Rapid single-molecule detection of COVID-19 and MERS antigens via nanobody-functionalized organic electrochemical transistors

• Published in: Nature biomedical engineering Vol. 5; no. 7; pp. 666 - 677
• Main Authors: Guo, Keying, Wustoni, Shofarul, Koklu, Anil, Díaz-Galicia, Escarlet, Moser, Maximilian, Hama, Adel, Alqahtani, Ahmed A., Ahmad, Adeel Nazir, Alhamlan, Fatimah Saeed, Shuaib, Muhammad, Pain, Arnab, McCulloch, Iain, Arold, Stefan T., Grünberg, Raik, Inal, Sahika
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2021; Nature Publishing Group
• Subjects: 631/61/338/552; 639/301/1005/1007; 82/1; 82/83; 9/10; 96; Antigens; Biomedical and Life Sciences; Biomedical Engineering/Biotechnology; Biomedicine; Biosensing Techniques - methods; Body fluids; Coronaviruses; COVID-19; COVID-19 - virology; Fluorescence; Green fluorescent protein; Humans; Middle East respiratory syndrome; Middle East Respiratory Syndrome Coronavirus - pathogenicity; Nanobodies; Nanotechnology - methods; Pandemics; Polymers; Proteins; Respiratory diseases; Saliva; Semiconductor devices; Sensors; Severe acute respiratory syndrome coronavirus 2; Severe acute respiratory syndrome-related coronavirus - pathogenicity; Single-Domain Antibodies - immunology; Transistors; Viral diseases
• ISSN: 2157-846X; 2157-846X
• DOI: 10.1038/s41551-021-00734-9

The coronavirus disease 2019 (COVID-19) pandemic has highlighted the need for rapid and sensitive protein detection and quantification in simple and robust formats for widespread point-of-care applications. Here, we report on nanobody-functionalized organic electrochemical transistors with a modular architecture for the rapid quantification of single-molecule-to-nanomolar levels of specific antigens in complex bodily fluids. The sensors combine a solution-processable conjugated polymer in the transistor channel and high-density and orientation-controlled bioconjugation of nanobody–SpyCatcher fusion proteins on disposable gate electrodes. The devices provide results after 10 min of exposure to 5 μl of unprocessed samples, maintain high specificity and single-molecule sensitivity in human saliva and serum, and can be reprogrammed to detect any protein antigen if a corresponding specific nanobody is available. We used the sensors to detect green fluorescent protein, and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and Middle East respiratory syndrome coronavirus (MERS-CoV) spike proteins, and for the COVID-19 screening of unprocessed clinical nasopharyngeal swab and saliva samples with a wide range of viral loads. Organic electrochemical transistors functionalized with antigen-specific nanobodies can rapidly detect attomolar-to-nanomolar levels of the antigens in complex bodily fluids.