Single-Walled Carbon Nanotubes Modified Graphite Electrodes for Electrochemical Monitoring of Nucleic Acids and Biomolecular Interactions

Single-walled carbon nanotubes (SWCNT) modified disposable graphite electrodes (SWCNT-PGEs) were investigated in our study for the improved electrochemical monitoring of nucleic acids and biomolecular interactions based on the higher signal enhancement comparison to bare PGEs. The surface morphologies of bare PGE and SWCNT-PGE were firstly explored using scanning electron microscopy (SEM) analysis. The easy surface modification of disposable graphite electrodes with carbon nanotubes was performed by passive adsorption, and DNA was then immobilized onto the SWCNT-PGEs by the formation of covalent coupling between the carboxylated ends of nanotubes and the amine group in the guanine bases of DNA. The overall performance of SWCNT-PGEs has also been studied, and discussed in terms of optimum analytical conditions; such as, the effect of pretreatment step, CNT concentration, DNA concentration, etc. The reproducible detection of DNA represent a very attractive approach for the further detection of interaction between the anticancer drug, daunorubicin (DNR) and double stranded DNA (dsDNA). Voltammetric results were complemented with electrochemical impedance spectroscopy (EIS), that was used to characterize the successful construction of carbon nanotubes modification onto the surface of PGEs.