Abstract
In this work, we developed an ultrasensitive and ultraselective electrochemical biosensor for detection of a specific sequence DNA. It was fabricated based on a glassy carbon electrode (GCE) modified with Multi-walled carbon nanotubes (MWCNTs)-Chitosan (CHIT) nanocomposite and a thin film of gold nanoparticles (AuNPs). Immobilization is based on the covalent reaction between thiol group in DNA probe and AuNPs on electrode surface. Cyclic Voltametry (CV) and Differential Pulse Voltammetry (DPV) techniques were used for hybridization detection by methylene blue (MB) as indicator. The surface modification increased significantly DNA immobilization quantity and complementary DNA detection sensitivity. The response signal increased linearly with the increase of the target DNA concentration in the range of (1 × 10-14 M to 9 × 10-14 M) with the detection limit of 7.2 fM (LOD =3SXm). The presented method exhibited excellent specificity and selectivity for complementary and single-mismatch, three-base-mismatch and non-complementary sequences of DNA.
Published Version
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