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https://www.readbyqxmd.com/read/28629040/3-aminopropyltrimethoxysilane-mediated-solvent-induced-synthesis-of-gold-nanoparticles-for-biomedical-applications
#1
Prem C Pandey, Gunjan Pandey, Alain Walcarius
The effect of acetone on 3-aminopropyltrimethoxysilane (3-APTMS) mediated synthesis of gold nanoparticles (AuNPs) in polar protic, polar aprotic and non polar solvents specifically water, acetone and chloroform has been studied. The findings revealed that acetone promotes the formation of siloxane polymer in chloroform and acetone solvents, but not in water, while AuNPs are formed in all cases. The bifunctional nature of 3-APTMS [NH2(CH2)3Si(OMe)3] controls the formation of siloxane polymer through hydrolysis and condensation of trimethoxysilyl group whereas the amine moieties are likely to form imine linkage, which are involved in the synthesis of gold nanoparticles...
October 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28627895/electroanalytical-assessment-of-the-effect-of-ni-fe-stoichiometry-and-architectural-expression-on-the-bifunctional-activity-of-nanoscale-niyfe1-yox
#2
Jesse S Ko, Christopher N Chervin, Mallory N Vila, Paul A DeSario, Joseph F Parker, Jeffrey W Long, Debra R Rolison
Electrocatalysis of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) was assessed for a series of Ni-substituted ferrites (NiyFe1-yOx, where y = 0.1 to 0.9) as expressed in porous, high-surface-area forms (ambigel and aerogel nanoarchitectures). We then correlate electrocatalytic activity with Ni:Fe stoichiometry as a function of surface area, crystallite size, and free volume. In order to ensure in-series comparisons, calcination at 350 °C/air was necessary to crystallize the respective NiyFe1-yOx nanoarchitectures, which index to the inverse spinel structure for Fe-rich materials (y ≤ 0...
June 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28621385/electroanalytical-determination-of-escitalopram-oxalate-using-nickel-nanoparticles-modified-carbon-paste-sensor
#3
Kamal Attia, A Mona Mohamed, M Amany Fekry
A sensitive voltammetric method was described for the determination of escitalopram oxalate based on electrocatalytic oxidation at nickel nanoparticles modified chloranil carbon paste sensor in Britton-Robinson buffer (pH range from 2 to 10). The modified electrode was characterized by scanning electron microscopy, electrochemical impedance and cyclic voltammetry. The investigation of electrochemical behavior of escitalopram oxalate was performed using cyclic voltammetry and differential pulse voltammetry. The anodic peak current showed a linear range from 1...
June 2017: Acta Chimica Slovenica
https://www.readbyqxmd.com/read/28621134/surfactant-and-binder-free-hierarchical-platinum-nanoarrays-directly-grown-onto-a-carbon-felt-electrode-for-efficient-electrocatalysis
#4
Widya Ernayati Kosimaningrum, Thi-Xuan-Huong Le, Yaovi Holade, Mikhael Bechelany, Sophie Tingry, Buchari Buchari, Indra Noviandri, Christophe Innocent, Marc Cretin
The future of fuel cells that convert the chemical energy to electricity relies mostly on the efficiency of oxygen reduction reaction (ORR) due to its sluggish kinetics. By effectively bypassing the use of organic surfactants, post-synthesis steps for the immobilization onto electrodes, the catalytic inks preparation using binders, and the common problem of nanoparticles detachment from supports involved in traditional methodologies, we demonstrate a versatile electrodeposition method for growing anisotropic microstructures directly onto a three-dimensional (3D) carbon felt electrode, using platinum nanoparticles as elementary building blocks...
June 16, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28579929/microfabricated-massive-electrochemical-arrays-of-uniform-ultramicroelectrodes
#5
Christopher Gunderson, Bo Zhang
We report the preparation and electrochemical characterization of massive electrochemical arrays containing as many as 110,000 highly uniform ultramicroelectrodes (UMEs). These arrays were microfabricated using conventional photolithography techniques on a gold-coated silicon chip in a simple three-step method. Photoresist polymer was used as an effective insulating matrix to define 2 μm, 3 μm, and 4 μm diameter circular UMEs across a 1 × 1 mm(2) area. The UME arrays are high uniform and contain tens of thousands of active disk-shape UMEs slightly recessed in thin films of photoresist...
