Graphite Electrode Modified with a New Phenothiazine Derivative and with Carbon Nanotubes for NADH Electrocatalytic Oxidation

D. Gligor, C. Varodi and L. M. Muresan

Abstract
The electrochemical behavior of a modified electrode obtained by immobilization of single-walled carbon nanotubes onto a graphite electrode modified with a new phenothiazine derivative, bis-phenothiazin-3-yl methane (BPhM), G/BPhM-CNT, has been evaluated and compared with BPhM adsorbed on graphite electrode (G/BPhM). The G/BPhM-CNT electrode presents improved performances for NADH electrocatalytic oxidation in comparison with G/BPhM electrode, expressed by: (i) a significant increase of electrocatalytic rate constant (kobs,[NADH] = 0) for NADH oxidation (856.32 L mol–1 s–1 for G/BPhM-CNT and 51.63 L mol–1 s–1 for G/BPhM, in phosphate buffer, pH 7); (ii) the obtained amperometric sensors for NADH detection present increase sensitivity (S = 6.9 mA L mol–1 for G/BPhM-CNT and S = 0.55 mA L mol–1 for G/BPhM, pH 7).

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Keywords
Phenothiazine derivative, Carbon nanotubes, NADH