Naslov
Characterization of three-layered SAM by Electrochemical Impedance Spectroscopy

Autori
Kereković, Irena ; Milardović, Stjepan

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
YISAC2008-15th Young Investigators'Seminar on Analytical Chemistry / Prosen, Helena - Ljubljana : Fakulteta za kemijo in kemijsko tehnologijo Univerze v Ljubljani, 2008, 101-102

ISBN
978-961-6286-96-1

Skup
YISAC2008-15th Young Investigators'Seminar on Analytical Chemistry

Mjesto i datum
Ljubljana, Slovenija, 02.06.2008. - 05.06.2008

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
electrochemical impedance spectroscopy; sam;

Sažetak
Self-assembled monolayers (SAMs) are ordered molecular assemblies formed by the adsorption of an active surfactant molecule on a solid surface [1]. SAMs are highly stable, well organized structures and can be used in corrosion prevention and development of various detection systems. Scientific interest in them begun in 1946. when Zisman reported adsorption of surfactant molecules on a metal surface [2], but only after 40 years SAMs showed their real potential with the discovery of the first gold-alkylthiolate monolayer by Nuzzo and Allara [3]. Electrochemical Impedance Spectroscopy (EIS) and cyclic voltammetry (CV) are suitable techniques for monitoring SAM properties. Methodology is based on comparison of the results obtained with the unmodified and modified electrode [4]. In this work we present results which can be employed for albumine sensor development. EIS measurements were done, for a bare gold electrode, in three- electrode electrochemical cell (W – quartz crystal gold electrode, A – Pt wire, R – Ag/AgCl) at 0 V vs. Ag/AgCl. The frequency range was between 65 kHz and 1 Hz. Data points were collected at intervals of 5 points per dacade on a logarithmic scale, under excitation of sinusoidal wave with amplitude of ± ; 5 mV. The impedance spectra can be adequately fitted to an equivalent circuit involving solution resistance in series with a constant phase element. The buffer concentration was varied from 2 mM to 250 mM to determine which gives the best agreement with ideal behaviour (Helmholtz ideal capacitor model, where the phase angle at 1 Hz is 90°). Self-assembled monolayer was prepared on a gold electrode, and the layer growth was investigated by impedance spectroscopy with same measurement parameters as for the bare electrode. The modification of the electrode was done in three steps (a) preparation of cysteamine self-assembled monolayer, Au-CA, (b) activation of Au-CA by glutaraldehyde, Au-CA-GA, (c) functionalization of Au-CA-GA by nickel complex of nitrilotriacetic acid (Ni2+-NTA). (Fig. 1.) Fig. 1: Reaction steps in the preparation of three- layered SAM. After preparation and characterization, the SAM was exposed to the solution of albumine and resulting impedance spectra indicated that albumine molecules got attached to the layer. In the next step we plan to use QCM system (quartz crystal microbalance) for further validation of efficiency and performance of the developed sensor. [1] A. Ulman, Chem. Rev. 96, (1996), 1533. [2] W. C. Bigelow, D. L. Pickett, W. A. Zisman, J. Colloid Interface Sci. 1, (1946) 513. [3] R .G. Nuzzo, D. L. Allara, J. Am. Chem. Soc. 105, (1983), 4481. [4] S. Campuzano, M. Pedrero, C. Montemayor, E. Fatás, J. M. Pingarroón, J. Electroanal. Chem. 586, (2006), 112.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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