Ca2+ enhanced catalytic NADH oxidation: a coupled 31P-NMR and electrochemistry study

NADH electrooxidation using carbon paste electrodes modified with nitro-fluorenone derivatives immobilized on zirconium phosphate

“…In earlier reports on the electrocatalytic behavior of nitrofluorenones adsorbed on glassy carbon a 5-fold increase in k obs½NADH¼0 was found for 2,5,7-trinitro-9-fluorenone-4-carboxylic acid by the addition of Ca 2þ [28]. The enhanced rate constant is due to the added cations that play the role of a bridging unit between the carboxyl group of the mediator and the phosphate groups of NADH [62]. This is supported by the fact that the K M -value in the presence of Ca 2þ [28,52] or Mg 2þ [61] is decreased reflecting an increased affinity for NADH to bind to the mediator.…”

Tailored Mesostructuring and Biofunctionalization of Gold for Increased Electroactivity

“…Both the carboxyl group of the TNF and the phosphate groups of the NADH can form a complex with Ca 2+ , which therefore acts as an electrostatic bridge. [30][31][32] The NADH adsorbed at the surface can be detected in the first cycle by cyclic voltammetry (Figure 4 a). As expected, the oxidation current increases linearly with the number of pore layers.…”

Bioelectrocatalysis with modified highly ordered macroporous electrodes

“…Therefore we tried in the next step to take advantage of the known interaction between mediator, calcium ions and NADH [25,29,30] to adsorb a layer of coenzyme onto the pore walls. Successive dipping of the mediator modified electrode in a concentrated CaCl 2 solution and, after rinsing, in a solution of NADH leads to the deposition of a specific amount of coenzyme.…”

“…The internal surface of the macroporous electrode is in the first step modified with a monolayer of a nitrofluorenone derivative which plays the role of the redox mediator [16]. In a second step a monolayer of calcium cations is immobilized at the interface, serving as a bridge between the redox mediator and the subsequently adsorbed coenzyme [24,25]. In the last step, the enzyme is adsorbed, using the intrinsic affinity of the NAD + monolayer for dehydrogenase [21], and the resulting biosensor is stabilized by a Nafion Ò membrane (Scheme 1B).…”