Talanta 52 (2000) 791–799 Development of biosensors based on hexacyanoferrates Ivanildo Luiz de Mattos *, Lo Gorton a , Thomas Laurell b , A. Malinauskas c , Arkady A. Karyakin d a Department of Analytical Chemistry, Lund Uniersity, PO Box 124, SE-221 00 Lund, Sweden b Department of Electrical Measurements, Lund Uniersity, Lund, Sweden c Institute of Chemistry, Vilnius, Lithuania d Department of Chemistry, MVL Moscow State Uniersity, Moscow, Russia Received 13 December 1999; received in revised form 5 April 2000; accepted 8 April 2000 Abstract Ferric and copper hexacyanoferrates (PB and CuHCF, respectively) were electrodeposited on glassy carbon electrodes providing a suitable catalytic surface for the amperometric detection of hydrogen peroxide. Additionally glucose oxidase was immobilized on top of these electrodes to form glucose biosensors. The biosensors were made by casting glucose oxidase – Nafion layers onto the surface of the modified electrodes. The operational stability of the films and the biosensors were evaluated by injecting a standard solution (5 MH 2 O 2 for PB, 5 mM H 2 O 2 for CuHCF and 2.5 mM glucose for both) over 5–10 h in a flow-injection system with the electrodes polarized at -50 (PB) and -200 mV (CuHCF) versus Ag/AgCl, respectively. The glucose biosensors demonstrated suitability for glucose determination: 0.0–2.5 mM (R 2 =0.9977) for PB and 0.0–10 mM (R 2 =0.9927) for CuHCF, respectively. The visualization of the redox catalyst modifiers (PB and CuHCF films) was presented by scanning electron micrographs. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Prussian Blue; Copper hexacyanoferrate; Hydrogen peroxide; Biosensor www.elsevier.com/locate/talanta Transition metal hexacyanoferrates have at- tracted widespread attention due to their useful characteristics for creating well-defined electroac- tive films on electrodes [1–3]. They are known as useful electrocatalysts in selected electrochemical processes and are suitable as electrode modifiers to make amperometric sensors for the determina- tion of solution components [2 – 5]. The formation and properties of transition metal hexacyanofer- rate films at modified electrodes have been investi- gated by numerous workers [6–15] and the most intensively examined compound has been {Fe 4 [Fe(CN) 6 ] 3 ·x H 2 O} known as Prussian Blue [2,5,16,17]. However, the use of electrodes modified with copper hexacyanoferrate films has demonstrated the importance with the develop- ment of diverse applications such as selective elec- trode for cations [18], microsensors [19] and for the determination of sulfhydryl compounds [20] * Corresponding author. Present address: Departamento de Quı ´mica, Faculdade de Cie ˆncias–UNESP, PO Box 473, 17033-360 Bauru SP, Brazil. E-mail address: ilmattos@hotmail.com (I.L. de Mattos). 0039-9140/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII:S0039-9140(00)00409-4