Impedancia Adn

DNA Conformational Transitions at Different Concentrations and Temperatures Monitored by EIS
L. M. Bravo-Anaya, E. R. Macías, F. Carvajal Ramos, V. V. A. Fernández, N. Casillas, J. F. A. Soltero and E. R. Larios-Durán ECS Electrochem. Lett. 2012, Volume 1, Issue 2, Pages G1-G3. doi: 10.1149/2.014202eel Email alerting service
Receive free email alerts when new articles cite this article - signup in the box at the top right corner of the article or click here

To subscribe to ECS Electrochemistry Letters go to: http://eel.ecsdl.org/subscriptions

© 2012 The Electrochemical Society

Downloaded on 2012-08-28 to IP 148.202.38.26 address. Redistribution subject to ECS license or copyright; see www.esltbd.org

2162-8726/2012/1(2)/G1/3/$28.00 © The Electrochemical Society

ECSElectrochemistry Letters, 1 (2) G1-G3 (2012)

G1

DNA Conformational Transitions at Different Concentrations and Temperatures Monitored by EIS
L. M. Bravo-Anaya,a E. R. Mac´as,a F. Carvajal Ramos,b V. V. A. Fern´ ndez,c N. Casillas,d,∗ ı a J. F. A. Soltero,a and E. R. Larios-Dur´ na,z a
a Universidad de Guadalajara, Departamento de Ingenier´a Qu´mica, C. P. 44430 Guadalajara, Jalisco, Mexico ı ıb Centro Universitario UTEG, Departamento de Investigaci´ n, C. P. 44460 Guadalajara, Jalisco, Mexico o c Universidad de Guadalajara, Departamento de Ciencias Tecnol´ gicas, C. P. 47819 Ocotl´ n, Jalisco, Mexico o a d Universidad

de Guadalajara, Departamento de Qu´mica, C. P. 44430 Guadalajara, Jalisco, Mexico ı

We present an EIS study and its analysis to determine the conformationalbehavior of DNA calf-thymus (13 kbp). The study is carried out at open circuit potential at a pH of 7.3. The results are interpreted in terms of the adsorption impedance theory by using an equivalent circuit approach similar to the one proposed by Frumkin-Melik-Gaikazyan-Randles. All equivalent circuit parameters are inspected as a function of DNA concentrations where it is possible to identify twotransitions on the double-layer structure at DNA ca. 0.33 ± 0.07 and 1.50 mg/mL related to the overlap, C*, and entanglement, Ce , concentrations. © 2012 The Electrochemical Society. [DOI: 10.1149/2.014202eel] All rights reserved. Manuscript submitted April 3, 2012; revised manuscript received May 29, 2012. Published July 20, 2012.

Electrochemical Impedance Spectroscopy (EIS) is an outstanding andnon-destructive technique suitable for investigating charged surfaces interacting with molecules such as DNA. Recent reports in the literature have demonstrated its potential to investigate DNA hybridization events that allow the development of DNA biossensing platforms, inmunosensors, and gene therapy.1–3 The last one requires a full understanding of DNA conformational changes before attempting atransfection process, which involves the collapsing of extended DNA chains into a more compact, arranged particles containing one or a few molecules before entering a cell.4,5 Since DNA is a complex charged molecule, it becomes evident that most of the conformational changes perceived for DNA strains in solution or interacting with charged electrode surfaces may depend on several parameters, suchas concentration, pH, temperature and polarization potential.6 One of the alternatives currently applied to investigate transitions in polymer science consists of measuring rheological properties at a frequency range (0.0016–16 Hz).7–9 Since DNA is a biopolymer it can be analyzed in a reometer with a cone-plate geometry, applying an oscillatory mode, while measuring the viscoelastic properties.8Thus, it is possible by this technique to derive two critical parameters sensible to DNA conformation, i.e. the overlap (C*) and the entanglement concentration (Ce ). The first one consists of a dilute polymer solution without any interaction between the molecules until reaching C*, where molecules start interacting each other and getting packed, then reaching the overlap concentration Ce , where...