Talanta 64 (2004) 1151–1159 (Bio)sensors based on manganese dioxide-modified carbon substrates: retrospections, further improvements and applications  Negussie W. Beyene a,1 , Petr Kotzian b , Klemens Schachl a , Hailemichael Alemu c , Emir Turkuši´ c d , Amira ˇ Copra d , Helmut Moderegger a , Ivan Švancara b , Karel Vytˇ ras b,∗ , Kurt Kalcher a,2 a Institute of Chemistry-Analytical Chemistry, Karl-Franzens University, A-8010 Graz, Austria b Department of Analytical Chemistry, University of Pardubice, CZ-532 10 Pardubice, Czech Republic c Department of Chemistry, National University of Lesotho, P.O. Roma 180, Lesotho d Department of Chemistry, University of Sarajevo, 71000 Sarajevo, Bosnia and Herzegovina Received 26 January 2004; received in revised form 29 March 2004; accepted 29 March 2004 Available online 28 July 2004 Abstract An overview is presented which summarizes our accomplishment in the development of sensors and biosensors based on heterogenous carbon electrodes modified with manganese dioxide. Brief account of each sensor and biosensor has been given and example of real sample applications provided where appropriate. © 2004 Elsevier B.V. All rights reserved. Keywords: Carbon paste electrodes; Screen-printed electrodes; Biosensors; Modification; Electroanalysis 1. Introduction Heterogeneous carbon materials have been used as elec- trochemical sensors and biosensors because of their avail- ability in a variety of forms, low cost, broad exploitable potential window, low background current, chemical inert- ness, ease of chemical derivatization and modification, and suitability for various applications [1,2]. Among the various carbon-based electrodes available for the development of electrochemical sensors and biosensors, carbon paste elec- trodes (CPEs) and screen-printed carbon electrodes (SPCEs) have got widespread popularity due to their ease of prepa- ration and modification, ease of surface renewal and repro-  Presented at the 12th International Conference on Flow Injection Analysis, Merida (Venezuela), 7–13 December 2003. ∗ Corresponding author. Tel.: +420 466 037 712; fax: +420 466 037 068. E-mail addresses: karel.vytras@upce.cz (K. Vytˇ ras), kurt.kalcher@uni-graz.at (K. Kalcher). 1 Current address: Department of Chemistry, University of Pretoria, 0002 Pretoria, South Africa. 2 Tel.: +43 316 380 5310; fax: +43 316 380 9845. ducibility in case of CPEs, and mass production of highly reproducible electrodes in case of SPCEs [2–4]. One of the analytes detected at CPEs and SPCEs is hydro- gen peroxide because of its environmental, biological and industrial importance. For this purpose, amperometric and voltammetric methods have been used. However, its direct oxidation or reduction at bare electrodes causes a problem in analytical applications because of the high overvoltage re- quired. These phenomena can be controlled by deliberately attaching chemical reagents to the electrode surface so that manipulating the nature of the surface is possible. Hence, the name chemically modified electrodes was coined [5–8]. Heterogeneous carbon electrodes were among the first to be chemically modified. Modified electrodes are appreciated for their main advan- tages such as, reduction of the H 2 O 2 overvoltage and hence diminishing the interference from other species by promo- tion of electron transfer reactions which may increase the selectivity, specificity and reproducibility of the electrode surface, and improving the detection limit [1–8]. These elec- trodes can be prepared by chemisorption, covalent bond for- mation between specific functional group on the electrode surface and the reagent, coating the electrode with polymeric 0039-9140/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2004.03.068