Determination Of NADH Research Articles

Electrochemical determination of nicotinamide adenine dinucleotide and hydrogen peroxide based on poly(xanthurenic acid), flavin adenine dinucleotide and functionalized multi-walled carbon nanotubes

A bifunctional sensor for determination of reduced β-nicotinamide adenine dinucleotide (NADH) and hydrogen peroxide (H2O2) has been successfully fabricated by xanthurenic acid (Xa), flavin adenine dinucleotide (FAD), and functionalized carbon nanotubes (CNTs). The hybrid composites can be easily prepared by the electrocodeposition of polyXa/FAD and the adsorption of functionalized CNTs. These composites can be constructed of “polyXa/FAD/CNTs” and “CNTs/polyXa/FAD” according to the immobilization order of polyXa/FAD “before” and “after” the adsorption of CNTs. They are surface-confined and stable in various scan rates and different pH conditions. Particularly, the polyXa/FAD/MWCNTs show more efficient activity to target species due to the compact structure and more active surface area. It provides linear concentration range of 5×10−6–1.7×10−4M and 1×10−4–2.9×10−3M, with sensitivity of 155μAmM−1cm−2 and 60μAmM−1cm−2, and detection limit of 10−6M and 10−4M (S/N=3) for NADH and H2O2, respectively. No interference except of the case for NADH determination in the presence of AA. It can be a good electrocatalyst to determine NADH and H2O2 and the linear sweep voltammetry (LSV) technique can help to analyze NADH from the AA interference.

Amperometric determination of NADH with Co3O4 nanosheet modifiedelectrode

In this work, we have developed a simple and reliable cobalt oxide (Co3O4) based amperometric sensor for the determination of NADH. A sheet shape Co3O4 nanooxide was synthesized by the CTAB assisted hydrothermal technique and was characterized by SEM and XPS. Owing to the redox property of Co3O4, the operating potential of NADH can be significantly reduced from 0.7down to 0.1V. Compared to a commercial Co3O4 nanoparticle modified electrode, this nanosheet form cobalt oxide possesses a rapid background subsiding characteristic and a low residual current. This scheme was conducted on a flow injection system with a constant operating potential of 0.1V (vs. Ag/AgCl, 3M) in a 0.2M phosphate buffer at pH 6.0. A suitable linear range from 10 to 100μM (R=0.999) with a detection limit of 4.25μM (S/N=3) was obtained. The RSD for 20 successive measurements of 75μM NADH is only 1.4%, which indicates a high stability and no contamination during NADH oxidation. This scheme did not suffer from conventional antioxidants, including dopamine, uric acid, epinephrine, serotonin, histamine, and 4-acetaminophen, except ascorbic acid. Thus, an ascorbate oxidase was introduced to remove the ascorbic acid before the sample was injected into the flow injection analysis system. After this simple pretreatment, the influence of ascorbic acid was eliminated, successfully.

A Hydrazine Coupled Cycling Assay Validates the Decrease in Redox Ratio under Starvation in Drosophila

A commonly used enzymatic recycling assay for pyridine nucleotides has been adapted to directly measure the NAD+/NADH redox ratio in Drosophila melanogaster. This method is also suitable for quantification of NADP+ and NADPH. The addition of a coupling reaction removing acetaldehyde produced from the alcohol dehydrogenase (ADH) reaction was shown to improve the linearity of NAD(H) assay. The advantages of this assay method are that it allows the determination of both NAD+ and NADH simultaneously while keeping enzymatic degradation of pyridine nucleotides minimal and also achieving better sensitivity. This method was used to determine the redox ratio of D. melanogaster and validated substantial decrease of redox ratio during starvation.

Optical detection of NADH based on biocatalytic growth of Au–Ag core–shell nanoparticles

We have developed an optical assay for NADH (Dihydronicotinamide adenine dinucleotide) based on the catalytic growth of gold–silver core–shell nanoparticles (Au–Ag–CSNPs). The nanoparticles were immobilized on pretreated glass slide and are shown to catalyze the NADH-mediated reduction of Ag(I) ions in the presence of 1,4-benzoquinone and cetyltrimethyl ammonium ion. This leads to the formation of Au–Ag–CSNPs on the glass. The absorption peak of the Au–Ag–CSNPs at 415nm increases with the concentration of NADH in the solution used, and this can be measured by UV–vis photometry. High-resolution scanning electron microscopy analysis of the morphology of the surface of the Au–Ag–CSNPs before and after the catalytic reaction revealed a growth of their diameter. Under optimal conditions, NADH can be determined in the concentration range from 0.2 to 3.2mM, and the detection limit is 15.6μM. The sensor has good precision and good storage stability, simple in operation, and can be fabricated at low costs, which made it suitable for the determination of NADH in complex biological systems and in related degradation processes of contaminants.

