Label-Free Electrochemical DNA Biosensor for the Detection of Mycobacterium Tuberculosis Using Gold Electrode Modified by Self-Assembled Monolayer of Thiol

Abstract

Tuberculosis (TB), an infectious disease affects millions of humans worldwide and is caused by the Mycobacterium tuberculosis. A label free electrochemical DNA biosensor for the detection of M. tuberculosis using gold electrode modified by self-assembled monolayer of thiol is presented in this paper. Single-stranded DNA probe was immobilized on the surface of self-assembled monolayer gold electrode with the assistance of cysteamine and glutaraldehyde, which was further used to hybridize with the target sequence and non-complementary target sequence. Differential Pulse Voltammetry (DPV) was used to characterize the self-assembled monolayer on the gold electrode and also to study the immobilization of ssDNA probe and hybridization with the complementary sequence (target ssDNA). The hybridization reaction on the gold electrode surface was detected by monitoring a guanine oxidation signal at potential +0.21V. Electrochemical DNA biosensor using gold electrode modified of thiol (Au-SAM) can be used to determine hybridization between ssDNA probe and ssDNA target sequence of M. tuberculosis with sensitvity value is 0.5152; detection limit is 3.47μg.mL-1 and quantification limit is 11.56μg.mL-1