Electrocatalytic effect towards NADH induced by HiPco single-walled carbon nanotubes covalently functionalized by ferroc
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Electrocatalytic effect towards NADH induced by HiPco single-walled carbon nanotubes covalently functionalized by ferrocene derivatives Naoual Allali1, 2,5, Veronika Urbanova1, Mathieu Etienne1, Martine Mallet1, Xavier Devaux,3 Brigitte Vigolo4, Yves Fort2, Alain Walcarius1, Maxime Noël5, Edward McRae4, Alexander V. Soldatov5, Manuel Dossot1,*, Victor Mamane2. 1. Laboratoire de Chimie Physique et Microbiologie pour l’Environnement, UMR 7564 CNRSUniversité de Lorraine, F-54602 Villers-les-Nancy, France. 2. Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes, UMR 7565 CNRS-Université de Lorraine, F-54506 Vandoeuvre-les-Nancy, France. 3. Département P2M, Institut Jean Lamour, UMR 7198 CNRS-Université de Lorraine, Ecole des Mines, F-54042 Nancy, France. 4. Département CP2S, Institut Jean Lamour UMR 7198 CNRS-Université de Lorraine, F-54506 Vandoeuvre-les-Nancy, France. 5. Department of Engineering Sciences and Mathematics, Lulea University of Technology, SE97187 Lulea, Sweden. ABSTRACT The present work reports the covalent functionalization of single-walled carbon nanotubes (SWCNTs) by ferrocene derivatives with polyethyleneglycol linkers. A very clean initial sample was chosen to avoid any residual catalyst and carbon impurities. Functionalized SWCNTs (f-CNTs) are deposited on the surface of a glassy carbon electrode (GCE) and this modified electrode is used for oxidizing the cofactor NADH (dihydronicotinamide adenine dinucleotide) in the presence of diaphorase. A clear electrocatalytic effect is evidenced, which can only be attributed to the f-CNTs. INTRODUCTION For electrochemical applications, several properties render carbon nanotubes (CNTs) very attractive including the diameter-dependent metallic or semi-conducting behavior, the high aspect ratio and the high specific surface area [1-3]. Chemical functionalization of CNTs is often used to attach electroactive molecules that can play the role of an electron shuttle (also known as redox mediators). Mediators react with the redox center of a protein or can be used to electrochemically detect the NADH cofactor. They can be covalently grafted or simply sorbed on the CNT surface [3]. If the envisaged applications concern biosensors or bioreactors, it is preferable that the mediator be covalently linked to the CNT surface to avoid any diffusion of the molecule in the analyzed medium or the reactor solution. Covalent functionalization therefore increases the lifetime of the electrochemical device but the functionalization step has to be sufficiently controlled to avoid degradation of the initial electronic properties of the CNTs. Many pioneering studies using CNTs for electrochemical devices employed multi-walled CNTs (MWCNTs) [1-3]. These are indeed cheaper and produced in higher quantities than SWCNTs; the chemistry on MWCNTs has been well explored and many reactions have been used to introduce oxidized defects on their side-walls [4,5]. This strategy allows increasing the interaction with polar solvents and notably water, and it seems that oxidi
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