A simple route to fabricate controllable and stable multilayered all-MWNTs films and their applications for the detection of NADH at low potentials

This study demonstrates a polyelectrolyte-free method to fabricate controllable and stable all-MWNTs films via a covalent layer-by-layer (LBL) deposition. Aminated MWNTs and carboxylated MWNTs were prepared by surface functionalization, allowing the incorporation of MWNTs into highly tunable thin films through the formation of covalent amide bonds. Fourier transform infrared spectroscopy (FTIR) analysis demonstrated the formation of covalent linkages between MWNTs layers. Scanning electron microscopy (SEM) and ultraviolet–visible spectroscopy (UV–vis) were used to characterize the assembly process. Electrochemical studies indicated that the all-MWNTs film possessed a remarkable electrocatalytic activity toward dihydronicotinamide adenine dinucleotide (NADH) at relatively low potentials, without the need for redox mediators. The film thickness and the amount of assembled MWNTs were readily adjusted by simply changing the number of cycles in the LBL assembly process, which also effectively tuned the electrocatalytic activity of the film toward NADH. The film constructed with four bilayers showed a high sensitivity of 223.8μAmM−1cm−2 and a detection limit of 1.5μM, with a fast response of less than 3s. Furthermore, the all-MWNTs film also showed good selectivity and excellent stability for the determination of NADH.

Ultrasensitive photoelectrochemical sensing of nicotinamide adenine dinucleotide based on graphene-TiO2 nanohybrids under visible irradiation

In this paper, the photoelectrochemical behavior of graphene-TiO2 (G-TiO2) nanohybrids was investigated in the visible region and a new photoelectrochemical sensor for sensitive determination of nicotinamide adenine dinucleotide (NADH) was proposed. Under visible light, the G-TiO2 nanohybrids possessed enhanced photocurrent, which was nearly 5 times than that of pure TiO2 nanocrystals (NCs). Based on the enhanced photocurrent of G-TiO2 nanohybrids toward NADH, a new photoelectrochemical methodology for ultrasensitive determination of NADH was developed. The proposed sensor showed linearly enhanced photocurrent by increasing the NADH concentration from 1.0×10−8 to 2.0×10−3M with a low detection limit of 3.0×10−9M. Furthermore, this sensor exhibited good selectivity and stability towards NADH determination. This strategy opens up a new avenue for the application of graphene-based hybrids in the field of photoelectrochemical sensing and monitoring.

Electrochemical determination of NADH based on MPECVD carbon nanosheets

Characterization and application of carbon nanosheets (CNSs) grown by microwave plasma enhanced chemical vapor deposition (MPECVD) have been investigated for the electrochemical biosensor. The as-grown CNS films possess a porous structure with a large amount of graphene edges which most of them are less than 2nm in thickness, as confirmed by scanning and transmission electron microscopes. “Surface-sensitive” probe, Fe(CN)63−/4−, exhibits that the original CNSs have faster electron transfer than glassy carbon electrode, owing to much more edge plane sites on the original CNS surface. “Oxygen-sensitive” probe, Fe3+/2+ also confirmed that the oxygen species in the CNS film can improve its electrochemical activity. The modified electrode by MPECVD CNS films has been used to detect NADH for the first time. The CNSs with many graphene edges efficiently catalyse the oxidation of NADH at 0.336V. The biosensor linearly responds to NADH in the range of 0–500μM (R=0.99665), the sensitivity of the electrode is 85.8mA M−1 or 715mAM−1cm−2, and the detection limit of NADH is about 0.44μM (S/N=3). The biosensor also displays excellent stability for NADH detection and good selectivity in the interference from ascorbic acid.

