Poly (4-methoxyphenol) film as a galactose-sensing material Ergun Ekinci * , Aziz Pas ßahan Department of Chemistry, Faculty of Arts and Sciences, _ I n€on€u University, 44069 Malatya, Turkey Received 16 March 2004; received in revised form 13 April 2004; accepted 21 April 2004 Available online 15 June 2004 Abstract Poly (4-methoxyphenol)-galactose oxidase biosensor for galactose is reported. This amperometric biosensor was prepared in a one-step procedure by electrochemical polymerization of the relevant monomer in the presence of galactose oxidase on Pt electrode surface in a KCl solution at potential of 0.6 V vs. Ag/AgCl. From the steady-state amperometric responses to galactose of the resulting polymeric biosensor, its sensor characteristics such as feasibility of preparation, linear range, response time, selectivity and stability were evaluated. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: Poly (4-methoxyphenol) film; Enzyme electrode; Galactose biosensor 1. Introduction Galactose level in human blood is important because of its well-known importance in clinical chemistry such as galactosemia and galactose intolerance [1]. Up to now, various methodologies have been developed for galactose measurement. Among these, in recent years, some polymeric biosensors based on galactose oxidase have been used [1–5]. On the other hand, electropolymerization offers a simple, flexible and readily controlled method for the simultaneously enzyme immobilization (in a one-step procedure). By means of this technique, it has been demonstrated that some conducting or non-conducting polymeric films such as polypyrroles [6–10], polyindole [11] polyaminophenols [12,13], polyphenylenediamines [14,15], polyaniline [16], poly (o-toluidine) [17] and polythiophene [18] could be used to immobilize glucose oxidase in the glucose biosensor construction. Also, in a previous work, we have reported that de- tailed studies of poly (4-methoxyphenol) film as a sensor material in the construction of amperometric glucose biosensor [19]. The electropolymerization of phenol and its derivatives is known to produce thin, hydrophobic and insulating films at the electrode surface. These films are produced by ortho or para coupling of phenolate radicals generated at the electrode surface leading to the deposition of a poly (phenylene oxide) film [20,21]. In this work presented, we wished to prepare a galactose-sensing sensor. For this reason, galactose oxidase has been immobilized simultaneously within poly (4-methoxyphenol) film during polymer growth (in a one-step procedure). Then, amperometric sensor characteristics of the resulting poly (4-methoxyphe- nol)––galactose oxidase biosensor have been examined. 2. Experimental 2.1. Materials 4-methoxyphenol was supplied from Merck (Darmstad, Germany) and used as received. Galactose oxidase (GalOx) (E.C.1.1.3.9) from Dactylium den- droxides was obtained from Sigma Chemical Company. D(+) Galactose was supplied from Acros Organics. All the other chemicals such as KCl, ascorbic acid, oxalic acid, 4-acetoamidophenol, lactose, sucrose and urea were of analytical grade and supplied either by Sigma Chemical Company or E. Merck. Amperometric mea- surements were performed in a PBS (phosphate buffer * Corresponding author. Tel.: +90-422-341-0010; fax: +90- 422-341-0037. E-mail address: eekinci@inonu.edu.tr (E. Ekinci). 0014-3057/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2004.04.020 European Polymer Journal 40 (2004) 1605–1608 www.elsevier.com/locate/europolj EUROPEAN POLYMER JOURNAL