Screen-Printed Graphene/Carbon Electrodes on Paper Substrates as Impedance Sensors for Detection of Coronavirus in Nasopharyngeal Fluid Samples.

Muhammad Ali Ehsan,Safyan Akram Khan,Abdul Rehman

doi:10.3390/diagnostics11061030

Muhammad Ali Ehsan, Safyan Akram Khan + Show 1 more

Open Access

https://doi.org/10.3390/diagnostics11061030

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Abstract

Severe acute respiratory syndrome (SARS-CoV-2), the causative agent of the global pandemic, which has resulted in more than one million deaths with tens of millions reported cases, requires a fast, accurate, and portable testing mechanism operable in the field environment. Electrochemical sensors, based on paper substrates with portable electrochemical devices, can prove an excellent alternative in mitigating the economic and public health effects of the disease. Herein, we present an impedance biosensor for the detection of the SARS-CoV-2 spike protein utilizing the IgG anti-SARS-CoV-2 spike antibody. This label-free platform utilizing screen-printed electrodes works on the principle of redox reaction impedance of a probe and can detect antigen spikes directly in nasopharyngeal fluid as well as virus samples collected in the universal transport medium (UTM). High conductivity graphene/carbon ink is used for this purpose so as to have a small background impedance that leads to a wider dynamic range of detection. Antibody immobilization onto the electrode surface was conducted through a chemical entity or a biological entity to see their effect; where a biological immobilization can enhance the antibody loading and thereby the sensitivity. In both cases, we were able to have a very low limit of quantification (i.e., 0.25 fg/mL), however, the linear range was 3 orders of magnitude wider for the biological entity-based immobilization. The specificity of the sensor was also tested against high concentrations of H1N1 flu antigens with no appreciable response. The most optimized sensors are used to identify negative and positive COVID-19 samples with great accuracy and precision.

Highlights

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly contagious virus, transmissible from human to human [1], which has been classified as a global pandemic by the World Health Organization [2]
In the first case, (PBASE), an interface coupling agent typically used as a probe linker that binds to IgG, was immobilized on the hydrophilic cellulose paper pads
The activated carboxylic terminals of the graphene can be used to incorporate pyrenebutanoic acid succinimidyl ester (PBASE) and, later, for the attachment of IgG antibodies. Such interaction can occur between the graphene and pyrene groups of the PBASE to support this immobilization mechanism

Summary

Introduction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a highly contagious virus, transmissible from human to human [1], which has been classified as a global pandemic by the World Health Organization [2]. Despite the rollout of many vaccine candidates in the last few months [3], much of the world population is still effected by outbreaks as new variants are identified and low-income communities have no access to vaccines [4]. Even where these vaccines are available, economic activities are still hindered, with schools and colleges most affected by apprehensions of outbreaks. Batch fabricated mass diagnostic devices or biosensors are needed among these communities to reduce the number of undetected cases [9] Such an early and prompt diagnosis can play a crucial role for informed decisions concerning the isolation of infected patients. This, again, has an economic impact if a false positive person is isolated, while slowing the spread of this infectious disease by isolating the true positives [10,11,12]

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