Sensitive colorimetric visualization of dihydronicotinamide adenine dinucleotide based on anti-aggregation of gold nanoparticles via boronic acid–diol binding

A facile, highly sensitive colorimetric strategy for dihydronicotinamide adenine dinucleotide (NADH) detection is proposed based on anti-aggregation of gold nanoparticles (AuNPs) via boronic acid–diol binding chemistry. The aggregation agent, 4-mercaptophenylboronic acid (MPBA), has specific affinity for AuNPs through Au–S interaction, leading to the aggregation of AuNPs by self-dehydration condensation at a certain concentration, which is responsible for a visible color change of AuNPs from wine red to blue. With the addition of NADH, MPBA would prefer reacting with NADH to form stable borate ester via boronic acid–diol binding dependent on the pH and solvent, revealing an obvious color change from blue to red with increasing the concentration of NADH. The anti-aggregation effect of NADH on AuNPs was seen by the naked eye and monitored by UV–vis extinction spectra. The linear range of the colorimetric sensor for NADH is from 8.0×10−9M to 8.0×10−6M, with a low detection limit of 2.0nM. The as-established colorimetric strategy opened a new avenue for NADH determination.

Effective immobilization of Ru(bpy)32+ by functional composite phosphomolybdic acid anion on an electrode surface for solid-state electrochemiluminescene to sensitive determination of NADH

Phosphomolybdic acid anion ([PMo12O40]3−) was used for the immobilization of ruthenium(II) tris(bipyridine) (Ru(bpy)32+) on an electrode surface to yield a sensitive solid-state electrogenerated chemiluminescence (ECL) sensor. [PMo12O40]3− anion in the prepared sensor had catalytic ability to the NADH oxidation. The ECL signal of the Ru(bpy)32+/[PMo12O40]3− film was about 3-fold enhancement than that for the Ru(bpy)32+/Nafion film to NADH determination. The resulting ECL sensor exhibited a wide linear range from 2.5×10−7 to 5.0×10−3M (R=0.99) with the detection limit of 1.67×10−8M (S/N=3). In addition, it had good reproducibility and excellent long-term stability, and the relative average deviation was 0.77% of ECL intensity–time curve under continuous potential scanning for 21 cycles; after being used in two weeks, the sensor was able to keep over 90% activity toward 25μM NADH. Fabrication of the ECL sensor by this method is simple and easy. Such superior properties will promote the application of polyoxometalates in fabricating sensors for using in electroanalytical and biochemical analysis.

Detection of NADH and ethanol at a graphite electrode modified with titania sol-gel/Meldola’s Blue/MWCNT/Nafion nanocomposite film

Abstract For electrocatalytic determination of NADH, a graphite electrode modified with titania sol-gel/Meldola’s Blue/MWCNT/Nafion nanocomposite was proposed. The composition of the matrix film was optimised in terms of the content of carbon nanotubes and Nafion. Incorporation of a redox mediator, Meldola’s Blue, into the nanocomposite film enabled electrocatalytic determination of NADH at a low potential, −50 mV. For determination of ethanol, alcohol dehydrogenase (ADH) was immobilized into the matrix layer. Experimental conditions affecting the biosensor response were examined, including enzyme loading, temperature of measurement and pH of background electrolyte. Assessments of the analytical characteristics of the biosensor were performed with respect to sensitivity, limit of detection, operational stability, repeatability and reproducibility. The proposed biosensor showed electrocatalytic activity toward oxidation of ethanol with sensitivity of 2.24 µA L mmol−1, linear range from 0.05 to 1.1 mmol L−1, and limit of detection of 25 µmol L−1. The apparent Michaelis-Menten constant was 1.24 mmol L−1, indicating a high biological affinity of ADH/titania sol-gel/Meldola’s Blue/MWCNT/Nafion electrode for ethanol. The developed biosensor was tested in determinations of ethanol content in alcoholic beverages.

Electrooxidative Polymerization of Methylene Blue on Screen Printed Carbon Paste Electrode and Its Application in NADH Determination

The electropolymerization of methylene blue (MB) from the phenothiazine group on screen printed carbon paste electrode (SPCE) has been successfully studied using repeated potential cycling. The characteristics of the modified electrodes were influenced by several experimental conditions such as MB concentration, scan rate, scanning range and number of cyclic scans. The catalytic properties of the modified electrodes allowed NADH oxidation at a lower potential of +0 08 V versus Ag/AgCl. The resulting modified electrodes also exhibited a linear response towards NADH in the concentration range of 10 to 100 M with the detection limit of 10 M.

