Development immobilization of DNA onto a carbon nanotube modified electrode and characterization by electrochemical techniques

چکیده مقاله

In recent years, DNA-based diagnostic tests especially electrochemical DNA biosensors play an important role in clinical genetic analysis because the feasibility of using electrochemical techniques. The process of immobilization of DNA probes on solid surfaces is one of the essential steps toward to DNA sensor development. Up to now, a variety of techniques have been developed for the surface-capturing DNA probes onto transducer surfaces such as electrostatic attraction [1], covalent binding, controlled potential adsorption [2], and via the biotin–avidin interaction [3]. In the present study, we propose a rapid and simple strategy to the immobilization process of single strand DNA (ss-DNA) on modified glassy carbon electrode (GCE) surface. The functionalized multi walled carbon nanotubes (MWCNTs) can be successfully employed for the immobilization of ss-DNA through covalent interaction between this macromolecule and carboxylated MWCNTs (MWCNT-COOH). The both cyclic voltammetry and electrochemical impedance spectroscopy (EIS) provide evidence for the probe immobilization with the use of ferro-ferric cyanide as an electrochemical redox indicator. The peak potential separation (ΔEp = Epa - Epc) were found 0.087 and 0.174 V for MWCNT-COOH/GCE and ss-ss-DNA/MWCNT-COOH/GCE, respectively. The obtained results shows that ss-DNA sequense have been successfully immobilized on MWCNT-COOH/GCE. The value of -46.24 kJ mol-1 was calculated for the standard free-energy of adsorption (ΔG°ads) at different concentration of ss-DNA which suggests the formation of covalent bonds. The key parameters for covalent immobilization of DNA probe such as buffer conditions and time has been studied in order to optimize this methodology. The knowledge gained from this report offer new opportunities to future design of novel nucleic acid biosensor.