November 15, 2016: Journal of Electroanalytical Chemistry
https://www.readbyqxmd.com/read/28548867/statins-determination-a-review-of-electrochemical-techniques
#6
I Antal, M Koneracka, V Zavisova, M Kubovcikova, Zh Kormosh, P Kopcansky
The use of electroanalytical techniques for the determination of statins (Atorvastatin, Fluvastatin, Lovastatin, Pitavastatin, Pravastatin, Rosuvastatin and Simvastatin) is reviewed covering the period from 1997 to 2016. Among all of the published electrochemical methods, voltammetry and polarography are the most popular techniques for determination of statins and both are used for the analysis of pharmaceutical dosage forms and biological samples. Determination of statins by potentiometric method using ion-selective electrodes is reported in only few papers...
May 26, 2017: Critical Reviews in Analytical Chemistry
https://www.readbyqxmd.com/read/28507703/advanced-electroanalytical-chemistry-at-nanoelectrodes
#7
Yi-Lun Ying, Zhifeng Ding, Dongping Zhan, Yi-Tao Long
Nanoelectrodes, with dimensions below 100 nm, have the advantages of high sensitivity and high spatial resolution. These electrodes have attracted increasing attention in various fields such as single cell analysis, single-molecule detection, single particle characterization and high-resolution imaging. The rapid growth of novel nanoelectrodes and nanoelectrochemical methods brings enormous new opportunities in the field. In this perspective, we discuss the challenges, advances, and opportunities for nanoelectrode fabrication, real-time characterizations and high-performance electrochemical instrumentation...
May 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28501185/simultaneous-voltammetric-determination-of-vanillin-and-caffeine-in-food-products-using-an-anodically-pretreated-boron-doped-diamond-electrode-its-comparison-with-hplc-dad
#8
Hoshyar Saadi Ali, Abdullah A Abdullah, Pınar Talay Pınar, Yavuz Yardım, Zühre Şentürk
This paper describes an electroanalytical method for the simultaneous determination of vanillin (VAN) and caffeine (CAF) using an anodically pretreated boron-doped diamond electrode. Selective determination of one compound in the presence of other one was also realized. Both compounds yielded a single irreversible oxidation peak using cyclic voltammetry. The nature of the electrode reaction was found to be diffusion controlled with contribution of adsorption. By using square-wave adsorptive stripping voltammetry after 60s accumulation under open-circuit voltage, method allowed simultaneous determination of VAN and CAF in phosphate buffer, pH 2...
August 1, 2017: Talanta
https://www.readbyqxmd.com/read/28492640/impedimetric-measurement-of-dna-dna-hybridisation-using-microelectrodes-with-different-radii-for-detection-of-methicillin-resistant-staphylococcus-aureus-mrsa
#9
Poh Quan Li, Andrew Piper, Ilka Schmueser, Andrew R Mount, Damion K Corrigan
Due to their electroanalytical advantages, microelectrodes are a very attractive technology for sensing and monitoring applications. One highly important application is measurement of DNA hybridisation to detect a wide range of clinically important phenomena, including single nucleotide polymorphisms (SNPs), mutations and drug resistance genes. The use of electrochemical impedance spectroscopy (EIS) for measurement of DNA hybridisation is well established for large electrodes but as yet remains relatively unexplored for microelectrodes due to difficulties associated with electrode functionalisation and impedimetric response interpretation...
May 11, 2017: Analyst
https://www.readbyqxmd.com/read/28448855/glassy-carbon-electrode-modified-with-7-7-8-8-tetracyanoquinodimethane-and-graphene-oxide-triggered-a-synergistic-effect-low-potential-amperometric-detection-of-reduced-glutathione
#10
Baiqing Yuan, Chunying Xu, Renchun Zhang, Donghui Lv, Sujuan Li, Daojun Zhang, Lin Liu, Carlos Fernandez
A sensitive electrochemical sensor based on the synergistic effect of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and graphene oxide (GO) for low-potential amperometric detection of reduced glutathione (GSH) in pH 7.2 phosphate buffer solution (PBS) has been reported. This is the first time that the combination of GO and TCNQ have been successfully employed to construct an electrochemical sensor for the detection of glutathione. The surface of the glassy carbon electrode (GCE) was modified by a drop casting using TCNQ and GO...