Electrocatalytic oxidation of NADH on a glassy carbon electrode modified with MWCNT-Pd nanoparticles and poly 3,4-ethylenedioxypyrrole

An NADH biosensor based on MWCNTs-Pd nanoparticles and polymerized 3,4-ethylenedioxypyrrole (PEDOP) was developed and characterized. PEDOP/MWCNTs-Pd/GCE was prepared quickly and simply and showed improved sensitivity to NADH. Comparable results were obtained by cyclic voltammetric (CV) and amperometric methods for NADH determination. The amperometric method gave short response times, and linear regression was observed at concentrations below 1.0mM. The proposed NADH biosensor exhibited a wide linear response range of 1μM–13mM during amperometric testing using an applied potential of 0.42V, with a low detection limit of 0.18μM (S/N=3). The sensor demonstrated fast responses and good stability.

A Bifunctional Biosensor for Determination of H2O2 and NADH Using Polyaniline, Silicomolybdate, and MWCNT Hybrid Composites

A Bifunctional Biosensor for Determination of H2O2 and NADH Using Polyaniline, Silicomolybdate, and MWCNT Hybrid Composites

Electropolymerized poly(Toluidine Blue)-modified carbon felt for highly sensitive amperometric determination of NADH in flow injection analysis

Poly(pheniothiazine) films were prepared on a porous carbon felt (CF) electrode surface by an electrooxidative polymerization of three phenothiazine derivatives (i.e.,Tthionine (TN), Toluidine Blue (TB) and Methylene Blue (MB)) from 0.1 mol/L phosphate buffer solution (pH 7.0). Among the three phenothiazies, the poly(TB) film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form (NADH) at +0.2 V vs. Ag/AgCl. The poly(TB) film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH. The peak currents (peak heights) were almost unchanged, irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min, resulting in the measurement of NADH (ca. 30 samples/hr) at 4.1 mL/min. The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 μmol/L (sensitivity: 0.318 μA/(μmol/L); correlation coefficient: 0.997). The lower detection limit was found to be 0.3 μmol/L ( S/N = 3).

Electrochemical determination of NADH using a glassy carbon electrode modified with Fe3O4 nanoparticles and poly-2,6-pyridinedicarboxylic acid, and its application to the determination of antioxidant capacity

We have prepared a glassy carbon electrode modified with poly-2,6-pyridinedicarboxylic acid and with magnetic Fe3O4 nanoparticles. This modification enhances the effective surface area and the electrocatalytic oxidation of nicotinamide adenine dinucleotide (NADH) in addition to providing positively charged groups for electrostatic assembly of the phosphate group of NADH. The modified electrode responds linearly to NADH in the range from 5 × 10−8 to 2.5 × 10−5 M and gives a lower detection limit of 1 × 10−8 M. It displays satisfactory selectivity and reproducibility. The sensor was applied to rapid screening of plant extracts for their antioxidant properties.

Electrochemical biosensors based on redox carbon nanotubes prepared by noncovalent functionalization with 1,10-phenanthroline-5,6-dione

To improve the electrocatalytic activities of carbon nanotubes (CNT) towards the oxidation of nicotinamide adenine dinucleotide (NADH), we derive them with a redox mediator, 1,10-phenanthroline-5,6-dione (PD), by the noncovalent functionalization method. The redox carbon nanotubes (PD/CNT/GC) show excellent electrocatalytic activities towards the oxidation of NADH (catalytic reaction rate constant, k(h) = 7.26 × 10(3) M(-1) s(-1)), so the determination of NADH can be achieved with a high sensitivity of 8.77 μA mM(-1) under the potential of 0.0 V with minimal interference. We also develop an amperometric ethanol biosensor by integration of alcohol dehydrogenase (ADH) within the redox carbon nanotubes (PD/CNT/GC). The ethanol biosensor exhibits a wide linear range up to 7 mM with a lower detection limit of 0.30 mM as well as a high sensitivity of 10.85 nA mM(-1).

