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https://www.readbyqxmd.com/read/28813104/poly-methylene-blue-modified-electrode-for-indirect-electrochemical-sensing-of-oh-radicals-and-radical-scavengers
#1
Walter A Braun, Bruna C Horn, Lucélia Hoehne, Simone Stülp, Marcelo B DA Rosa, Maurício Hilgemann
A new modified electrode for indirect sensing of OH· and radical scavengers was described. The electrochemical polymerization of methylene blue in aqueous solutions and the properties of the resulting films on a glassy carbon electrode were carried out using cyclic voltammetry. A surface coverage of 1.11 × 109mol cm2 was obtained, revealing a complete surface coverage of the polymeric film on the electrode surface. OH· was able to destroy the poly(methylene blue) film by exposure to a Fenton solution. The loss of the electrochemical signal of the residual polymeric film attached to the electrode surface was related to the extent of its dissolution...
August 14, 2017: Anais da Academia Brasileira de Ciências
https://www.readbyqxmd.com/read/28812233/synthesis-and-photophysical-study-of-new-green-fluorescent-tpa-based-poly-azomethine-s
#2
Naila Khalid, Asma Iqbal, Humaira Masood Siddiqi, O Ok Park
A series of poly(azomethine)s (PAMs) were synthesized from N(1)-(4-aminophenyl)-N(1)-(4-phenoxyphenyl)benzene-1,4-diamine (DA) and various dialdehydes to investigate the influence of structure of polymer chain and triphenylamine-based phenoxy pendant group on the optoelectronic properties. The structural characterization of the resulting poly(azomethine)s was carried out by solubility test, gel permeation chromatography, viscosity measurement, fourier transform infrared (FTIR) spectral and CHN elemental analysis...
August 15, 2017: Journal of Fluorescence
https://www.readbyqxmd.com/read/28809555/electronic-magnetic-and-redox-properties-and-o2-reactivity-of-iron-ii-and-nickel-ii-o-semiquinonate-complexes-of-a-tris-thioether-ligand-uncovering-the-intradiol-cleaving-reactivity-of-an-iron-ii-o-semiquinonate-complex
#3
Peng Wang, Michelle M Killian, Mohamed R Saber, Tian Qiu, Glenn P A Yap, Codrina V Popescu, Joel Rosenthal, Kim R Dunbar, Thomas C Brunold, Charles G Riordan
The iron(II) semiquinonate character within the iron(III) catecholate species has been proposed by numerous studies to account for the O2 reactivity of intradiol catechol dioxygenases, but a well-characterized iron(II) semiquinonate species that exhibits intradiol cleaving reactivity has not yet been reported. In this study, a detailed electronic structure description of the first iron(II) o-semiquinonate complex, [PhTt(tBu)]Fe(phenSQ) [PhTt(tBu) = phenyltris(tert-butylthiomethyl)borate; phenSQ = 9,10-phenanthrenesemiquinonate; Wang et al...
August 15, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28809489/-fefe-hydrogenase-h-cluster-mimics-with-various-s-ch2-ns-linker-lengths-n-2-8-a-systematic-study
#4
Hassan Abul-Futouh, Laith R Almazahreh, Mohammad Kamal Harb, Helmar Görls, Mohammad El-Khateeb, Wolfgang Weigand
The effect of the nature of the dithiolato ligand on the physical and electrochemical properties of synthetic H-cluster mimics of the [FeFe]-hydrogenase is still of significant concern. In this report we describe the cyclization of various alkanedithiols to afford cyclic disulfide, tetrasulfide, and hexasulfide compounds. The latter compounds were used as proligands for the synthesis of a series of [FeFe]-hydrogenase H-cluster mimics having the general formulas [Fe2(CO)6{μ-S(CH2)nS}] (n = 4-8), [Fe2(CO)6{μ-S(CH2)nS}]2 (n = 6-8), and [Fe2(CO)6{(μ-S(CH2)nS)2}] (n = 6-8)...
August 15, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28809114/boolean-logic-tree-of-label-free-dual-signal-electrochemical-aptasensor-system-for-biosensing-three-state-logic-computation-and-keypad-lock-security-operation
#5
Jiao Yang Lu, Xin Xing Zhang, Wei Tao Huang, Qiu Yan Zhu, Xuezhi Ding, Liqiu Xia, Hong Qun Luo, Nian Bing Li
The most serious and yet unsolved problems of molecular logic computing, consist in how to connect molecular events in complex systems into a usable device with specific functions and how to selectively control branchy logic processes from the cascading logic systems. This report demonstrates that Boolean logic tree is utilized to organize and connect "plug and play" chemical events DNA, nanomaterials, organic dye, biomolecule, and denaturant for developing the dual-signal electrochemical evolution aptasensor system with good resettability for amplification detection of thrombin, controllable and selectable three-state logic computation and keypad lock security operation...
