Determination of reduced nicotinamide adenine dinucleotide based on immobilization of tris(2,2′-bipyridyl) ruthenium(II) in multiwall carbon nanotubes/Nafion composite membrane

An electrochemiluminescence (ECL) method for reduced nicotinamide adenine dinucleotide (NADH) was proposed by immobilizing tris(2,2'-bipyridyl) ruthenium(II) (Ru(bpy)(3)(2+)) in multiwall carbon nanotubes (MWCNTs)/Nafion composite membrane that was formed on glassy carbon electrode surface. The electrochemical and ECL behaviors of the immobilized Ru(bpy)(3)(2+) were investigated. The cyclic votammogram of the modified electrode in pH 7.0 phosphate buffer solution showed a couple of redox peaks at +1190 and +1060 mV at 100 mV/s. The composite film had a more open structure and a large surface area allowing faster diffusion of Ru(bpy)(3)(2+) . The presence of MWCNTs resulted in the improved ECL sensitivity and longer-term stability of the modified electrode. The modified electrode showed a linear response to NADH in the concentration range of 1.0x10(-6) to 1.6x10(-5) M with a detection limit of 8.2x10(-7) M.