NADH Electrooxidation Using Bis(1,10-phenanthroline-5,6-dione) (2,2'-bipyridine)ruthenium(II)-Exchanged Zirconium Phosphate Modified Carbon Paste Electrodes.

We present a carbon paste electrode (CPE) modified using the electron mediator bis(1,10-phenanthroline-5,6-dione) (2,2'-bipyridine)ruthenium(II) ([Ru(phend)(2)bpy](2+)) exchanged into the inorganic layered material zirconium phosphate (ZrP). X-Ray powder diffraction showed that the interlayer distance of ZrP increases upon [Ru(phend)(2)bpy](2+) intercalation from 10.3 Å to 14.2 Å. The UV-vis and IR spectroscopies results showed the characteristic peaks expected for [Ru(phend)(2)bpy](2+). The UV-vis spectrophotometric results indicate that the [Ru(phend)(2)bpy](2+) concentration inside the ZrP layers increased as a function of the loading level. The exchanged [Ru(phend)(2)bpy](2+) exhibited luminescence even at low concentration. Modified CPEs were constructed and analyzed using cyclic voltammetry. The intercalated mediator remained electroactive within the layers (E°' = -38.5 mV vs. Ag/AgCl, 3.5 M NaCl) and electrocatalysis of NADH oxidation was observed. The kinetics of the modified CPE shows a Michaelis -Menten behavior. This CPE was used for the oxidation of NADH in the presence of Bakers' yeast alcohol dehydrogenase. A calibration plot for ethanol is presented.