Sensing a SARS-CoV-2 spike peptide using a titanium carbide-doped imprinted polymer-coated extended-gate field effect transistor

The COVID-19 pandemic of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has over 750 million confirmed cases globally and more than six million deaths. Several variants have been named and identified as variants of concern by the World Health Organization (WHO); these include the Delta and Omicron variants. This work demonstrates the integration of epitope-imprinted conductive polymers with extended gate field effect transistors for the sensitive detection of the covid spike protein. Peptides from the receptor-binding domain on the spike protein were synthesized and imprinted onto poly(aniline-co-3-aminobenzenesulfonic acid), poly(AN-co-MSAN), by electropolymerization. Doping the conductive polymer film with titanium carbide (Ti₂C) strengthened the electrochemical response approximately 1.5-fold. The FET platform not only amplified the electrochemical response about two-fold (compared with electrode-based sensing), but also lowered the sensing range for the SARS-CoV-2 spike protein subunit S1 (ncovS1) from 1.0 to 0.01 fg/mL.