Carbon nanotube-enhanced DNA biosensor for DNA hybridization detection using rutin-Mn as electrochemical indicator

Abstract

Abstract The manganese complex of rutin(R) C 54 H 58 MnO 32 (abbreviated by MnR 2 ) was synthesized and characterized by elemental analysis and IR spectroscopy. Cyclic voltammetry (CV) and fluorescence spectroscopy were used to investigate the interaction of MnR 2 with salmon sperm DNA. It was revealed that MnR 2 presented an excellent electrochemical activity on glassy carbon electrode (GCE) and could intercalate into the double helix of double-stranded DNA (dsDNA). A novel and sensitive electrochemical DNA biosensor based on multi-walled carbon nanotubes functionalized with a carboxylic acid group (MWCNTs–COOH) for covalent DNA immobilization and enhanced hybridization detection was described. The MWCNTs–COOH modified glassy carbon electrode was fabricated and oligonucleotides with the 5′-amino group were covalently bonded to the carboxyl group of carbon nanotubes. Compared with DNA sensors with oligonucleotides directly incorporated on glassy carbon electrodes, this carbon nanotube-based assay with its large surface area and good charge-transport characteristics dramatically increased DNA attachment quantity and complementary ssDNA detection sensitivity. The target ssDNA could be quantified ranged from 1.60 × 10 −9 M to 4.80 × 10 −8 M with good linearity ( r = 0.9898) and a detection limit of 3.81 × 10 −11 M (3 σ , n = 7) was achieved by the constructed electrochemical DNA biosensor.