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

• Published in: 2d materials Vol. 9; no. 3; pp. 35016 - 35031
• Main Authors: Pola, Cícero C, Rangnekar, Sonal V, Sheets, Robert, Szydłowska, Beata M, Downing, Julia R, Parate, Kshama W, Wallace, Shay G, Tsai, Daphne, Hersam, Mark C, Gomes, Carmen L, Claussen, Jonathan C
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 01.07.2022
• Subjects: aerosol jet printing; biosensor; COVID-19; electrochemical impedance spectroscopy; graphene; COVID-19; aerosol jet printing; biosensor; electrochemical impedance spectroscopy; graphene
• ISSN: 2053-1583; 2053-1583
• DOI: 10.1088/2053-1583/ac7339

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.