Organic Electrochemical Transistor-Based Immunosensors for SARS-CoV-2 Detection

Following the emergence of the worldwide severe respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the need for innovative strategies and methodologies to facilitate cost-effective and early stage diagnosis has become evident. To prevent the outbreak of such contagious diseases, an efficient approach is systematic testing of the population. Here, we introduce a planar organic electrochemical transistor (OECT)-based immunosensor for the detection of SARS-CoV-2. The gold gate electrode of the poly(3,4-ethylenedioxy-thiophene):polystyrene sulfonate (PEDOT:PSS)-based OECTs was functionalized with SARS-CoV-2 antibodies. The detection mechanism is based on the specific interaction of the antibodies with the spike protein of the virus, allowing its direct detection and not requiring the prior formation of antibodies in the patient's body. As a proof of concept, the ability of the immunosensor to detect the SARS-CoV-2 spike protein is assessed. The sensor exhibits a remarkably low limit of detection (LOD) of 10–17 M, with an incubation time of 30 min. Furthermore, the sensors demonstrate selectivity when exposed to similar proteins and stability, retaining their LOD after 20 days of storage. Lastly, the functionalization protocol may easily be adapted for other pathogens/biomarkers, enabling not only a point-of-care device for SARS-CoV-2 detection but also a versatile platform for biosensing applications.