Β-nicotinamide Adenine Dinucleotide Research Articles

Kinetic Model for the Heterogeneous Biocatalytic Reactions Using Tethered Cofactors.

Understanding the mechanism of interfacial enzyme kinetics is critical to the development of synthetic biological systems for the production of value-added chemicals. Here, the interfacial kinetics of the catalysis of β-nicotinamide adenine dinucleotide (NAD+)-dependent enzymes acting on NAD+ tethered to the surface of silica nanoparticles (SiNPs) has been investigated using two complementary and supporting kinetic approaches: enzyme excess and reactant (NAD+) excess. Kinetic models developed for these two approaches characterize several critical reaction steps including reversible enzyme adsorption, complexation, decomplexation, and catalysis of the surface-bound enzyme/NAD+ complex. The analysis reveals a concentrating effect resulting in a very high local concentration of enzyme and cofactor on the particle surface, in which the enzyme is saturated by surface-bound NAD, facilitating a rate enhancement of enzyme/NAD+ complexation and catalysis. This resulted in high enzyme efficiency within the tethered NAD+ system compared to that of the free enzyme/NAD+ system, which increases with decreasing enzyme concentration. The role of enzyme adsorption onto solid substrates with a tethered catalyst (such as NAD+) has potential for creating highly efficient flow biocatalytic systems.

Electrochemiluminescence enzyme biosensors for ultrasensitive determination of glucose using glucose dehydrogenase immobilized on vertical silica nanochannels

Accurate determination of glucose in biological samples is of great significance for healthcare monitoring and medical diagnosis. Herein we reported an economical "signal-on" glucose electrochemiluminescence (ECL) enzyme biosensor for ultrasensitive detection of glucose based on vertically-ordered mesoporous silica films (VMSF) covalently modified with a monolayer of glucose dehydrogenase (GDH). In the presence of glucose, β-nicotinamide adenine dinucleotide sodium salt (NAD+)-dependent GDH on the surface of VMSF catalyzes the oxidation of glucose and β-nicotinamide adenine dinucleotide (NADH) reduced from NAD+ is generated concomitantly in situ. The access of NADH to underlying electrode surface is prohibited by ultrasmall nanopores, but it can act as a co-reactant to promote the ECL intensity of Ru(bpy)32+ by the free diffusion of Ru-related species, exhibiting a unique catalytic route. By recording the ECL intensity of Ru(bpy)32+ electrostatically amplified by VMSF, the present ECL enzyme biosensor allows the ultrasensitive detection of glucose substrate with a wide linear range (10 nM to 1 mM) and a rather low limit of detection (1.5 nM). Furthermore, the developed ECL enzyme biosensor is capable of anti-fouling and accurate detection of glucose in human serum and artificial sweat without tedious preprocessing, which provides a ECL enzyme sensing platform for ultrasensitive detection of a variety of substrates of interest by simply tailoring the recognition elements.

Enhanced sensitivity of a fluorometric biosensor for alcohol metabolites with an enzymatic cycling reaction

Assessing ethanol (EtOH) and acetaldehyde (AcH), metabolites of alcohol, enables more precise evaluation of alcohol metabolism. In this study, we developed a biosensor capable of concurrently measuring EtOH and AcH solutions with high sensitivity, utilizing a cycling reaction mediated by two enzymes: alcohol dehydrogenase (ADH) and alcohol oxidase (AOD). Within the cycling reaction, β-nicotinamide adenine dinucleotide (NADH, λex = 340 nm, λem = 490 nm) is oxidized when AcH is reduced to EtOH by ADH, while the EtOH produced in this reaction is oxidized by AOD, regenerating AcH. By detecting the consumption of oxygen or NADH in this reaction cycle, highly sensitive measurements of AcH and EtOH can be achieved. Initially, an AOD-ADH electrosensor was constructed to validate the feasibility of the cycling reaction by applying EtOH solution to the sensor. This electrosensor quantifies alcohol metabolites via the oxygen consumed in the cycling reaction, demonstrating a dynamic range for EtOH solution from 700 nM to 500 µM—a sensitivity two-fold greater than that achieved with the AOD membrane (1.4 µM–1 mM) alone. Subsequently, an ADH-AOD fluorosensor was developed, measuring alcohol metabolites via NADH consumption within the cycling reaction. The ADH-AOD fluorosensor demonstrated a dynamic range of 59 pM–100 µM for AcH solution, representing approximately a 1000-fold increase in sensitivity compared to the ADH membrane (70 nM–100 µM) alone. In future work, it is anticipated that utilizing this cycling reaction for the highly sensitive measurement of skin gases (EtOH and AcH) and facilitating non-invasive metabolic evaluations.

