Sensing of COVID-19 Antibodies in Seconds via Aerosol Jet Printed Three Dimensional Electrodes

Abstract

Rapid diagnosis is critical for the treatment and prevention of diseases. In this research, we report sensing of antibodies specific to SARS-CoV-2 virus in seconds via an electrochemical platform consisting of gold micropillar array electrodes decorated with reduced graphene oxide and functionalized with recombinant viral antigens. The array electrodes are fabricated by Aerosol Jet (AJ) nanoparticle 3D printing, where gold nanoparticles (3-5nm) are assembled in 3D space, sintered, and integrated with a microfluidic device. The device is shown to detect antibodies to SARS-CoV-2 spike S1 protein and its receptor-binding-domain (RBD) at concentrations down to 1pM via electrochemical impedance spectroscopy and read by a smartphone-based user interface. In addition, the sensor can be regenerated within a minute by introducing a low-pH chemistry that elutes the antibodies from the antigens, allowing successive testing of multiple antibody samples using the same sensor. The detection time for the two antibodies tested in this work is 11.5 seconds. S1 protein sensing of its antibodies is specific, which cross-reacts neither with other antibodies nor with proteins such as Nucleocapsid antibody and Interleukin-6 protein. The proposed sensing platform is generic and can also be used for the rapid detection of biomarkers for other infectious agents such as Ebola, HIV, and Zika, which will benefit the public health.

COVID-19 Antibody Tests and Their Limitations

“…These are usually in the form of sandwich immunoassays and are used more widely than the neutralization assays. Various binding antibody assays have been developed to detect immunoglobulins IgA, IgM, and IgG in blood against immunogenic proteins of SARS-CoV-2, including ELISA, 2 , 105 , 106 , 116 − 118 LFIA or ICG assay, 61 , 119 − 127 CLIA with enzyme 128 , 129 or nonenzyme labels, 92 , 130 electrochemiluminescence immunoassay (ECLIA), 131 fluorescence immunoassay (FIA), 86 protein microarrays, 132 − 135 biosensors, 136 , 137 and immunofluorescence assays (IFA). 138 − 140 …”

“…An electrochemical immunosensor combining an aerosol jet nanoprinted reduced-graphene-oxide-coated 3D electrode in a microfluidic device was developed to detect antibodies specific to SARS-CoV-2 within seconds. 137 Briefly, gold micropillar array electrodes, fabricated by aerosol jet nanoparticle 3D-printing, are functionalized by nanoflakes of reduced graphene oxide, which are in turn decorated with viral antigens. The functionalized electrode is then integrated with a microfluidic device to form a standard electrochemical cell.…”

On the Challenges for the Diagnosis of SARS-CoV-2 Based on a Review of Current Methodologies

“…This was the case of detection of SARS-CoV-2 S1 subunit antibodies using recombinant antigens on gold micropillar electrodes decorated with graphene oxide. 184 The LOD was 1 pmol L –1 with a detection time of 11.5 s with a smartphone-based interface, 184 but these devices may not be suitable for mass-testing because of the target analyte chosen by the authors: specific antibodies for S1 subunit proteins of SARS-CoV-2, which are not produced by a human infected organism. Instead, perhaps an electrochemical sensing platform for detecting IgG and IgM antibodies may be a more efficient strategy.…”

Emerging materials for the electrochemical detection of COVID-19

“…Very recently Ali et al [74] , exploiting the novel aerosol jet 3D-printing method [86] , [87] , [88] along with the r-GO properties, fabricated 3D Au pillars, being decorated with r-Go nanoflakes ( Fig. 6 Ai) examined as transducer electrode in a novel SARS-CoV-2 capacitive sensor.…”

“…(Aii) Schematic representation of the electrical double layer (consisted of Helmholtz planes: OHP & IHP), created between the electrode and the electrolyte. (Aiii) After the targeted antibodies bound with electrode’s antigens, the charge capacitance increases with the increase of the double layer width [74] . (Bi) Schematic illustration of the Au nanoparticles treatment.…”