Impedimetric immunosensor based on SWCNT-COOH modified gold microelectrodes for label-free detection of deep venous thrombosis biomarker

Abstract

Measurement of D-dimer has subsequently become an essential element in the diagnostics of deep vein thrombosis and pulmonary embolism; in this context microelectrodes with an area of 9×10(-4) cm(2) were used to develop impedimetric immunosensor for detecting deep venous thrombosis biomarker (D-dimer). The biosensor is based on functionalized carbon nanotubes (SWCNT-COOH) where the antibody (anti-D-dimer) was immobilized by covalent binding. The electrical properties and the morphology of the biolayer were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry and atomic force spectroscopy (AFM). Impedimetric microimmunosensor allows to obtain sensitivity of 40.1 kΩ μM(-1) and detection limit of 0.1 pg/mL (0.53 fM) with linear range from 0.1 pg/mL to 2 μg/mL (0.53 fM to 0.01 μM). We demonstrate that using carbon nanotubes and microelectrodes, high sensitivity and dynamic range were obtained. The biosensor exhibited a short response time of 10 min. Moreover, the studied immunosensor exhibits good reproducibility (R.S.D. 8.2%, n=4).