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

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.

Peptide-based simple detection of SARS-CoV-2 with electrochemical readout

“…In such biosensors, bioreceptors are anchored on the working electrode surface to directly bind to target molecules specifically, generating changes in the interfacial properties in a concentration-dependent manner [ [18] , [19] , [20] ]. The SARS-CoV-2 has also been detected electrochemically by immunosensors [ 14 , [21] , [22] , [23] , [24] , [25] , [26] , [27] , [28] , [29] , [30] , [31] , [32] ] and genosensors [ [33] , [34] , [35] , [36] ]. Furthermore, outstanding features of biosensors have been exploited in the detection of other viruses [ 37 , 38 ], pathogens [ 39 ], other infections [ 18 ], cancer biomarkers [ [40] , [41] , [42] ] and other diseases-related biomarkers [ 43 ] demonstrating to be promising analytical tools that can help to solve current diagnosis limitations [ 44 ].…”

Development of polypyrrole (nano)structures decorated with gold nanoparticles toward immunosensing for COVID-19 serological diagnosis

“…Among electrochemical biosensors available up to this day in the literature, there are a few works using EIS as a transducer [ [45] , [46] , [47] , [48] , [49] , [50] , [51] ], although just one impedimetric biosensor for antibody detection in serum samples. Rashed et al presented a very fast impedance sensing platform to detect SARS-CoV-2 antibodies in serum specimens, testing concentrations of 0.1, 1.0 and 10 μg mL.…”

Paper-Based Biosensors for COVID-19: A Review of Innovative Tools for Controlling the Pandemic

“…A similar approach was proposed by Ehsan et al , using screen printing for electrode patterning, a graphene/carbon hybrid ink for the working electrode, carbon ink for the counter, and Ag/AgCl for reference electrode fabrication. 121 The modification of the electrode was performed by an alternative method to the recurrent EDC/NHS covalent binding method, using PBASE for immobilization of anti-spike S1 unit IgG antibody. The developed electrochemical sensor was used to quantify the RBD in nasopharyngeal samples, with exceptional analytical parameters, with a limit of quantification of 0.25 fg/mL and a wide linear sensitivity range up to 1 μg/mL.…”