A simple derivatization of multiwalled carbon nanotubes with nitroaromatics in aqueous media: Modification with nitroso/hydroxylamine groups

We report that GCE modified with MWCNTs can be derivatized by the nitroaromatic drug nitrendipine (NTD) ((RS)-ethyl methyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate) simply by dipping the electrode in a solution of 0.1 M Britton-Robinson buffer containing 0.1 mM NTD (pH 2) for 4 min at open circuit. The derivatized electrode is thus reduced, producing the corresponding hydroxylamine derivative-modified electrode, which can be further oxidized to the nitroso derivative. A stable nitroso/hydroxylamine derivative couple appears if the modified electrode is conveniently cycled. With proper selection of the adequate potential, the derivatized electrode can be modified as nitroso or hydroxylamine derivatives.