The impact of aging and oxidative stress in metabolic and nervous system disorders: programmed cell death and molecular signal transduction crosstalk.

Life expectancy is increasing throughout the world and coincides with a rise in non-communicable diseases (NCDs), especially for metabolic disease that includes diabetes mellitus (DM) and neurodegenerative disorders. The debilitating effects of metabolic disorders influence the entire body and significantly affect the nervous system impacting greater than one billion people with disability in the peripheral nervous system as well as with cognitive loss, now the seventh leading cause of death worldwide. Metabolic disorders, such as DM, and neurologic disease remain a significant challenge for the treatment and care of individuals since present therapies may limit symptoms but do not halt overall disease progression. These clinical challenges to address the interplay between metabolic and neurodegenerative disorders warrant innovative strategies that can focus upon the underlying mechanisms of aging-related disorders, oxidative stress, cell senescence, and cell death. Programmed cell death pathways that involve autophagy, apoptosis, ferroptosis, and pyroptosis can play a critical role in metabolic and neurodegenerative disorders and oversee processes that include insulin resistance, β-cell function, mitochondrial integrity, reactive oxygen species release, and inflammatory cell activation. The silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), AMP activated protein kinase (AMPK), and Wnt1 inducible signaling pathway protein 1 (WISP1) are novel targets that can oversee programmed cell death pathways tied to β-nicotinamide adenine dinucleotide (NAD+), nicotinamide, apolipoprotein E (APOE), severe acute respiratory syndrome (SARS-CoV-2) exposure with coronavirus disease 2019 (COVID-19), and trophic factors, such as erythropoietin (EPO). The pathways of programmed cell death, SIRT1, AMPK, and WISP1 offer exciting prospects for maintaining metabolic homeostasis and nervous system function that can be compromised during aging-related disorders and lead to cognitive impairment, but these pathways have dual roles in determining the ultimate fate of cells and organ systems that warrant thoughtful insight into complex autofeedback mechanisms.

The effect of epigallocatechin gallate on laying performance, egg quality, immune status, antioxidant capacity, and hepatic metabolome of laying ducks reared in high temperature condition

Epigallocatechin gallate (EGCG) is a main component in green tea extract, which possesses multiple bioactivities. The present research studied the effects of EGCG on the laying performance, egg quality, immune status, antioxidant capacity, and hepatic metabolome of Linwu laying ducks reared under high temperature. A total of 180 42-w-old healthy Linwu laying ducks were allocated into control or EGCG-treated groups. Each treatment had 6 replicates with 15 ducks in each replicate. Diets for the two groups were basal diets supplemented with 0 or 300 mg/kg EGCG, respectively. All ducks were raised in the high temperature condition (35 ± 2 °C for 6 h from 10:00 to 16:00, and 28 ± 2 °C for the other 18 h from 16:00 to 10:00 the next day) for 21 days. Results showed that EGCG increased the egg production rate (p = 0.014) and enhanced the immunocompetence by improving serum levels of immunoglobulin A (p = 0.008) and immunoglobulin G (p = 0.006). EGCG also fortified the antioxidant capacity by activating superoxide dismutase (p = 0.012), catalase (p = 0.009), and glutathione peroxidase (p = 0.021), and increasing the level of heat-shock protein 70 (p = 0.003) in laying ducks’ liver. At the same time, hepatic metabolomics result suggested that EGCG increased the concentration of several key metabolites, such as spermidine (p = 0.031), tetramethylenediamine (p = 0.009), hyoscyamine (p = 0.026), β-nicotinamide adenine dinucleotide phosphate (p = 0.038), and pantothenic acid (p = 0.010), which were involved in the metabolic pathways of glutathione metabolism, arginine and proline metabolism, β-alanine metabolism, and tropane, piperidine, and pyridine alkaloid biosynthesis. In conclusion, 300 mg/kg dietary EGCG showed protection effects on the laying ducks reared in high temperature by improving the immune and antioxidant capacities, which contributed to the increase of laying performance of ducks. The potential mechanism could be that EGCG modulate the synthesis of key metabolites and associated metabolic pathways.