April 21, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28426249/non-enzymatic-electrochemistry-in-characterization-and-analysis-of-steroid-compounds
#11
Jan Klouda, Jiří Barek, Karel Nesměrák, Karolina Schwarzová-Pecková
This review summarizes achievements in electrochemistry-related research of steroid-based compounds in clinical, pharmaceutical, and environmental analysis. Special attention is paid to compounds possessing none or only isolated double bonds at the steroid core. Their direct redox activity is limited to far positive/negative potentials under variety of conditions and electrode materials and relies on the functional groups attached to the steroid skeleton, or as the case may be its double bond or moieties present at the side chain...
April 20, 2017: Critical Reviews in Analytical Chemistry
https://www.readbyqxmd.com/read/28418648/modular-flow-through-platform-for-spectroelectrochemical-analysis
#12
Tomer Noyhouzer, Michael E Snowden, Ushula M Tefashe, Janine Mauzeroll
A new type of flow platform for electrochemical and spectroelectrochemical measurements is presented. Finite element method simulations confirm that the hydrodynamic profile within the device is not turbulent and provides an analytical platform for the investigation of homogeneous kinetics, radical lifetimes, and reaction mechanisms. The modular "plug and play" configuration of the platform allows one to carry out electrochemistry and spectroscopy individually or simultaneously. Specific demonstrations of electroanalytical measurements using the flow system platform includes voltammetric analysis of organometallic compounds and quantitative analysis of ascorbic acid in commercial orange juice samples...
April 28, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28418064/surfactant-exfoliated-2d-hexagonal-boron-nitride-2d-hbn-explored-as-a-potential-electrochemical-sensor-for-dopamine-surfactants-significantly-influence-sensor-capabilities
#13
Aamar F Khan, Dale A C Brownson, Christopher W Foster, Graham C Smith, Craig E Banks
Surfactant exfoliated 2D hexagonal Boron Nitride (2D-hBN) nanosheets are explored as a potential electrochemical sensing platform and evaluated towards the electroanalytical sensing of dopamine (DA) in the presence of the common interferents, ascorbic acid (AA) and uric acid (UA). Surfactant exfoliated 2D-hBN nanosheets (2-4 layers) fabricated using sodium cholate in aqueous media are electrically wired via a drop-casting modification process onto disposable screen-printed graphite electrodes (SPEs). We critically evaluate the performance of these 2D-hBN modified SPEs and demonstrate the effect of 'mass coverage' towards the detection of DA, AA and UA...
April 18, 2017: Analyst
https://www.readbyqxmd.com/read/28394410/nanotechnology-for-electroanalytical-biosensors-of-reactive-oxygen-and-nitrogen-species
#14
REVIEW
Rajesh Seenivasan, Charles Kolodziej, Chandran Karunakaran, Clemens Burda
Over the past several decades, nanotechnology has contributed to the progress of biomedicine, biomarker discovery, and the development of highly sensitive electroanalytical / electrochemical biosensors for in vitro and in vivo monitoring, and quantification of oxidative and nitrosative stress markers like reactive oxygen species (ROS) and reactive nitrogen species (RNS). A major source of ROS and RNS is oxidative stress in cells, which can cause many human diseases, including cancer. Therefore, the detection of local concentrations of ROS (e...
April 10, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
https://www.readbyqxmd.com/read/28391695/simulation-based-approach-to-determining-electron-transfer-rates-using-square-wave-voltammetry
#15
Philippe Dauphin-Ducharme, Netzahualcóyotl Arroyo-Currás, Martin Kurnik, Gabriel Ortega, Hui Li, Kevin W Plaxco
The efficiency with which square-wave voltammetry differentiates faradic and charging currents makes it a particularly sensitive electroanalytical approach, as evidenced by its ability to measure nanomolar or even picomolar concentrations of electroactive analytes. Because of the relative complexity of the potential sweep it uses, however, the extraction of detailed kinetic and mechanistic information from square-wave data remains challenging. In response, we demonstrate here a numerical approach by which square-wave data can be used to determine electron transfer rates...
