Analisis

Journal of Molecular Catalysis B: Enzymatic 72 (2011) 282–288

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Journal of Molecular Catalysis B: Enzymatic
journal homepage: www.elsevier.com/locate/molcatb

Amperometric xanthine biosensors based on electrodeposition of platinum on polyvinylferrocenium coated Pt electrode
Salih Zeki Bas a,∗ , Handan Gülce b , Salih Yıldız a ¸
a b

Departmentof Chemistry, Selcuk University, Konya 42075, Turkey ¸ Department of Chemical Engineering, Selcuk University, Konya 42075, Turkey ¸

a r t i c l e

i n f o

a b s t r a c t
Novel xanthine biosensors were successfully fabricated by immobilizing xanthine oxidase on polyvinylferrocenium perchlorate matrix (PVF+ ClO4 − ) and platinum electrodeposited polyvinylferrocenium perchlorate matrix.PVF+ ClO4 − film was coated on Pt electrode at +0.7 V vs. Ag/AgCl by electrooxidation of polyvinylferrocene (PVF). Platinum nanoparticles were deposited on PVF+ ClO4 − electrode by electrochemical deposition in 2.0 mM H2 PtCl6 solution at −0.2 V. Xanthine oxidase was incorporated into the polymer matrix via ion exchange process by immersing modified Pt electrodes in the enzyme solution. Theamperometric responses of the biosensors were measured via monitoring oxidation current of hydrogen peroxide at +0.5 V. Under the optimal conditions, the linear ranges of xanthine detection were determined as 1.73 × 10−3 –1.74 mM for PVF+ XO− and 0.43 × 10−3 –2.84 mM for PVF+ XO− /Pt. The detection limits of xanthine were 5.20 × 10−4 mM for PVF+ XO− and 1.30 × 10−4 mM for PVF+ XO− /Pt. Moreover, theeffects of applied potential, electrodeposition potential, H2 PtCl6 concentration, amount of electrodeposited Pt nanoparticles, thickness of polymeric film, temperature, immobilization time, xanthine and xanthine oxidase concentrations on the response currents of the biosensors were investigated in detail. The effects of interferents, the operational and storage stabilities of biosensors and theapplicabilities to drug samples of the biosensors analysis were also evaluated. © 2011 Elsevier B.V. All rights reserved.

Article history: Received 8 April 2011 Received in revised form 24 June 2011 Accepted 24 June 2011 Available online 2 July 2011 Keywords: Xanthine detection Xanthine oxidase Platinum electrodeposition Amperometric biosensor Polyvinylferrocenium

1. Introduction Xanthineoxidase, controlling a part of purine metabolism and catalyzing the oxidation of hypoxanthine to xanthine and of xanthine to uric acid, plays an important role in human and mammalian life. Xanthine oxidase is a flavoprotein that contains molybdenum, iron and labile sulfur. The enzymatic reaction, occurs between substrate and xanthine oxidase, is based on a mechanism involving nucleophilic attack onsubstrate by the Mo–OH group at the active site of xanthine oxidase [1]. The levels of xanthine oxidase in clinical disorders related to purine metabolism are symptoms of several diseases such as gout, xanthinuria and hyperuricaemia [2]. In ischemia–reperfusion injury, xanthine oxidase is proposed as a source in the formation of superoxide and hydrogen peroxide in ischemic tissues [3]. For thediagnosis and the treatment of the diseases, the amount of xanthine in the blood and the tissue samples should be easily analyzed. The determination of xanthine is also used in the food industries for the quality control of fish products. Hence, the quantity of xanthine is of clinical and industrial importance [4,5].

∗ Corresponding author. Tel.: +90 332 2233877. E-mail address:salihzekibas@gmail.com (S.Z. Bas). ¸ 1381-1177/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.molcatb.2011.06.017

In the literature, several analytical methods such as electrophoresis [6,7], HPLC [8,9], amperometric and voltametric methods [10,11] have been reported for quantitative determination of xanthine. In recent years, electrochemical methods have been frequently used for the...