Trace detection of SARS-CoV-2 N-protein by diamond solution-gate field-effect transistor

In this study, we introduced H-terminated diamond solution-gate field-effect transistor (H-diamond SGFET) to detect trace SARS-CoV-2 N-protein, which plays an important role in replication and transcription of viral RNA. 1-Pyrenebutyric acid-N-hydroxy succinimide ester (Pyr-NHS) was modified on H-diamond surface as linker, on which the specific antibody of SARS-CoV-2 N-protein was catenated. Fourier transform infrared spectrum, scanning electron microscope and energy dispersive spectrum were utilized to demonstrate the modification of H-diamond with Pyr-NHS and antibody. Shifts of I(DS(max)) at V(GS) = −500 mV in transfer characteristics of H-diamond SGFET was observed to determine N-protein concentration in phosphate buffer solution. Good linear relationship between I(DS(max)) and log(10)(N-protein) was observed from 10(−14) to 10(−5) g/mL with goodness of fit R(2) = 0.90 and sensitivity of 1.98 μA/Log(10) [concentration of N-protein] at V(DS) = −500 mV, V(GS) = −500 mV. Consequently, this prepared H-diamond SGFET biosensor may provide a new idea for diagnosis of SARS-CoV-2 due to a wide detection range from 10(−14) to 10(−5) g/mL and low limit of detection 10(−14) g/mL.