August 15, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28808335/direct-electrochemical-measurement-of-metanephrines-in-spot-urine-samples-for-the-diagnosis-of-phaeochromocytomas
#6
Zheng-Hu Shi, Xiao-Qing Zhang, Qian-Na Zhen, Ming Zuo, Gang Tian, Yi-Fan He, Min Ding
Metanephrines (MNs) were suggested as a potential first-line biochemical index for the diagnosis of phaeochromocytomas (PHEO). In this study, we developed a simple electrochemical method for the quantitative measurement of MNs in spot urine samples. As MNs contain a hydroxyphenyl group, they could be oxidized at a certain potential to quinines, which could be further detected by the differential pulse voltammetry (DPV) method using unmodified screen-printed carbon electrode (SPCE). Meanwhile, the solid phase extraction (SPE) technique was used to eliminate the matrix effect in the samples...
August 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28806668/combination-of-electrochemical-biosensor-and-textile-threads-a-microfluidic-device-for-phenol-determination-in-tap-water
#7
F R Caetano, E A Carneiro, D Agustini, L C S Figueiredo-Filho, C E Banks, M F Bergamini, L H Marcolino-Junior
Microfluidic devices constructed using low cost materials presents as alternative for conventional flow analysis systems because they provide advantages as low consumption of reagents and samples, high speed of analysis, possibility of portability and the easiness of construction and maintenance. Herein, is described for the first time the use of an electrochemical biosensor for phenol detection combined with a very simple and efficient microfluidic device based on commercial textile threads. Taking advantages of capillary phenomena and gravity forces, the solution transportation is promoted without any external forces or injection pump...
July 29, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28806657/two-dimensional-metal-chalcogenides-analogous-nise2-nanosheets-and-its-efficient-electrocatalytic-performance-towards-glucose-sensing
#8
Sakthivel Mani, Sukanya Ramaraj, Shen-Ming Chen, Bose Dinesh, Tse-Wei Chen
Recently, 2D layered transition-metal dichalcogenide materials have received great consideration because of their unique electronic properties, large surface area and high electrocatalytic activity. In this connection, for the first time the similar nanostructured material of NiSe2 nanosheets (NiSe2-NS) has been synthesized by a facile hydrothermal method for electrocatalytic applications. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Energy Dispersive X-ray analysis (EDX), X-ray diffraction spectrum (XRD) results confirmed the formation of NiSe2-NS with required stoichiometry and morphology...
August 8, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28806515/redox-triggered-coloration-mechanism-of-electrically-tunable-colloidal-photonic-crystals
#9
Ho-Sung Yang, Jinhyeok Jang, Byoung-Sun Lee, Tae-Hyung Kang, Jong-Jin Park, Woong-Ryeol Yu
Electrically tunable colloidal photonic crystals (ETPCs) have been researched due to several merits such as easy color tunability, no discoloration, and high brightness. The coloration mechanism of ETPCs has been explained by only the electric field. Herein, we report on a new mechanism: electric field plus redox reaction. Imposing electrically conductive or insulated conditions on the electrodes of ETPCs, the coloration behavior of ETPCs was investigated using current-voltage, cyclic voltammetry and zeta potential measurements, as well as scanning electron microscopy...
August 14, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28805869/wrinkle-stabilized-metal-graphene-hybrid-fibers-with-zero-temperature-coefficient-of-resistance
#10
Bo Fang, Jiabin Xi, Yingjun Liu, Fan Guo, Zhen Xu, Weiwei Gao, Daoyou Guo, Peigang Li, Chao Gao
The interfacial adhesion between graphene and metals is poor, as metals tend to generate superlubricity on smooth graphene surface. This problem renders the free assembly of graphene and metals to be a big challenge, and therefore, some desired conducting properties (e.g., stable metal-like conductivities in air, lightweight yet flexible conductors, and ultralow temperature coefficient of resistance, TCR) likely being realized by integrating the merits of graphene and metals remains at a theoretical level. This work proposes a wrinkle-stabilized approach to address the poor adhesion between graphene surface and metals...
