Search results for: Potassium Ferrocyanide Solution (3%)
#32946485 2020/09/18 To Up
Transformation of low molecular compounds and soil humic acid by two domain laccase of Streptomyces puniceus in the presence of ferulic and caffeic acids.The two-domain bacterial laccases oxidize substrates at alkaline pH. The role of natural phenolic compounds in the oxidation of substrates by the enzyme is poorly understood. We have studied the role of ferulic and caffeic acids in the transformation of low molecular weight substrates and of soil humic acid (HA) by two-domain laccase of Streptomyces puniceus (SpSL, previously undescribed). A gene encoding a two-domain laccase was cloned from S. puniceus and over-expressed in Escherichia coli. The recombinant protein was purified by affinity chromatography to an electrophoretically homogeneous state. The enzyme showed high thermal stability, alkaline pH optimum for the oxidation of phenolic substrates and an acidic pH optimum for the oxidation of K4[Fe(CN)6] (potassium ferrocyanide) and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt). Phenolic compounds were oxidized with lower efficiency than K4[Fe(CN)6] and ABTS. The SpSL did not oxidize 3.4-dimethoxybenzoic alcohol and p-hydroxybenzoic acid neither in the absence of phenolic acids nor in their presence. The enzyme polymerized HA-the amount of its high molecular weight fraction (>80 kDa) increased at the expense of low MW fraction (10 kDa). The addition of phenolic acids as potential mediators did not cause the destruction of HA by SpSL. In the absence of the HA, the enzyme polymerized caffeic and ferulic acids to macromolecular fractions (>80 kDa and 10-12 kDa). The interaction of SpSL with HA in the presence of phenolic acids caused an increase in the amount of HA high MW fraction and a two-fold increase in the molecular weight of its low MW fraction (from 10 to 20 kDa), suggesting a cross-coupling reaction. Infrared and solution-state 1H-NMR spectroscopy revealed an increase in the aromaticity of HA after its interaction with phenolic acids. The results of the study expand our knowledge on the transformation of natural substrates by two-domain bacterial laccases and indicate a potentially important role of the enzyme in the formation of soil organic matter (SOM) at alkaline pH values.
Liubov I Trubitsina, Alexander V Lisov, Oxana V Belova, Ivan V Trubitsin, Vladimir V Demin, Andrey I Konstantinov, Anna G Zavarzina, Alexey A Leontievsky
1452 related Products with: Transformation of low molecular compounds and soil humic acid by two domain laccase of Streptomyces puniceus in the presence of ferulic and caffeic acids.10 mg 5 G100 mg100ug200 1000 tests100 ug600 Tests / Kit500 MG 1 G500 mg
#32033445 2020/02/05 To Up
Determination of Iron Valence States Around Pits and the Influence of Fe on the Pitting Corrosion of 304 Stainless Steel.Potassium ferricyanide and potassium ferrocyanide were used to observe and monitor the pitting corrosion of 304 stainless steel (SS) at anodic polarization in situ. The results show that there are Fe ions around the corrosion pit when pitting occurs on 304 SS in NaCl aqueous solution. The effect of Fe surrounded pits on the pitting corrosion was also studied by testing the electrochemical behavior of 304 SS in different Fe/Fe solutions. The presence of Fe leads to the positive shift of corrosion potential and the increase of corrosion rate of 304 SS. There are two possible reasons for this phenomenon. On the one hand, Fe hydrolysis results in the decrease of pH value of solution. At the same iron ion concentration, the higher the Fe ion concentration, the lower the solution pH value. On the other hand, Fe may reduce on the electrode surface. The decrease of solution pH and the reduction of Fe resulted in the acceleration of the corrosion rate.