Highly responsive and sensitive non-enzymatic electrochemical sensor for the detection of β-NADH in food, environmental and biological samples using AuNP on polydopamine/titanium carbide composite.

In this study, a polydopamine/titanium carbide adorned with gold nanoparticles (Au@PDA/TiC) composite was prepared by a simple stirring technique and it was used for the dual-technique detection of β-Nicotinamide adenine dinucleotide (NADH). The Au@PDA/TiC-modified glassy carbon electrode (GCE) oxidized NADH at a very low oxidation potential of approximately 0.60V vs Ag/AgCl in pH=7.0 (0.1M PBS) via the transfer of two electrons and one proton (from NADH to NAD+). Based on the (i-t) amperometry mode, NADH can be quantified with a linear range of 0.018-674μM and LOD of 0.0062µM. In addition to the DPV mode, the electrochemical sensor had a linearity of 5-450µM with a LOD of 3.17µM. The developed sensor exhibited remarkable analytical performances concerning high sensitivity, electrocatalytic activity, low detection limit, wide linearity, appreciable specificity, repeatability, stability, reproducibility, and adequate recovery results in food, environmental and biological samples.

Fouling-resistant electrode for electrochemical sensing based on covalent-organic frameworks TpPA-1 dispersed cabon nanotubes

The key problem that limits the practical applications of nonenzymatic electrochemical sensors in biological media, is the biofouling and chemical fouling of electrodes due to the adsorption of biological molecules and oxidation (reduction) products. Electrode fouling will cause low accuracy, poor stability, and low sensitivity. Here, a simple and efficient antifouling electrode was demonstrated for electrochemical sensing based on covalent-organic framework (COF) TpPA-1 and carboxylic multi-walled carbon nanotubes (CNT) composites. COF TpPA-1 possesses abundant hydrophilic groups, which assisted the dispersion of CNT in water and formed uniform composites by π-π interaction. In addition, the introduction of CNT into the composites improved the electron transfer rate of COF TpPA-1. The antifouling interface was characterized by electrochemistry, contact angle measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The electrode showed good chemical and bio-fouling resistant performance for the electrochemical detection of β-nicotinamide adenine dinucleotide (NADH) and uric acid (UA) in real serum samples.

Investigation of flexible electrochemical sensor properties of graphite conductive ink modified textile products and their applications in electrical circuits

Smart textiles are of great interest due to their excellent applications in flexible and wearable devices. Therefore, in this study, conductive ink containing graphite was synthesized and conductive fabrics were obtained by coating the polyester/viscose blended fabric surface with the "dip and dry" method. Optimum conditions were determined by investigating the parameters that have an effect on the conductive fabric preparation such as dipping time, annealing temperature, time, and graphite amount. The resistivity value obtained from the optimum results is 0.075 Ω.cm. The characterization processes of the prepared conductive fabric were carried out by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction spectroscopy (XRD), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), and atomic force microscopy (AFM) methods. Then, the electrochemical sensor performance of the conductive fabric against dopamine, ascorbic acid, uric acid, and β-nicotinamide adenine dinucleotide reduced form (NADH), which are essential for human health, and its application in electrical circuits was investigated. The results show that the e-textile prepared with graphite conductive ink has the potential to be used in the production of flexible and wearable sensors, which will be developed especially in the healthcare field.

Effect of β-Nicotinamide Adenine Dinucleotide on Acute Allograft Rejection After Rat Lung Transplantation.

