Pola Cícero C, Rangnekar Sonal V, Sheets Robert, Szydlowska Beata M, Downing Julia R, Parate Kshama W, Wallace Shay G, Tsai Daphne, Hersam Mark C, Gomes Carmen L, Claussen Jonathan C
Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA.
Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.
2d Mater. 2022 Jul;9(3). doi: 10.1088/2053-1583/ac7339. Epub 2022 Jun 10.
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.
快速、廉价且易于使用的2019冠状病毒病（COVID-19）家用检测试剂盒是全球抗击疫情、避免国家和地区封锁的关键工具，其重要性仅次于疫苗。然而，目前用于检测导致COVID-19的病毒SARS-CoV-2的检测方法，要么过于昂贵、操作痛苦且令人不适，要么对常规、准确的家用检测而言灵敏度不足。在此，我们采用定制配方的石墨烯墨水和气溶胶喷射打印（AJP）技术，开发了一种快速电化学免疫传感器，用于直接检测非侵入性采集的唾液样本中的SARS-CoV-2刺突受体结合域（RBD）。该传感器的检测限远低于大多数商用SARS-CoV-2抗原检测方法（刺突RBD为22.91±4.72 pg/mL，刺突S1为110.38±9.00 pg/mL），且响应时间快（约30分钟）。这得益于通过碳二亚胺反应，将印刷石墨烯电极与SARS-CoV-2多克隆抗体一步功能化，无需纳米颗粒功能化、二抗或金属纳米颗粒标记。这种免疫传感器具有1至1000 ng/mL的宽线性传感范围，且不与其他共存的流感病毒（如H1N1血凝素）发生反应。通过结合高产率石墨烯墨水合成、自动化打印、高抗原选择性和快速检测能力，本研究为当前的SARS-CoV-2抗原检测提供了一种有前景的替代方案。
