Chronocoulometric quantum dot aptasensor for sarscov-2 nucleocapsid protein biomarker

Abstract

For the first time, a novel mercaptosuccinic acid-capped tungsten telluride quantum dot (MSA-WTe3-QD)-based electrochemical aptasensor was designed for the determination of SARS-CoV-2 N-protein in synthetic human serum, plasma and urine. The MSA-WTe3-QD which exhibited spherical morphology and an average diameter of 3.56 nm were synthesized through a bottom-up approach. The aptasensor was prepared by firstly immobilizing MSA-WTe3-QD on a screen-printed carbon electrode (SPCE) by using the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling chemistry. Thereafter, amine-terminated 90-mer ssDNA aptamer was deposited on the modified SPCE and left to cure to form the aptasensor. Using the chronocoulometry signal transduction technique, the aptasensor's calibration with N-protein gave a linear range value of 1–9 pg.mL−1 and a limit of detection (LOD) value of 0.08 pg.mL−1. The LOD value of the aptasensor was 8 times lower than the LOD value of 0.71 pg.mL−1 obtained with a commercial N-protein ELISA kit. When tested in simulated real samples the aptasensor recovery rates of 95–103.33 % were obtained. In the presence of various interferents, the aptasensor displayed good selectivity to N-protein.