Rat single-lung transplantation was performed in 2 groups (n = 8 per group), using Brown-Norway donors and major histocompatibility complex-mismatched Lewis recipients. Recipients of the NAD+ group received 1000 mg/kg NAD+ intraperitoneally before transplantation and daily thereafter until euthanasia, whereas the control group received saline solution. At autopsy on day 5, blood samples were analyzed and the lung allograft was assessed by bronchioalveolar lavage, histology, and immunochemistry. The NAD+ group maintained an intact compliant lung tissue, a strong trend of lower acute cellular rejection (A3 versus A3-A4) and significantly less lymphocytic bronchiolitis (B0-B2R versus B1R-Bx). In addition, a trend of fewer alveolar CD68+ macrophages and significantly fewer interstitial CD163+ macrophages was observed. Bronchoalveolar lavage in the NAD+ group showed significantly fewer proinflammatory cytokines interleukin (IL)-6, IL-13, TNFα, and a protective IL-6/IL-10-ratio. In blood samples, we observed significantly fewer neutrophils, and proinflammatory GRO/KC in the NAD+ group. NAD+ might be a promising substance in prevention of acute allograft rejection in lung transplantation.

Monodisperse-porous silica microspheres with flexible phenylboronic acid functionalized-polycationic molecular brushes as a sorbent for teamed boronate affinity chromatography in batch and capillary column systems

Monodisperse-porous SiO2 microspheres carrying phenylboronic acid linked-flexible polycationic molecular brushes (SiO2@PEI-FPBA MS) was synthesized as a teamed boronate affinity (TBA) sorbent. The combination of enhanced porous properties of selected solid support with a multifunctional, macromolecular spacer arm allowed the synthesis of a superior boronate affinity sorbent (BAS) for batch and continous column chromatography. The sorbent was obtained by covalent binding of 4-formylphenylboronic acid (FPBA) to the polycationic macromolecular spacer-arm, polyethyleneimine (PEI) bound to SiO2 MS 6.3 µm in size. Molecular boronate affinity team on the sorbent was obtained for the first time, by the complex formation between phenylboronic acid (PBA) groups of bound FPBA and remaining primary amine groups of spacer-arm (i.e. branched PEI), by controlling the FPBA feed concentration. SiO2@PEI-FPBA MS obtained by lowering FPBA feed concentration exhibited high binding capacities for cis-diol functionalized biomolecules under neutral conditions as a typical behavior observed with previously produced TBA sorbents. FPBA content, pore volume and specific surface area of the sorbent were determined as 160.4 mg/g, 0.92 cc/g and 141.7 m2/g, respectively. The formation of a TBA complex by intermolecular B-N coordination on SiO2 MS was shown by X-ray photoelectron spectroscopy. The selection of PEI as a macromolecular, multifunctional spacer arm significantly enhanced either the cis-diol adsorption capacity by increasing FPBA content of the sorbent and also by forming a TBA complex with PBA groups. The selected cis-diol carrying agents and glycoproteins, β-nicotinamide adenine dinucleotide, ovalbumin (OVA) and transferrin (TRF) were isolated with the equilibrium adsorptions up to 149 mg/g sorbent and quantitative desorption yields. The comparison of cis-diol binding capacities of SiO2@PEI-FPBA MS obtained at neutral pH with the current TBA sorbents showed that the synthesis of a PEI-assisted TBA sorbent does not involve to include an external complexation agent in the synthesis. High glycoprotein binding capacities under neutral conditions can be obtained only by adjusting the FPBA content of a PEI assisted-TBA sorbent during the synthesis. A boronate affinity micro-chromatography system constructed by packing of SiO2@PEI-FPBA MS into a silica capillary (300 µm i.d.) was also successfully evaluated for the isolation of OVA with different flow rates.

Controlled Bipolar Doping of One-Dimensional van der Waals Nb2Pd3Se8.

