Deenin W.Yakoh A.Pimpitak U.Pasomsub E.Rengpipat S.Crespo G.A.Chaiyo S.Mahidol University2023-05-162023-05-162023-08-01Bioelectrochemistry Vol.152 (2023)15675394https://repository.li.mahidol.ac.th/handle/20.500.14594/81372Antigen test kits (ATK) are extensively utilized for screening and diagnosing COVID-19 because they are easy to operate. However, ATKs exhibit poor sensitivity and cannot detect low concentrations of SARS-CoV-2. Herein, we present a new, highly sensitive, and selective device obtained by combining the principle of ATKs with electrochemical detection for COVID-19 diagnosis, which can be quantitatively assessed using a smartphone. An electrochemical test strip (E-test strip) was constructed by attaching a screen-printed electrode inside a lateral-flow device to exploit the remarkable binding affinity of SARS-CoV-2 antigen to ACE2. The ferrocene carboxylic acid attached to SARS-CoV-2 antibody acts as an electroactive species when it binds to SARS-CoV-2 antigen in the sample before it flows continuously to the ACE2-immobilization region on the electrode. Electrochemical-assay signal intensity on smartphones increased proportionally to the concentration of SARS-CoV-2 antigen (LOD = 2.98 pg/mL, under 12 min). Additionally, the application of the single-step E-test strip for COVID-19 screening was demonstrated using nasopharyngeal samples, and the results were consistent with those obtained using the gold standard (RT-PCR). Therefore, the sensor demonstrated excellent performance in assessing and screening COVID-19, and it can be used professionally to accurately verify diagnostic data while remaining rapid, simple, and inexpensive.ChemistryArticleSCOPUS10.1016/j.bioelechem.2023.1084382-s2.0-851521025891878562X37054603