Electrogenerated chemiluminese ethanol biosensor based on carbon nanotube-titania-nafion composite film

Mesoporous titania-Nafion composite doped with carbon nanotube (CNT) has been used for the immobilization of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)) and alcohol dehydrogenase on an electrode surface to yield a highly sensitive and stable electrogenerated chemiluminescence (ECL) ethanol biosensor. The presence of CNT in the composite film increases not only the sensitivity of the ECL biosensor but also the long-term stability of the biosensor. The present biosensor responds linearly to ethanol in the wide concentration ranges from 1.0 x 10(-5) M to 1.0 x 10(-1) M with a detection limit of 5.0 x 10(-6) M (S/N= 3). The present ECL ethanol biosensor exhibited higher ECL response compared to that obtained with the ECL biosensor based on the corresponding composite without CNT. The present CNT-based ECL biosensor showed good long-term stability with 75% of its initial activity retained after 2 weeks of storage in 50 mM phosphate buffer at pH 7.0.