Tailoring the electrical properties of one-dimensional (1D) van der Waals (vdW) materials is desirable for their applications toward electronic devices by exploiting their unique characteristics. However, 1D vdW materials have not been extensively investigated for modulation of their electrical properties. Here we control doping levels and types of 1D vdW Nb2Pd3Se8 over a wide energy range by immersion in AuCl3 or β-nicotinamide adenine dinucleotide (NADH) solutions, respectively. Through spectroscopic analyses and electrical characterizations, we confirm that the charges were effectively transferred to Nb2Pd3Se8, and the dopant concentration was adjusted to the immersion time. Furthermore, we make the axial p-n junction of 1D Nb2Pd3Se8 by a selective area p-doping using the AuCl3 solution, which exhibits rectifying behavior with an Iforward/Ireverse of 81 and an ideality factor of 1.2. Our findings could pave the way to more practical and functional electronic devices based on 1D vdW materials.

CycloZ Improves Hyperglycemia and Lipid Metabolism by Modulating Lysine Acetylation in KK-Ay Mice.

CycloZ, a combination of cyclo-His-Pro and zinc, has anti-diabetic activity. However, its exact mode of action remains to be elucidated. KK-Ay mice, a type 2 diabetes mellitus (T2DM) model, were administered CycloZ either as a preventive intervention, or as a therapy. Glycemic control was evaluated using the oral glucose tolerance test (OGTT), and glycosylated hemoglobin (HbA1c) levels. Liver and visceral adipose tissues (VATs) were used for histological evaluation, gene expression analysis, and protein expression analysis. CycloZ administration improved glycemic control in KK-Ay mice in both prophylactic and therapeutic studies. Lysine acetylation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha, liver kinase B1, and nuclear factor-κB p65 was decreased in the liver and VATs in CycloZ-treated mice. In addition, CycloZ treatment improved mitochondrial function, lipid oxidation, and inflammation in the liver and VATs of mice. CycloZ treatment also increased the level of β-nicotinamide adenine dinucleotide (NAD+), which affected the activity of deacetylases, such as sirtuin 1 (Sirt1). Our findings suggest that the beneficial effects of CycloZ on diabetes and obesity occur through increased NAD+ synthesis, which modulates Sirt1 deacetylase activity in the liver and VATs. Given that the mode of action of an NAD+ booster or Sirt1 deacetylase activator is different from that of traditional T2DM drugs, CycloZ would be considered a novel therapeutic option for the treatment of T2DM.

Flow injection assays for NADH and ethanol using photosensitized rose bengal and luminol-copper (II) chemiluminescence system.

The on-line photoreaction of rose bengal photosensitized luminol-copper (II) chemiluminescence (CL) system was used for the determination of β-nicotinamide adenine dinucleotide (NADH) and ethanol (EtOH) in pharmaceutical formulations combined with flow injection (FI) technique. NADH can significantly enhance the CL emission of the reaction. For EtOH, alcohol dehydrogenase (ADH) in soluble form was utilized in the presence of nicotinamide adenine dinucleotide (NAD+ ) resulting in NADH production. The limit of detection (3σ blank, 𝑛 = 3) of 4.0 × 10-8 and 2.17 × 10-5 M, and linear range of 1.3 × 10-7 -2.5 × 10-5 M (R2 = 0.9998, n = 6) and 0.11-2.17 × 10-3 M (R2 = 0.9996, n = 6) were obtained for NADH and EtOH respectively. The injection rate was 100 h-1 with relative standard deviation (RSD; n = 3) of 1.5%-4.8% in the range studied for both analytes. The procedure was satisfactorily applied to pharmaceutical formulations with recoveries in the range of 91.6 ± 3.0%-110 ± 2.0% for NADH and 88 ± 3.0%-95.4 ± 4.0% for EtOH. The results obtained were very consistent and did not differ considerably from the reported approaches at 95% confidence limit. The possible mechanism of CL reaction is also explained briefly.