Meldola’s Blue — doped titania sol-gel sensor for NADH determination

Abstract Titania layers obtained by a sol-gel technique doped with redox mediator, Meldola’s Blue, were employed for construction of a new NADH senor. Optimization of preparation process as well as experimental conditions affecting the response of the sensor were examined. Under optimal conditions NADH could be determined in the wide linear range from 90 to 2300 µM with detection limit 12 µM and a high sensitivity 12.5 nA µM−1. The usefulness of developed sensor was preliminarily checked in determination of NADH forming during enzymatic oxidation of ethanol catalyzed by alcohol dehydrogenase (ADH).

Photoelectrocatalytic determination of NADH in a flow injection system with electropolymerized methylene blue

It was firstly described that a glassy carbon electrode electropolymerized with methylene blue shows an efficient photoelectrocatalytic activity towards NADH oxidation in a phosphate buffer solution (pH 7.0). In order to perform the photoelectrocatalytic determination of NADH in a flow injection analysis (FIA) system, a home-made flow electrochemical cell with a suitable transparent window for the irradiation of the electrode surface was constructed. The currents obtained from the photoamperometric measurements in the FIA system at optimum conditions (flow rate of carrier solution, 1.3 mL min −1; transmission tubing length, 10 cm; injection volume, 100 μL; and constant applied potential, +150 mV vs. Ag/AgCl) were linearly dependent on the NADH concentration and linear calibration curves were obtained in the range of 1.0 × 10 −7–2.0 × 10 −4 M. The detection limit was found to be 4.0 × 10 −8 M for photoamperometric determination of NADH.

One-step construction of an electrode modified with electrodeposited Au/SiO2 nanoparticles, and its application to the determination of NADH and ethanol

A new electrode was developed by one-step potentiostatic electrodeposition (at −2.0 V for 20 s) of Au/SiO2 nanoparticles on a glassy carbon electrode. The resulting electrode (nano-Au/SiO2/GCE) was characterized by scanning electronic microscopy, X-ray photoelectron spectroscopy and electrochemical techniques. The electrochemical behavior of dihydronicotinamide adenine dinucleotide (NADH) at the nano-Au/SiO2/GCE were thoroughly investigated. Compared to the unmodified electrode, the overpotential decreased by about 300 mV, and the current response significantly increased. These changes indicated that the modified electrode showed excellent catalytic activity in the oxidation of NADH. A linear relationship was obtained in the NADH concentration range from 1.0 × 10−6 to 1.0 × 10−4 mol L−1. In addition, amperometric sensing of ethanol at the nano-Au/SiO2/GCE in combination with alcohol dehydrogenase and nicotinamide adenine dinucleotide was successfully demonstrated. A wide linear response was also found for ethanol in the range from 5.0 × 10−5 to 1.0 × 10−3 mol L−1 and 1.0 × 10−3 to 1.0 × 10−2 mol L−1, respectively. The method was successfully applied to determine ethanol in beer and biological samples.

Simultaneous determination of levodopa, NADH, and tryptophan using carbon paste electrode modified with carbon nanotubes and ferrocenedicarboxylic acid

The redox response of a modified carbon nanotube paste electrode of ferrocenedicarboxylic acid was investigated. Cyclic voltammetry, differential pulse voltammetry, and chronoamperometry were used to investigate the electrochemical behavior of levodopa (LD) at modified electrode. Under the optimized conditions (pH 5.0), the modified electrode showed high electrocatalytic activity toward LD oxidation; the overpotential for the oxidation of LD was decreased by more than 190 mV, and the corresponding peak current increased significantly. Differential pulse voltammetric peak currents of LD increased linearly with its concentrations at the range of 0.04 to 1,100 μM, and the detection limit (3σ) was determined to be 12 nM. The diffusion coefficient \( \left( {D = {9}.{2} \times {1}{0^{ - {6}}}{\hbox{c}}{{\hbox{m}}^2}/{\hbox{s}}} \right) \) and transfer coefficient (α = 0.49) of LD were also determined. Mixture of LD, NADH, and tryptophan (TRP) can be separated from one another by differential pulse voltammetry. These conditions are sufficient to allow determination of LD, NADH, and TRP both individually and simultaneously. The modified electrode showed good reproducibility, remarkable long-term stability, and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for determination of LD, NADH, and TRP in real samples such as urine and water samples.