August 14, 2017: Nanoscale
https://www.readbyqxmd.com/read/28805866/low-spin-m-ii-l-2-and-m-iii-l-2-m-fe-and-co-complexes-of-tridentate-azo-containing-pyridine-pyrazine-amide-ligands-structures-properties-and-redox-potential-correlations
#11
Arunava Sengupta, Amit Rajput, Suman K Barman, Rabindranath Mukherjee
Using deprotonated forms of tridentate azo-containing pyridine-2-/pyrazine-2-carboxamide 2-[N-(2-phenylazo)carbamoyl]-pyridine/pyrazine, seven bis-ligand complexes of Fe(II)/Co(II) and Fe(III)/Co(III) have been synthesized. Molecular structures of six of them reveal that these six-coordinate complexes utilize all available donor sites of the ligands and assume M(II/III)N2(pyridine/pyrazine)N'2(amide)N''2(azo) coordination. Complexes of Fe(II) and Co(III) are diamagnetic and those of Fe(III) and Co(II) are paramagnetic (S = 1/2; room-temperature magnetic data and EPR spectra)...
August 14, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28805817/room-temperature-current-blockade-in-atomically-defined-single-cluster-junctions
#12
Giacomo Lovat, Bonnie Choi, Daniel W Paley, Michael L Steigerwald, Latha Venkataraman, Xavier Roy
Fabricating nanoscopic devices capable of manipulating and processing single units of charge is an essential step towards creating functional devices where quantum effects dominate transport characteristics. The archetypal single-electron transistor comprises a small conducting or semiconducting island separated from two metallic reservoirs by insulating barriers. By enabling the transfer of a well-defined number of charge carriers between the island and the reservoirs, such a device may enable discrete single-electron operations...
August 14, 2017: Nature Nanotechnology
https://www.readbyqxmd.com/read/28804798/probing-biological-redox-chemistry-with-large-amplitude-fourier-transformed-ac-voltammetry
#13
Hope Adamson, Alan M Bond, Alison Parkin
Biological electron-exchange reactions are fundamental to life on earth. Redox reactions underpin respiration, photosynthesis, molecular biosynthesis, cell signalling and protein folding. Chemical, biomedical and future energy technology developments are also inspired by these natural electron transfer processes. Further developments in techniques and data analysis are required to gain a deeper understanding of the redox biochemistry processes that power Nature. This review outlines the new insights gained from developing Fourier transformed ac voltammetry as a tool for protein film electrochemistry...
August 14, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28803479/design-of-cyclic-peptides-based-glucose-receptors-and-their-application-in-glucose-sensing
#14
Chao Li, Xin Chen, Fuyuan Zhang, Xingxing He, Guozhen Fang, Jifeng Liu, Shuo Wang
Glucose assay is of great scientific significance in clinical diagnostics and bioprocess monitoring and to design new glucose receptor is necessary for development of more sensitive, selective and robust glucose detection techniques. Herein, a series of cyclic peptides (CPs) glucose receptor were designed to mimic the binding sites of glucose binding protein (GBP) and CPs' sequence contained amino acid sites Asp, Asn, His, Asp, Arg, which constituted the first layer interactions of GBP. The properties of these CPs used as a glucose receptor or substitute for the GBP were studied by using quartz crystal microbalance (QCM) technique...
August 14, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28803164/electrochemically-active-microorganisms-from-an-acid-mine-drainage-affected-site-promote-cathode-oxidation-in-microbial-fuel-cells
#15
Claudia Rojas, Ignacio T Vargas, Mary Ann Bruns, John M Regan
The limited database of acidophilic or acidotolerant electrochemically active microorganisms prevents advancements on microbial fuel cells (MFCs) operated under low pH. In this study, three MFCs were used to enrich cathodic biofilms using acid mine drainage (AMD) sediments as inoculum. Linear sweep voltammetry showed cathodic current plateaus of 5.5 (±0.7) mA at about -170mV vs Ag/AgCl and 8.5 (±0.9) mA between -500mV to -450mV vs Ag/AgCl for biofilms developed on small graphite fiber brushes. After gamma irradiation, biocathodes exhibited a decrease in current density approaching that of abiotic controls...
