Electrochemical studies of DNA immobilization onto the2.pdf

Available online at /locate/yabio ANALYTICAL BIOCHEMISTRY Analytical Biochemistry 375 (2008) 331–338Electrochemical studies of DNA immobilization onto the azide-terminated monolayers and its interaction with taxol Ali Mehdinia a, S. Habib Kazemi a, S. Zahra Bathaie b, Abdolhamid Alizadeh c, Mojtaba Shamsipur c, Mir Fazlollah Mousavi a,* aDepartment of Chemistry, Tarbiat Modares University, Tehran, Iran bDepartment of Clinical Biochemistry, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran cDepartment of Chemistry, Razi University, Kermanshah, Iran Received 28 November 2007 Available online 10 January 2008Abstract A surface modification procedure for the creation of self-assembled monolayers (SAMs) that can be used as a scaffold for double- stranded DNA (dsDNA) incorporation onto the gold surfaces is described. The SAMs of an azidohexane thiol derivative were prepared on the Au electrode and then used for the immobilization of dsDNA. The electrochemical characteristics of dsDNA onto the SAM-mod- ified gold electrode were investigated by cyclic voltammetry and electrochemical impedance spectroscopy, and the surface concentration of dsDNA onto the SAMs surface was estimated. The interaction of dsDNA with the anticancer drug, taxol (paclitaxel), was also studied on the surface of DNA/SAM/Au electrode. The observed decrease in the guanine oxidation peak current was used to monitor the inter- action of taxol with DNA. The resulting Langmuir isotherm for taxol binding to DNA at the modified electrode was used to evaluate the binding constant of taxol–DNA. The results obtained supported the groove binding interaction of taxol with DNA. The modified elec- trode was used as a sensitive sensor for quantification of taxol in human serum sample.  2008 Elsevier Inc. All rights reserved. Keywords: Self-assembled monolayers; DNA; Taxol; Cyclic voltammetry; Electrochemical impedance spectroscopyA major challenge in the immobilization of a variety of biomolecules