Hao Zhang, Nan Du, Shuaixing Wang, Qing Zhao, Wenjie Zhou
2121 related Products with: Determination of Iron Valence States Around Pits and the Influence of Fe on the Pitting Corrosion of 304 Stainless Steel.5 G50 IU100.00 ul1500 Units 100ul
#31341328 // To Up
Design and Finite Element Model of a Microfluidic Platform with Removable Electrodes for Electrochemical Analysis.A microfluidic platform for hydrodynamic electrochemical analysis was developed, consisting of a poly(methyl methacrylate) chip and three removable electrodes, each housed in 1/16" OD polyether ether ketone tube which can be removed independently for polishing or replacement. The working electrode was a 100-μm diameter Pt microdisk, located flush with the upper face of a 150 μm × 20 μm × 3 cm microchannel, smaller than previously reported for these types of removable electrodes. A commercial leak-less reference electrode was utilized, and a coiled platinum wire was the counter electrode. The platform was evaluated electrochemically by oxidizing a potassium ferrocyanide solution at the working electrode, and a typical limiting current behavior was observed after running linear sweep voltammetry and chronoamperometry, with flow rates 1-6 μL/min. While microdisk channel electrodes have been simulated before using a finite difference method in an ideal 3D geometry, here we predict the limiting current using finite elements in COMSOL Multiphysics 5.3a, which allowed us to easily explore variations in the microchannel geometry that have not previously been considered in the literature. Experimental and simulated currents showed the same trend but differed by 41% in simulations of the ideal geometry, which improved when channel and electrode imperfections were included.
Daniel E Molina, Adan Schafer Medina, Haluk Beyenal, Cornelius F Ivory
1076 related Products with: Design and Finite Element Model of a Microfluidic Platform with Removable Electrodes for Electrochemical Analysis.1 module100 mg 100 G5mg1 module 25 MG200ug 15 ml 1 module25 mg 1 G
#30227811 // To Up
Serological Electrodetection of Rheumatoid Arthritis Using Mimetic Peptide.Rheumatoid arthritis is the most common inflammatory autoimmune disease in the world. Recently new targets for its detection were developed as alternatives to classic biomarkers, including the M-12 peptide, that mimics carbonic anhydrase III. Thus, the application of this peptide for the development of new detection devices is attractive.
Danielle Alves de Oliveira, Vinicíus de Rezende Rodovalho, José Manuel Rodrigueiro Flauzino, Heliane Souza da Silva, Galber Rodrigues Araujo, Emília Rezende Vaz, Carlos Ueira Vieira, João Marcos Madurro, Ana Graci Brito Madurro
1275 related Products with: Serological Electrodetection of Rheumatoid Arthritis Using Mimetic Peptide.50 ug50 ug50 ug50 ug50 ug100ug50 ug50 ug50 ug50 ug50 ug20
#29713161 2018/04/17 To Up
Role of Au(NPs) in the enhanced response of Au(NPs)-decorated MWCNT electrochemical biosensor.The combination of Au-metallic-NPs and CNTs are a new class of hybrid nanomaterials for the development of electrochemical biosensor. Concentration of Au(nanoparticles [NPs]) in the electrochemical biosensor is crucial for the efficient charge transfer between the Au-NPs-MWCNTs modified electrode and electrolytic solution.