August 3, 2017: Bioelectrochemistry
https://www.readbyqxmd.com/read/28802177/dna-biosensors-based-on-gold-nanoparticles-modified-graphene-oxide-for-the-detection-of-breast-cancer-biomarkers-for-early-diagnosis
#16
Ayman Ali Saeed, Josep Lluís Acero Sánchez, Ciara K O'Sullivan, Mohammed Nooredeen Abbas
Two different DNA (ERBB2c and CD24c) modified gold nanoparticles and graphene oxide loaded on glassy carbon electrodes were prepared for early detection of breast cancer markers by electrochemical detection of HER2. Comparative study of ERBB2c and CD24c for the detection was carried out. A "sandwich-type" detection strategy was employed in this electrochemical DNA biosensor and its response was measured by amperometric detection. The electrochemical signal enhancement achieved via gold nanoparticles and grapheme oxide system allowed for sensitive detection of the breast cancer biomarker ERBB2 and the control marker CD24...
July 14, 2017: Bioelectrochemistry
https://www.readbyqxmd.com/read/28801614/palladium-nanoparticles-entrapped-in-a-self-supporting-nanoporous-gold-wire-as-sensitive-dopamine-biosensor
#17
Xin Yi, Yuxuan Wu, Guoxin Tan, Peng Yu, Lei Zhou, Zhengnan Zhou, Junqi Chen, Zhengao Wang, Jinshan Pang, Chengyun Ning
Traced dopamine (DA) detection is critical for the early diagnosis and prevention of some diseases such as Parkinson's, Alzheimer and schizophrenia. In this research, a novel self-supporting three dimensional (3D) bicontinuous nanoporous electrochemical biosensor was developed for the detection of dopamine by Differential Pulse Voltammetry (DPV). This biosensor was fabricated by electrodepositing palladium nanoparticles (Pd) onto self-supporting nanoporous gold (NPG) wire. Because of the synergistic effects of the excellent catalytic activity of Pd and novel structure of NPG wire, the palladium nanoparticles decorated NPG (Pd/NPG) biosensor possess tremendous superiority in the detection of DA...
August 11, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28800098/porous-graphene-oxide-prepared-on-nickel-foam-by-electrophoretic-deposition-and-thermal-reduction-as-high-performance-supercapacitor-electrodes
#18
Yunhe Xu, Jun Li, Wenxin Huang
A simple electrophoretic deposition method was developed to prepare graphene oxide (GO) films on the frameworks of nickel foam without any conductive agents and polymer binders. Then, GO was transformed into thermally-reduced graphene oxide (RGO) at an appropriate temperature. The effects of deposition voltage and thermal reduction temperature on the electrochemical properties of RGO were investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge. The appropriate combination of deposition voltage and thermal reduction temperature was established...
August 11, 2017: Materials
https://www.readbyqxmd.com/read/28798991/a-highly-sensitive-electrochemical-dna-biosensor-from-acrylic-gold-nano-composite-for-the-determination-of-arowana-fish-gender
#19
Mahbubur Rahman, Lee Yook Heng, Dedi Futra, Chew Poh Chiang, Zulkafli A Rashid, Tan Ling Ling
The present research describes a simple method for the identification of the gender of arowana fish (Scleropages formosus). The DNA biosensor was able to detect specific DNA sequence at extremely low level down to atto M regimes. An electrochemical DNA biosensor based on acrylic microsphere-gold nanoparticle (AcMP-AuNP) hybrid composite was fabricated. Hydrophobic poly(n-butylacrylate-N-acryloxysuccinimide) microspheres were synthesised with a facile and well-established one-step photopolymerization procedure and physically adsorbed on the AuNPs at the surface of a carbon screen printed electrode (SPE)...
August 10, 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28798337/the-laccase-like-reactivity-of-manganese-oxide-nanomaterials-for-pollutant-conversion-rate-analysis-and-cyclic-voltammetry
#20
Xinghao Wang, Jiaoqin Liu, Ruijuan Qu, Zunyao Wang, Qingguo Huang
Nanostructured manganese oxides, e.g. MnO2, have shown laccase-like catalytic activities, and are thus promising for pollutant oxidation in wastewater treatment. We have systematically compared the laccase-like reactivity of manganese oxide nanomaterials of different crystallinity, including α-, β-, γ-, δ-, and ɛ-MnO2, and Mn3O4, with 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) and 17β-estradiol (E2) as the probing substrates. The reaction rate behaviors were examined with regard to substrate oxidation and oxygen reduction to evaluate the laccase-like catalysis of the materials, among which γ-MnO2 exhibits the best performance...
August 10, 2017: Scientific Reports
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