ABSTRACT
Objectives Sensor Biology and sensor devices have been advancing since its inceptions. In this work, we report fabrication of carbon nanotubes filed-effect transistor (CNT-FET) sensor and its characterization. CNT intensively has been used in the construction of sensing layers due to their exceptional features, large surface area, stability, high mechanical strength, adaptability, and functional behavior. Methods Carbon nanotubes (CNTs) as semiconductor were fabricated as an active nanomaterial between the source-drain electrodes. The fabrication of CNT-FETs performed by following conventional photolithography method and lift-off techniques. Results The structural morphology of deposited CNT was confirmed by the scanning electron micrograph (SEM) imaging. The transfer curves between drain-source were considered as a function of the drain-source voltage (VDS) and gate-source voltage (VGS) from individual CNT-FET fabricated wafer. The characterized Ion/Ioff ratio was calculated for every CNT-FET device. The semiconductor properties of the fabricated CNT-FET device characterized by the source-drain current (IDS) versus gate voltage (VGS). Conclusions CNT-FET based device have advantages of low cost fabrication, quick response, increased sensitivity, small size, and high flexibility. CNT-FETs have been used comprehensively in the biosensing of chemicals, proteins, nucleic acids, bacteria, and virus etc. This device could be used for SARS-CoV-2 and related variant detection in current scenario.
ABSTRACT
The large-scale diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is important for traceability and treatment during pandemic outbreaks. We developed a fast (2-3 min), easy-to-use, low-cost, and quantitative electrochemical biosensor based on carbon nanotube field-effect transistor (CNT-FET) that allows digital detection of the SARS-CoV-2 S1 in fortifited saliva samples for quick and accurate detection of SARS-CoV-2 S1 antigens. The biosensor was developed on a Si/SiO2 surface by CNT printing with the immobilization of a anti-SARS-CoV-2 S1. SARS-CoV-2 S1 antibody was immobilized on the CNT surface between the S-D channel area using a linker 1-pyrenebutanoic acid succinimidyl ester (PBASE) through non-covalent interaction. A commercial SARS-CoV-2 S1 antigen was used to characterize the electrical output of the CNT-FET biosensor. The SARS-CoV-2 S1 antigen in the 10 mM AA buffer pH 6.0 was effectively detected by the CNT-FET biosensor at concentrations from 0.1 fg/mL to 5.0 pg/mL. The limit of detection (LOD) of the developed CNT-FET biosensor was 4.12 fg/mL. The selectivity test was performed by using target SARS-CoV-2 S1 and non-target SARS-CoV-1 S1 and MERS-CoV S1 antigens in the 10 mM AA buffer pH 6.0. The biosensor showed high selectivity (no response to SARS-CoV-1 S1 or MERS-CoV S1 antigen) with SARS-CoV-2 S1 antigen detection in the 10 mM AA buffer pH 6.0. The biosensor is highly sensitive, saves time, and could be a helpful platform for rapid detection of SARS-CoV-2 S1 antigen from the patients saliva.