ; 171: 112709, 2021 Jan 01.
Article in English | MEDLINE | ID: covidwho-838449


Coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was classified as a pandemic by the World Health Organization and has caused over 550,000 deaths worldwide as of July 2020. Accurate and scalable point-of-care devices would increase screening, diagnosis, and monitoring of COVID-19 patients. Here, we demonstrate rapid label-free electrochemical detection of SARS-CoV-2 antibodies using a commercially available impedance sensing platform. A 16-well plate containing sensing electrodes was pre-coated with receptor binding domain (RBD) of SARS-CoV-2 spike protein, and subsequently tested with samples of anti-SARS-CoV-2 monoclonal antibody CR3022 (0.1 µg/ml, 1.0 µg/ml, 10 µg/ml). Subsequent blinded testing was performed on six serum specimens taken from COVID-19 and non-COVID-19 patients (1:100 dilution factor). The platform was able to differentiate spikes in impedance measurements from a negative control (1% milk solution) for all CR3022 samples. Further, successful differentiation and detection of all positive clinical samples from negative control was achieved. Measured impedance values were consistent when compared to standard ELISA test results showing a strong correlation between them (R2=0.9). Detection occurs in less than five minutes and the well-based platform provides a simplified and familiar testing interface that can be readily adaptable for use in clinical settings.

Antibodies, Viral/blood , Betacoronavirus/immunology , Biosensing Techniques/instrumentation , Clinical Laboratory Techniques , Coronavirus Infections/blood , Dielectric Spectroscopy/instrumentation , Pneumonia, Viral/blood , Antibodies, Viral/immunology , Biosensing Techniques/economics , COVID-19 , COVID-19 Testing , Clinical Laboratory Techniques/economics , Coronavirus Infections/diagnosis , Coronavirus Infections/economics , Coronavirus Infections/immunology , Dielectric Spectroscopy/economics , Electric Impedance , Equipment Design , Humans , Immobilized Proteins/immunology , Pandemics , Pneumonia, Viral/diagnosis , Pneumonia, Viral/immunology , SARS-CoV-2 , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus/immunology , Time Factors