Poly(3,4-ethylenedioxythiophene) Nanorod Arrays-Based Organic Electrochemical Transistor for SARS-CoV-2 Spike Protein Detection in Artificial Saliva.

The outbreak and continued spread of coronavirus disease 2019 (COVID-19) have significantly threatened public health. Antibody testing is essential for infection diagnosis, seroepidemiological analysis, and vaccine evaluation. However, achieving convenient, fast, and accurate detection remains challenging in this prolonged battle. This study reports a highly sensitive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein detection platform based on organic electrochemical transistors (OECTs) for biosensing applications. We developed a nanostructured poly(3,4-ethylenedioxythiophene) (PEDOT) conductive polymer with the carboxylic acid functional group (PEDOTAc) for modifying specific antibodies on an OECT channel for the detection of the COVID-19 spike protein. The OECT device features a channel composed of a PEDOT:polystyrenesulfonate (PEDOT:PSS) bottom layer, with the upper layer decorated with PEDOTAc nanorod arrays via the oxidative polymerization and a trans-printing method. Our novel PEDOTAc nanorod array-based OECT device exhibits promising potential for future healthcare and point-of-care sensing due to its rapid response, high sensitivity, and high accuracy. Through optimization, we achieved specific detection of the SARS-CoV-2 spike protein within minutes, with a detectable region from 10 fM to 100 nM. These biosensors hold significant promise for use in the diagnosis and prognosis of COVID-19.