Shahid Mehmood, Regina Ciancio, Elvio Carlino, Arshad S Bhatti
2942 related Products with: Role of Au(NPs) in the enhanced response of Au(NPs)-decorated MWCNT electrochemical biosensor.100 UG 5 G96T96T1
#29513951 // To Up
XYLITOL IMPROVES ANTI-OXIDATIVE DEFENSE SYSTEM IN SERUM, LIVER, HEART, KIDNEY AND PANCREAS OF NORMAL AND TYPE 2 DIABETES MODEL OF RATS.The present study investigated the anti-oxidative effects of xylitol both in vitro and in vivo in normal and type 2 diabetes (T2D) rat model. Free radical scavenging and ferric reducing potentials of different concentrations of xylitol were investigated in vitro. For in vivo study, six weeks old male Sprague-Dawley rats were divided into four groups, namely: Normal Control (NC), Diabetic Control (DBC), Normal Xylitol (NXYL) and Diabetic Xylitol (DXYL). T2D was induced in the DBC and DXYL groups. After the confirmation of diabetes, a 10% xylitol solution was supplied instead of drinking water to NXYL and DXYL, while normal drinking water was supplied to NC and DBC ad libitum. After five weeks intervention period, the animals were sacri- ficed and thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH) concentrations as well as superoxide dismutase, catalase glutathione reductase and glutathione peroxidase activities were determined in the liver, heart, kidney, pancreatic tissues and serum samples. Xylitol exhibited significant (p < 0.05) in vitro nitric oxide and hydroxyl radical scavenging and ferric reducing activities. In vivo study revealed significant (p < 0.05) reduction in TBARS concentrations in the xylitol consuming groups compared to their respective controls. Significant (p < 0.05) increase in GSH levels and antioxidant enzyme activities were observed in analyzed tissues and serum of xylitol-fed animals compared to their respective controls. Results of this study indicate that xylitol has strong anti-oxidative potential against T2D-associated oxidative stress. Hence, xylitol can be used as a potential supplement in diabetic foods and food products.
Chika Ifeanyi Chukwuma, Shahidul Islam
2116 related Products with: XYLITOL IMPROVES ANTI-OXIDATIVE DEFENSE SYSTEM IN SERUM, LIVER, HEART, KIDNEY AND PANCREAS OF NORMAL AND TYPE 2 DIABETES MODEL OF RATS.96T0.1 mg 50 UG
#28183644 2016/12/24 To Up
Facile preparation of poly(methylene blue) modified carbon paste electrode for the detection and quantification of catechin.Free radicals are formed as byproducts of metabolism, and are highly unstable due to the presence of unpaired electrons. They readily react with other important cellular components such as DNA causing them damage. Antioxidants such as (+)-catechin (CAT), neutralize free radicals in the blood stream. Hence there is a need for detection and quantification of catechin concentration in various food sources and beverages. Electro-oxidative properties of catechin were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A carbon paste working electrode modified by electropolymerizing methylene blue (MB) was fabricated. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) techniques were used to study the surface morphology of the electrode. Quasi-reversible electron transfer reaction occurred at +0.260V through a diffusion controlled process. In comparison to the bare carbon paste electrode (CPE), there was a significant 5.3 times increment in anodic current sensitivity at the modified electrode at physiological pH. Our findings indicate that for the electro-oxidation of CAT, CPE is a better base material for electropolymerization of MB compared to glassy carbon electrode (GCE). Nyquist plot followed the theoretical shape, indicating low interfacial charge transfer resistance of 0.095kΩ at the modified electrode. Calibration plots obtained by DPV were linear in two ranges of 1.0×10 to 1.0×10 and 1.0×10 to 0.1×10M. The limit of detection (LOD) and limit of quantification (LOQ) was 4.9nM and 14nM respectively. Application of the developed electrode was demonstrated by detecting catechin in green tea and spiked fruit juice with satisfactory recoveries. The sensor was stable, sensitive, selective and reproducible.