May 9, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28390317/a-highly-sensitive-and-selective-sensor-based-on-a-graphene-coated-carbon-paste-electrode-modified-with-a-computationally-designed-boron-embedded-duplex-molecularly-imprinted-hybrid-membrane-for-the-sensing-of-lamotrigine
#16
Hongjuan Wang, Duo Qian, Xilin Xiao, Shuqin Gao, Jianlin Cheng, Bo He, Lifu Liao, Jian Deng
An innovative electrochemical sensor, based on a carbon paste electrode (CPE) modified with graphene (GR) and a boron-embedded duplex molecularly imprinted hybrid membrane (B-DMIHM), was fabricated for the highly sensitive and selective determination of lamotrigine (LMT). Density functional theory (DFT) was employed to study the interactions between the template and monomers to screen appropriate functional monomers for rational design of the B-DMIHM. The distinct synergic effect of GR and B-DMIHM was evidenced by the positive shift of the reduction peak potential of LMT at B-DMIHM/GR modified CPE (B-DMIHM/GR/CPE) by about 300mV, and the 13-fold amplification of the peak current, compared to a bare carbon paste electrode (CPE)...
March 30, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28372223/determination-of-vitamin-e-in-margarines-and-edible-oils-using-square-wave-anodic-stripping-voltammetry-with-a-glassy-carbon-paste-electrode
#17
Milan Sýs, Blanka Švecová, Ivan Švancara, Radovan Metelka
A new electroanalytical method for determination of vitamin E in the form of the total content of tocopherols present in margarines and edible oils has been developed. The method is based on extraction of these biologically active compounds into silicone oil, acting as lipophilic binder of glassy carbon paste electrode, with subsequent electrochemical detection by square wave anodic stripping voltammetry (SWASV) in 0.1M HNO3. The values of vitamin E contents were expressed as mass equivalent of α-tocopherol known as the most active form of this lipophilic vitamin...
August 15, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28344364/improved-electroanalytical-characteristics-for-flumetralin-determination-in-the-presence-of-surface-active-compound
#18
Dariusz Guziejewski, Sylwia Smarzewska, Radovan Metelka, Agnieszka Nosal-Wiercińska, Witold Ciesielski
ABSTRACT: The use of square wave voltammetry (SWV) and square wave adsorptive stripping voltammetry (SWAdSV) in conjunction with a cyclic renewable silver amalgam film electrode for the determination of flumetralin is presented. Poor separation of two overlapped reduction peaks is significantly improved when hexadecyltrimethylammonium bromide is used as a component of the supporting electrolyte solution (together with BR buffer pH 9.5). The SW technique parameters were investigated and found optimal as follows: frequency 50 Hz, amplitude 40 mV, and step potential 5 mV...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28342847/na-k-atpase-interaction-with-methylglyoxal-as-reactive-metabolic-side-product
#19
Marika Svrckova, Martina Zatloukalova, Petra Dvorakova, Dominika Coufalova, David Novak, Lenka Hernychova, Jan Vacek
Proteins are subject to oxidative modification and the formation of adducts with a broad spectrum of reactive species via enzymatic and non-enzymatic mechanisms. Here we report that in vitro non-enzymatic methylglyoxal (MGO) binding causes the inhibition and formation of MGO advanced glycation end-products (MAGEs) in Na(+)/K(+)-ATPase (NKA). Concretely, MGO adducts with NKA amino acid residues (mainly Arg) and N(ε)-(carboxymethyl)lysine (CML) formation were found. MGO is not only an inhibitor for solubilized NKA (IC50=91±16μM), but also for reconstituted NKA in the lipid bilayer environment, which was clearly demonstrated using a DPPC/DPPE liposome model in the presence or absence of the NKA-selective inhibitor ouabain...
March 22, 2017: Free Radical Biology & Medicine
https://www.readbyqxmd.com/read/28342426/optical-and-electrochemical-dual-channel-sensing-of-cu-2-using-functionalized-furo-2-3-d-pyrimidines-2-4-1h-3h-diones
#20
Manoj Kumar, Lokesh Kumar Kumawat, Priyanka Bhatt, Anjali Jha, Shilpi Agarwal, Anuj Sharma, Vinod Kumar Gupta
Owing to their easy accessibility and high degree of structural and functional diversity, many multicomponent reactions (MCRs) have been a rich source of conjugate π-systems, functionalised chromophores (or fluorophore) and redox active molecules. Despite their high explorative potential and practical benefits, only a few MCR products have been so far investigated for their metal sensing abilities. In the present report, two furopyrimidinones (FPys) based molecular systems have been synthesized by [4+1] cycloaddition based MCR sequence...
March 18, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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