Erchen decoction to reduce oxidative stress in dyslipidemia phlegm-dampness retention syndrome mice: In vivo mechanism revealed by metabolomics (liquid chromatography–mass spectrometry)

ObjectiveErchen decoction, a traditional Chinese medicine formula, can reduce the level of oxidative stress for the treatment of dyslipidemia phlegm-dampness retention syndrome (DPDRS); however, studies have not elucidated the mechanism underlying its metabolic action. Here, liquid chromatography–mass spectrometry (LC–MS)-based metabolomic techniques were utilized to characterize the in vivo effects of Erchen decoction in achieving reduction of oxidative stress levels and understand the potential metabolic mechanisms of action. MethodsWe constructed a DPDRS animal model using a multifactorial composite modeling approach, and Erchen decoction was administered by gavage. We employed LC–MS-based metabolomic techniques in combination with serum-associated factors, gene transcription, methylation detection, and hematoxylin and eosin staining. ResultsIn this study, the constructed animal model of DPDRS had satisfactory quality. Erchen decoction treatment reduced the levels of low-density lipoprotein cholesterol, t total cholesterol and riglyceride; it improved the endothelial structure, increased levels of serum β-nicotinamide adenine dinucleotide phosphate and glutathione concentrations, increased aortic phosphoserine aminotransferase and phosphoserine phosphatase gene expression levels, and decreased aortic phosphoglycerate dehydrogenase methylation level. A total of 64 differential metabolites were obtained using LC–MS assay, and 34 differential metabolic pathways were obtained after enrichment. ConclusionsErchen decoction treatment of DPDRS mice reversed lipid indexes, improved vascular endothelial structure, increased serum and aortic anti-oxidative stress factor concentration and expression levels, and decreased methylation levels, thereby reducing oxidative stress and protecting vascular endothelium. Tricarboxylic acid cycle and metabolic pathways of serum glutamine, serine, tryptophan, pyrimidine, and pyruvate were the most relevant metabolic pathways involved in reducing oxidative stress levels by Erchen decoction during DPDRS treatment; especially, mitochondrial redox homeostasis maintenance in endothelial cells may be crucial. In this work, the therapeutic potential of Erchen decoction for reducing the oxidative stress level in DPDRS was demonstrated; however, its in-depth mechanism is worth further exploration.

Application of NAD+-Dependent Electrochemical Dehydrogenase Biosensors in Human Physiological Fluids: Opportunities and Challenges

Electrochemical enzymatic biosensors represent a promising, low-cost technology for point-of-care (POC) diagnostics that allows fast response and simple sample processing procedures. In this review, we summarize up-to-date literature on NAD+/NADH (β-nicotinamide adenine dinucleotide)-dependent electrochemical dehydrogenase biosensors and highlight their applications in human physiological fluids. A brief comparison of various enzyme immobilization procedures is first presented, discussing preparation processes and principal analytical performance characteristics. In the following section, we briefly discuss classes of biosensors based on redox mediators-mediated electron transfer systems (METs). Finally, the conclusion section summarizes the ongoing challenges in the fabrication of NAD+-dependent electrochemical dehydrogenase biosensors and gives an outlook on future research studies.

Improved Yield for the Enzymatic Synthesis of Radiolabeled Nicotinamide Adenine Dinucleotide.

Labeled β-nicotinamide adenine dinucleotide (NAD) analogues have been critical for uncovering new biochemical connections and quantitating enzymatic activity. They function as tracers for enzymology, flux analyses, and in situ measurements. Nevertheless, there is limited availability of specific types of analogues, especially radiolabeled NAD isotopologues. Here, we describe an improved enzymatic synthesis reaction for 32P- NAD+ with a yield of 98% ± 1%, using lowered concentrations of reactants and standard equipment. This represents the highest reported yield for the enzymatic synthesis of NAD+ to date. With the high yield we were able to directly use the reaction product to generate derivatives, such as 32P-NADP. The high-yield enzymatic synthesis is versatile for a broad variety of labels and NAD derivatives. Its advantages include lowered concentrations of reactants, providing sufficient amounts of product for downstream applications, and minimizing intermediate purification steps.

Electrochemical sensing of NADH using 4-nitrobenzenediazonium tetrafluoroborate salt functionalized multiwalled carbon nanotubes.

