Stereomodulating effect of remote groups on the NADH-mimetic reduction of alkyl aroylformates with 1,4-dihydronicotinamide-β-lactam amides

Conformationally restricted NADH peptidomimetics 4a-e, characterized by the presence of a (1,4-dihydronicotinamide)-(β-lactam) moiety, have been synthesized and used to study the Mg²⁺ cation-promoted asymmetric reduction of alkyl aroylformates in acetonitrile. Increasing the bulkiness of peripheral substituents at the nitrogen atom of the β-lactam ring, at the 1,4-dihydronicotinamide moiety, or at the aroylformate ester group, was found to cause weak but clearly detectable variations of the enantiomeric excess of the reaction. A rational for these observations was consistent with a chelated NADH/Mg²⁺/ArCOCO₂R³ ternary complex model, according to DFT calculations computed at a B3LYP/6-31G^∗ theory level.     

Comparative Studies on Electrocatalytic Activities of Chemically Reduced Graphene Oxide and Electrochemically Reduced Graphene Oxide Noncovalently Functionalized with Poly(methylene blue)

This study compares the electrocatalytic activities of chemically reduced graphene oxide (crGO) and electrochemically reduced graphene oxide (erGO), which are both noncovalently functionalized with a polyaromatic dye, poly(methylene blue) (polyMB), toward the oxidation of β‐nicotinamide adenine dinucleotide (NADH). PolyMB‐crGO and polyMB‐erGO composites were obtained via electropolymerization of methylene blue on crGO and GO modified glassy carbon (GC) electrodes, respectively. Cyclic voltammetry (CV) results indicate that these two types of integrated electrodes reveal different electrocatalytic activities. PolyMB‐crGO integrated electrode possesses lower catalytic oxidation potential, suggesting higher catalytic activity. The present study is helpful for the understanding and screening of graphene‐based advanced carbon nanomaterials for potential electrochemical applications.     

Theoretical Study of One-electron Redox Potentials of Some NADH Model Compounds

Several 1‐benzyl‐1,4‐dihydronicotinamide derivatives, which are important NADH model compounds were studied theoretically in acetonitrile. The performances of various DFT methods including B3LYP, B1B95, B3PW91, MPW1B95, MPWKCIS, and M06 were tested to calculate the redox potentials. The first theoretical protocol to predict the redox potentials of these derivatives is B1B95, whose reliability has been tested against almost all the available experimental data. Strikingly, the mean absolute derivations (MAD) and root mean square (RMS) error of the current theoretical model equal 0.015 and 0.017, respectively. By using this method, the important thermodynamic properties of BNAHs were investigated and the mechanisms of hydride transfer progress were explained. Besides, para‐substituents that have a big effect on these redox potentials of BNAH were systematically studied and carefully demonstrated.     

Direct Modification of a Glassy Carbon Electrode with Toluidine Blue Diazonium Salt: Application to NADH Determination and Biosensing of Ethanol

We describe here the covalent modification of a glassy carbon electrode with toluidine blue (TB) diazonium salt, which is generated in situ from the reaction between the aromatic amino phenyl group of TB and sodium nitrite. TB is attached directly to the electrode surface without any cross‐linking agent or complex matrices. The resulting TB films exhibit excellent electrocatalytic behavior toward NADH oxidation. Low potential detection of NADH is performed at 0.15 V vs. Ag/AgCl. Furthermore, an ethanol biosensor is developed using the TB modified electrode and alcohol dehydrogenase. The great stability and reusability, excellent electrochemical reversibility, technically simple preparation and short preparation time make this method suitable for low‐cost bioelectronical devices.     

A Simple and Effective Way to Integrate Nile Blue Covalently onto Functionalized SWCNTs Modified GC Electrodes for Sensitive and Selective Electroanalysis of NADH

A simple and new way to assemble Nile blue (NB) covalently onto the surface of functionalized single‐walled carbon nanotubes (f‐SWCNTs) modified glassy carbon (GC) electrode (NB/f‐SWCNTs/GC electrode) was described. The NB/f‐SWCNTs/GC electrode catalyzes effectively the oxidation of NADH with a remarkably decreased overpotential (ca. 700 mV) compared with that at the bare GC. The reaction was found to obey a so‐called Michaelis–Menten kinetics and the related kinetic parameters were determined. This modified electrode possesses promising characteristics as NADH sensor; a wide linear dynamic range of 0.2 to 200 µM, low detection limit of 0.18 µM, fast response time (1–2 s), high sensitivity (24 µA cm⁻² mM⁻¹), anti‐interference ability and anti‐fouling.     

Electrochemical Polymerization of Azure Blue II and Its Electrocatalytic Activity toward NADH Oxidation

IntroductionOver 30 0dehydrogenasesareknowntobedependentonthenicotiamideadeninedinucleotidecoenzymeinitsreduced (NADH )andoxidized (NAD+)forms ,andamonitoringofenzymaticallygeneratedNADHisthebasisforthedevelopmentofbiosensorsfortheselecteddehydro genase .Hence ,thedetectionofthiscoenzymeisimpor tantinbothpracticalanalysisandbiochemicalsynthesis .ThereportedoverpotentialforoxidationofNADHatpH7 0isabout 1 1Vatcarbonand 1 3Vatplatinumelec trodes .1,2 Itisgenerallyacceptedthatthedirecto…     

Effects of Carbon Nanotube Paper Properties on Enzymatic Bioanodes

Carbon papers are frequent current collectors in fuel cells, but recently carbon nanotube papers have been introduced as new types of carbon paper. They have varying thickness, surface area, density, gas permeability, and conductivity. This paper studies the effect of these properties on electrochemical performance. Electropolymerizing methylene green on each carbon nanotube papers was performed to study the papers’ ability to oxidize NADH. Secondly, glucose bioanodes were formed with carbon nanotube papers to study glucose bioelectrocatalysis. The optimal carbon nanotube paper had a high surface area, low gas permeability, and low sheet resistance. Our results showed a greater than three‐fold increase in sensitivity over commercially available Toray carbon paper.     

PAA-supported Hantzsch 1,4-dihydropyridine ester: an efficient catalyst for the hydrogenation of α,β-epoxy ketones

A new type of water-soluble polymer-supported NADH co-enzyme model-PAA (polyacrylic acid)-supported Hantzsch 1,4-dihydropyridine ester (PAA–HEH) was designed and synthesized. Catalytic amount of the supported reagent was used in the hydrogenation of α,β-epoxy ketones to the corresponding β-hydroxy ketones and showed great catalytic efficiency in the reduction reaction. This PAA–HEH was an optimal potential for recycling use.