Colloids and Surfaces B: Biointerfaces 110 (2013) 270–274 Contents lists available at SciVerse ScienceDirect Colloids and Surfaces B: Biointerfaces jou rn al hom epage: www.elsevier.com/locate/colsurfb Cibacron Blue F3GA modified disposable pencil graphite electrode for the investigation of affinity binding to bovine serum albumin Filiz Kuralay a,∗ , Erkut Yılmaz b , Lokman Uzun b,∗∗ , Adil Denizli b a Department of Chemistry, Faculty of Arts and Sciences, Ordu University, 52200 Ordu, Turkey b Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara, Turkey a r t i c l e i n f o Article history: Received 8 October 2012 Received in revised form 15 April 2013 Accepted 22 April 2013 Available online 28 April 2013 Keywords: Cibacron Blue F3GA Albumin Dye–protein interaction Pencil graphite electrode Cyclic voltammetry Electrochemical impedance spectroscopy a b s t r a c t In this work, Cibacron Blue F3GA (CB) modified pencil graphite electrodes (PGEs) were prepared and their affinities to bovine serum albumin were investigated. Preparation of the PGEs was performed using cyclic voltammetry (CV) and passive adsorption techniques. Improved electrochemical results were obtained with the PGEs prepared by CV technique compared to the PGEs prepared by passive adsorption technique. In order to obtain more sensitive results number of scans used in CV technique and the effect of con- centration of CB were studied. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS) were used for the characterization of modified electrodes. The modified PGEs were then used for the electrochemical monitoring of affinity interaction between CB and bovine serum albumin. The effect of BSA concentration and interfering species (tryptophan, glucose and immunoglobulin G) on the response of the electrode were examined. The aim of this study was to prepare an easy, fast, stable and cheap modified electrode for the investigation of the well-known affinity of CB to serum albumin. The electrochemistry can provide alternative routes for dye–protein interaction instead of using classical time-consuming methods. © 2013 Published by Elsevier B.V. 1. Introduction Triazine-based dye molecules attracted great attention in the field of protein affinity studies [1–5]. They have several advan- tages to natural counterparts for specific affinity chromatography [6,7]. They are able to bind a variety of proteins based on highly specific molecular recognition in a reversible manner [8–11]. Triazine-based dyes are commercially available and cheap. The immobilization of these dyes on surfaces is also very easy [6,12]. Although these dye molecules are synthetic in nature, they are classified as affinity ligands due to their interaction with the active sites of proteins by mimicking the structure of the cofactors, substrates, or binding agents for those proteins [2]. A number of textile dyes, known as reactive dyes, can be used for protein related studies. Most of these reactive dyes contain a chromophore (either azo dyes, antraquinone, or phathalocya- nine) linked to a reactive group (often a mono- or dichlorotriazine ring). The synergic effect of combination of secondary forces such as electrostatic, hydrophobic and hydrogen binding plays an ∗ Corresponding author. Tel.: +90 452 2345010x1680; fax: +90 452 2339149. ∗∗ Corresponding author. Tel.: +90 312 29767963; fax: +90 312 2996084. E-mail addresses: kuralay.filiz@gmail.com (F. Kuralay), lokman@hacettepe.edu.tr (L. Uzun). important role in the interaction of these dyes with biomolecules [2,7]. Cibacron Blue F3GA (CB) is one of the most commonly used dye ligands for protein affinity studies [13]. It is a derivative of monochlorotriazine dye (antraquinone textile dye) which contains three titrable acidic sulfonate and four basic primary and secondary aromatic amine groups and it is also commercially important in the dyeing of cellulose fibers [12,14,15]. Its affinity to serum albumin is studied in details and reported in the literature [16–19]. It is known that CB interacts specifically and reversibly with albumin by the combination of hydrophobic, hydrogen bonding and electrostatic interactions [7]. However, the number of studies including elec- trochemistry of CB is very limited [6,15,20]. Nowadays, there is an increasing demand in electrochemical sensing strategies due to the fact that electrochemistry provides several advantages such as fast response, easy, stable, controllable and simple preparation of the modified surfaces [21]. Bovine serum albumin (BSA) is the most abundant protein. It plays an important role in the binding, transportation and depo- sition of variety of endogenous and exogenous ligands in blood. It is widely used as a blocking agent to reduce the non-specific protein–protein or protein–surface interactions. BSA can be used as a model protein applied in enzyme-linked immunosorbent assay because of its good stability and low cost. Thus, the development of detection systems for BSA holds great interest in various fields [22–24]. 0927-7765/$ – see front matter © 2013 Published by Elsevier B.V. http://dx.doi.org/10.1016/j.colsurfb.2013.04.024