Aerosol-jet-printed graphene electrochemical immunosensors for rapid and label-free detection of SARS-CoV-2 in saliva

Abstract

Rapid, inexpensive, and easy-to-use coronavirus disease 2019 (COVID-19) home tests are key tools in addition to vaccines in the world-wide fight to eliminate national and local shutdowns. However, currently available tests for SARS-CoV-2, the virus that causes COVID-19, are too expensive, painful, and irritating, or not sufficiently sensitive for routine, accurate home testing. Herein, we employ custom-formulated graphene inks and aerosol jet printing (AJP) to create a rapid electrochemical immunosensor for direct detection of SARS-CoV-2 Spike Receptor-Binding Domain (RBD) in saliva samples acquired non-invasively. This sensor demonstrated limits of detection that are considerably lower than most commercial SARS-CoV-2 antigen tests (22.91 ± 4.72 pg/mL for Spike RBD and 110.38 ± 9.00 pg/mL for Spike S1) as well as fast response time (~30 mins), which was facilitated by the functionalization of printed graphene electrodes in a single-step with SARS-CoV-2 polyclonal antibody through the carbodiimide reaction without the need for nanoparticle functionalization or secondary antibody or metallic nanoparticle labels. This immunosensor presents a wide linear sensing range from 1 to 1000 ng/mL and does not react with other coexisting influenza viruses such as H1N1 hemagglutinin. By combining high-yield graphene ink synthesis, automated printing, high antigen selectivity, and rapid testing capability, this work offers a promising alternative to current SARS-CoV-2 antigen tests.

The role of electrochemical biosensors in SARS-CoV-2 detection: a bibliometrics-based analysis and review

“…This means that two-dimensional materials have been used for the assembly of electrochemical biosensors. Pola et al 53 proposed an electrochemical immunosensor using graphene ink and aerosol jet printing technology that enables the detection of SARS-CoV-2 in saliva samples. Ang et al 54 used graphene oxide nanocolloids as a transduction platform and electroactive tag to enable the detection of SARS-CoV-2 genomic sequences.…”

A Brief Review of Graphene-Based Biosensors Developed for Rapid Detection of COVID-19 Biomarkers

“…et al [ 13 ] but the incubation of PBASE was performed overnight to ensure adherence of PBASE, presenting an increased probability of ssDNA binding onto the surface. Moreover, EDC/NHS was utilized by other research groups [ 18 , 19 , 20 ], where they pre-activated the carboxylic unit of PBASE. Immobilization of biorecognition molecules could possibly lead to non-specific interactions.…”

Functional Ink Formulation for Printing and Coating of Graphene and Other 2D Materials: Challenges and Solutions

“…Aerosol‐jet‐printed (AJP) graphene‐based dipstick functionalized electrodes were incubated with a SARS‐CoV‐2 spike then the electrode surface was blocked with buffer until further testing. [ 35 ] In Table 1 , some of the most promising graphene ink formulations for different printing and coating methods are summarized.…”