G Manasa, Ronald J Mascarenhas, Ashis K Satpati, Ozma J D'Souza, A Dhason
2363 related Products with: Facile preparation of poly(methylene blue) modified carbon paste electrode for the detection and quantification of catechin.100 g 5 G30 Samples 1000 ml per vial2x96 well plate 500 ml 100 G
#27856164 2016/11/06 To Up
Paper-based maskless enzymatic sensor for glucose determination combining ink and wire electrodes.In this work we have developed an amperometric enzymatic biosensor in a paper-based platform with a mixed electrode configuration: carbon ink for the working electrode (WE) and metal wires (from a low-cost standard electronic connection) for reference (RE) and auxiliary electrodes (AE). A hydrophobic wax-defined paper area was impregnated with diluted carbon ink. Three gold-plated pins of the standard connection are employed, one for connecting the WE and the other two acting as RE and AE. The standard connection works as a clip in order to support the paper in between. As a proof-of-concept, glucose sensing was evaluated. The enzyme cocktail (glucose oxidase, horseradish peroxidase and potassium ferrocyanide as mediator of the electron transfer) was adsorbed on the surface. After drying, glucose solution was added to the paper, on the opposite side of the carbon ink. It wets RE and AE, and flows by capillarity through the paper contacting the carbon WE surface. The reduction current of ferricyanide, product of the enzymatic reaction, is measured chronoamperometrically and correlates to the concentration of glucose. Different parameters related to the bioassay were optimized, adhering the piece of paper onto a conventional screen-printed carbon electrode (SPCE). In this way, the RE and the AE of the commercial card were employed for optimizing the paper-WE. After evaluating the assay system in the hybrid paper-SPCE cell, the three-electrode system consisting of paper-WE, wire-RE and wire-AE, was employed for glucose determination, achieving a linear range between 0.3 and 15mM with good analytical features and being able of quantifying glucose in real food samples.
O Amor-Gutiérrez, E Costa Rama, A Costa-García, M T Fernández-Abedul
2346 related Products with: Paper-based maskless enzymatic sensor for glucose determination combining ink and wire electrodes.1,000 tests100tests100Tests1.0 mg100ug100Tests 5 G50 ug 100ul10 mg
#27697653 2016/09/24 To Up
Biosynthesis, characterization and catalytic activity of Cu/RGO/FeO for direct cyanation of aldehydes with K[Fe(CN)].This work reports the green synthesis of the Cu/reduced graphene oxide/FeO (Cu/RGO/FeO) nanocomposite as a new catalytic system for cyanation of aldehydes to nitriles. This nanocomposite catalytic system was synthesized by aqueous extract of leaves of Euphorbia bungei Boiss as a reducing and stabilizing agent. Various substituted aryl nitrile were prepared under optimized conditions and providing moderate to excellent yields. In this process the catalyst exhibited a strong magnet response and could be easily separated by an external magnet and reused with no loss of catalytic activity.
Mahmoud Nasrollahzadeh, Monireh Atarod, S Mohammad Sajadi
2511 related Products with: Biosynthesis, characterization and catalytic activity of Cu/RGO/FeO for direct cyanation of aldehydes with K[Fe(CN)].5 G100 assays25 mg25 μg100μg 1 G96 samples1 ml40 assays10 mg
#27529208 2016/08/13 To Up
Efficient Enzyme-Free Biomimetic Sensors for Natural Phenol Detection.The development of sensors and biosensors based on copper enzymes and/or copper oxides for phenol sensing is disclosed in this work. The electrochemical properties were studied by cyclic and differential pulse voltammetry using standard solutions of potassium ferrocyanide, phosphate/acetate buffers and representative natural phenols in a wide pH range (3.0 to 9.0). Among the natural phenols herein investigated, the highest sensitivity was observed for rutin, a powerful antioxidant widespread in functional foods and ubiquitous in the plant kingdom. The calibration curve for rutin performed at optimum pH (7.0) was linear in a broad concentration range, 1 to 120 µM (r = 0.99), showing detection limits of 0.4 µM. The optimized biomimetic sensor was also applied in total phenol determination in natural samples, exhibiting higher stability and sensitivity as well as distinct selectivity for antioxidant compounds.
Luane Ferreira Garcia, Aparecido Ribeiro Souza, Germán Sanz Lobón, Wallans Torres Pio Dos Santos, Morgana Fernandes Alecrim, Mariângela Fontes Santiago, Rafael Luque Álvarez de Sotomayor, Eric de Souza Gil5L100tests2x96 well plate2.5 mg1x96 well plate100ug5 ml1,000 tests100 ug
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