In this work, multiwalled carbon nanotubes (MWCNTs) are functionalized using 4-nitrobenzenediazonium (NBD) salt, which is identified as an effective electrocatalyst for the detection of β-nicotinamide adenine dinucleotide (NADH). The NBD functionalized MWCNT (NBD-MWCNT(w) (w-washed)) was characterized using various physicochemical characterization methods. Cyclic voltammetric measurements showed that NBD-MWCNT(w) modified glassy carbon electrode (NBD-MWCNT(w)/GCE) was able to produce the anodic wave for oxidizing NADH at the applied overpotential of 0.12 V, which is 0.67 V cathodic when compared to that of bare GCE. Besides, the sensitivity of the electrode also doubled. The sensitivity and limit of detection (LoD) were 8.5 × 10-4 A M-1 and 3.75 μM, respectively. The linear range of the sensor was 5 to 60 μM. The selectivity studies further proved that the matrix is specific towards detecting NADH in the presence of other possible interfering molecules. The diffusion co-efficient and apparent rate constant of NADH obtained were 3.8 × 10-6 cm2 s-1 and 1.12 × 107 mol-1 cm3 s-1 respectively. Additionally, the electrode is employed to detect the analyte in real samples.

Corrigendum to “A β-nicotinamide adenine dinucleotide electrochemical sensor based on polyoxometalate built by the combination of electrodeposition and self-assembly” [J. Electroanal. Chem. 907 (2022) 116083

Corrigendum to “A β-nicotinamide adenine dinucleotide electrochemical sensor based on polyoxometalate built by the combination of electrodeposition and self-assembly” [J. Electroanal. Chem. 907 (2022) 116083

Adsorption Behavior of the Coenzyme NADH at the Carbon/Electrolyte Interface Determined by Neutron Reflectometry.

The adsorption behavior of β-nicotinamide adenine dinucleotide (NADH) at the carbon/electrolyte interface has been studied using a combination of neutron reflectometry (NR) and solution depletion isotherms. Coupling the NR technique with an electrochemical cell allowed in situ observation of the reversible adsorption and desorption of the molecule at the electrode surface over a range of applied potentials. The overall surface coverage was low (30-50%), suggesting adsorption only at specific defect sites on the surface. Isotherms conducted over a range of temperatures were used to extract thermodynamic parameters, which implied strong physisorption via electrostatic interactions. In addition, changes in the outermost layer of the carbon electrode were observed as the applied potential was varied, which were confirmed with ex situ X-ray reflectivity measurements (XRR). X-ray photoelectron spectroscopy (XPS) measurements of the carbon surface demonstrated the majority of carbon atoms were in an sp2 state.

AIE Polymer Micelle/Vesicle Photocatalysts Combined with Native Enzymes for Aerobic Photobiocatalysis

Biocatalytic transformation has attracted increasing attention in the green synthesis of chemicals due to the diversity of enzymes, their high catalytic activities and specificities, and environmentally benign conditions. Most redox enzymes in nature are dependent on nicotinamide cofactors like β-nicotinamide adenine dinucleotide (NAD+)/reduced nicotinamide adenine dinucleotide (NADH). The use of solar energy, especially visible light, in the regeneration of cofactors through the combination of photocatalysis and biocatalysis provides an extraordinary opportunity to make complete green processes. However, the combination of photocatalysts and enzymes has been challenged by the rapid degradation and deactivation of the enzymatic material by photogenerated reactive oxygen species (ROS). Here, we design core-shell structured polymer micelles and vesicles with aggregation-induced emission (AIE) as visible-light-mediated photocatalysts for highly stable and recyclable photobiocatalysis under aerobic conditions. NAD+ from NADH can be efficiently regenerated by the photoactive hydrophobic core of polymer micelles and the hydrophobic membrane of polymer vesicles, while the enzymatic material (glucose 1-dehydrogenase) is screened from the attack of photogenerated ROS by the hydrophilic surface layer of polymer colloids. After at least 10 regeneration cycles, the enzyme keeps its active state; meanwhile, polymer micelles and vesicles maintain their photocatalytic activity. These polymer colloids show the potential to be developed for the implementation of industrially relevant photobiocatalytic systems.