Naslov
Electrocatalytic Regeneration of NADH on a Ruthenium Nano-modified Glassy Carbon Surface

Autori
Omanović, Saša ; Damian, Alexis ; Azem, Amir ; Man, Felise

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Skup
1st ECHEM Meeting, 2005.

Mjesto i datum
Venecija, Italija, 15.05.2005. - 20.05.2005

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Ru(GC) catalyst; NADH electrocatalytic regeneration; Kinetic and Thermodynamic parameters.

Sažetak
Nicotinamide adenine dinucleotide NAD(H) is a cofactor that is involved in a large number of biochemical processes. It plays the role of electron and hydrogen shuttle in most of the biochemical reactions catalyzed by redox enzymes. In its reduced and enzymatically active form (1, 4-NADH), the molecule transfers two electrons and a proton to a substrate in the presence of a suitable enzyme to form NAD^+. The high cost of NADH is one of the major limitations for its large-scale industrial use. Therefore, it is of great importance to develop methods that could regenerate NADH in-situ and allow its catalytic quantities to be used. Electrochemistry offers a number of advantages compared to (bio)chemical processes used for NADH regeneration. However, the use of unmodified metal electrode surfaces results in the formation of large quantities of an inactive dimer (NAD_2), rather than the active form, 1, 4-NADH. The research in this area done recently in our laboratory has focused on the development of direct and enzyme-mediated electrode systems for NADH regeneration [1, 2]. The present work discusses the results on the use of a ruthenium nano-modified glassy carbon electrode (RuGC) for the direct electrochemical reduction of NAD+ (i.e. regeneration of NADH). These results are compared to results of the NADH regeneration using an Au electrode, and also to results obtained using an electro-enzymatic approach. The purpose of the study has also been to get better insight into fundamental electro(chemical) and physical processes that are involved in the reduction of NAD^+ at a solid surface, which will serve as a basis for the further design of multicomponent nano-patterned catalysts for the regeneration of 1, 4-NADH. The study has shown that the modification of GC by a sub-monolayer of Ru can provide an electrode surface capable of reducing NAD^+ directly to active 1, 4-NADH (96% yield), avoiding the formation of the inactive dimer. The reaction is highly irreversible, and occurs at high cathodic overpotentials, where the reaction rate is controlled by the surface diffusion of electroactive species. It has been postulated that Ru sites (nano-islands) have a bifunctional role, serving as both proton-providing sites, and as a physical barrier for dimerization of NAD-free radicals. A set of kinetic and thermodynamic parameters has been calculated and verified independently using various experimental techniques. References: (1) Azem, A. ; Man, F. ; Omanovic, S. ; J.Mol.Catal.A: Chemical 2004, 219, 283. (2) Man, F. ; Omanovic, S. ; J.Electroanal.Chem. 2004, 568C, 301.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Kemijsko inženjerstvo

POVEZANOST RADA