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Preetha Jothimuthu, Joe L Hsu, Robert Chen, Mohammed Inayathullah, Venkata Raveendra Pothineni, Antony Jan, Geoffrey C Gurtner, Jayakumar Rajadas, Mark R Nicolls
Iron plays an especially important role in human physiological functions and pathological impairments. The superior properties of carbon nanotubes (CNTs) and their modification with bismuth and magnetic nanoparticles as developed in this work have led to an extraordinary and novel material to facilitate ultrasensitive detection in the nanomolar range. Here, we present the development of an electrochemical sensor for detection of ferrous (Fe(2+)) and ferric (Fe(3+)) iron by means of CNTs modified with bismuth and magnetic nanoparticles for higher sensitivity of detection...
September 2016: ChemNanoMat: Chemistry of Nanomaterials for Energy, Biology and More
Qi Xiao, Shuangyan Lu, Chusheng Huang, Wei Su, Shan Huang
Based on N-doped carbon dots/β-cyclodextrin nanocomposites modified glassy carbon electrodes (N-CDs/β-CD/GCE), an effective electrochemical sensor for enantioselective recognition of tryptophan (Trp) enantiomers was developed by differential pulse voltammograms (DPVs). Fluorescent N-CDs were synthesized through a hydrothermal method and characterized by spectroscopic approaches. The N-CDs/β-CD nanocomposites were efficiently electrodeposited on the surface of GCE through C-N bond formation between N-CDs and electrode...
November 9, 2016: Sensors
Seda Uzunboy, Sema Demirci Çekiç, Ece Eksin, Arzum Erdem, Reşat Apak
An unbalanced excess of oxygen/nitrogen species (ROS/RNS) can give oxidative hazard to DNA and other biomacromolecules under oxidative stress conditions. While the 'comet' assay for measuring DNA damage is neither specific nor practical, monitoring oxidative changes on individual DNA bases and other oxidation products needs highly specialized equipment and operators. Thus, we developed a modified CUPRAC (cupric ion reducing antioxidant capacity) colorimetric method to determine the average total damage on DNA produced by Fenton oxidation, taking advantage of the fact that the degradation products of DNA but not the original macromolecule is CUPRAC-responsive...
November 2, 2016: Analytical Biochemistry
Mojtaba Jahanbakhshi
Mesoporous carbon foam (MCF) with particular properties was prepared via a simplistic and template-free procedure. The synthesized MCF was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction and BET surface area techniques. Porous MCF with pores diameters of 5 to 10nm provided a perfect substrate including extensive specific surface area to modify the electrodes surface. The obtained MCF was dispersed in Salep solution to prepare a stable suspension (S-MCF)...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
M Antonietta Baldo, Paolo Oliveri, Remo Simonetti, Salvatore Daniele
In this paper, a novel voltammetric/amperometric approach for the direct determination of free acidity (FFA, expressed as mass percentage of free oleic acid) in olive oil samples is presented. The method is based on the reduction processes occurring at a platinum microdisk electrode involving the free fatty acids present in the matrices. To overcome problems related to the low conductivity of the samples investigated, olive oils were mixed with suitable amounts of the room temperature ionic liquid (RTIL), tri-hexyl(tetradecyl)phosphonium bis (trifluoromethylsulfonyl) imide ([P14,6,6,6](+)[NTf2](-)), which acted as a supporting electrolyte...
December 1, 2016: Talanta
Huichao Li, Lu Wang, Kai Sheng, Lina Zou, Baoxian Ye
The nanocomposites of titanium dioxide nanoparticles decorated poly(diallyldimethylammonium chloride)-functionalized graphene (TiO2-PDDA-Gr) were successfully synthesized via a facile and green strategy. The prepared nanocomposites were characterized by X-ray diffraction (XRD), UV-visible spectrophotometry (UV-vis), Fourier Transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM). By combining the merits of the PDDA-Gr and TiO2 NPs, a highly sensitive electrochemical sensor was erected to detect esculetin based on the TiO2-PDDA-Gr nanocomposites...
December 1, 2016: Talanta
Carlos A Teixeira, Gabriela Furlan Giordano, Maisa B Beltrame, Luis Carlos Silveira Vieira, Angelo Luiz Gobbi, Renato Sousa Lima
The contamination, passivation, or fouling of the detection electrodes is a serious problem undermining the analytical performance of electroanalytical devices. The methods to regenerate the electrochemical activity of the solid electrodes involve mechanical, physical, or chemical surface treatments that usually add operational time, complexity, chemicals, and further instrumental re-quirements to the analysis. In this paper, we describe for the first time a reproducible method for renewing solid electrodes when-ever their morphology or composition are non-specifically changed without any surface treatment...
October 17, 2016: Analytical Chemistry
David Polcari, Philippe Dauphin-Ducharme, Janine Mauzeroll
Scanning electrochemical microscopy (SECM) is an electroanalytical scanning probe technique capable of imaging substrate topography and local reactivity with high resolution. Since its inception in 1989, it has expanded into a wide variety of research areas including biology, corrosion, energy, kinetics, instrumental development, and surface modification. In the past 25 years, over 1800 peer-reviewed publications have focused on SECM, including several topical reviews. However, these reviews often omit key details, forcing readers to search the literature...
October 13, 2016: Chemical Reviews
Todd J Anderson, Bo Zhang
Metal nanoparticles are key electrode materials in a variety of electrochemical applications including basic electron-transfer study, electrochemical sensing, and electrochemical surface enhanced Raman spectroscopy (SERS). Metal nanoparticles have also been extensively applied to electrocatalytic processes in recent years due to their high catalytic activity and large surface areas. Because the catalytic activity of metal nanoparticle is often highly dependent on their size, shape, surface ligands, and so forth, methods for examining and better understanding the correlation between particle structure and function are of great utility in the development of more efficient catalytic systems...
October 12, 2016: Accounts of Chemical Research
Hui Zhang, Huilei Dong, Guoqing Yang, Hongfei Chen, Chenxin Cai
Effective detection of DNA methyltransferase (DNMT) activity is significant for cancer research. Herein, we developed a sensitive electroanalytical method to detect human DNA (cytosine-5)-methyltransferase1 (DNMT1) from crude lysates of cancer cells. In this assay, capture DNA having a preferred DNMT1 methylation site was immobilized on a gold electrode, then hybridized with gold nanoparticle (Au NP)-DNA complexes. The modified electrodes were equilibrated with the lysate, and then incubated with methylation-sensitive restriction enzyme...
October 12, 2016: Analytical Chemistry
Mahiar M Hamedi, Barış Ünal, Emily Kerr, Ana C Glavan, M Teresa Fernandez-Abedul, George M Whitesides
This communication describes the use of uncoated cellophane (regenerated cellulose films) for the fabrication of microplates, and the use of coated cellophane for the fabrication of open-channel microfluidic devices. The microplates based on uncoated cellophane are particularly interesting for applications that require high transparency in the ultraviolet (UV) regime, and offer a low-cost alternative to expensive quartz-well plates. Uncoated cellophane is also resistant to damage by various solvents. The microfluidic devices, based on coated cellophane, can have features with dimensions as small as 500 μm, and complex, non-planar geometries...
October 5, 2016: Lab on a Chip
Romana Jarošová, Joy Rutherford, Greg M Swain
We report on the analytical performance of a tetrahedral amorphous carbon (ta-C:N) thin-film electrode in flow injection analysis with amperometric detection. Two model redox analytes were used to evaluate the electrode response because of their positive detection potentials and propensity (i.e., reaction products) to adsorb and foul sp(2) carbon electrodes: tyrosine and tryptophan. ta-C:N electrodes are attractive for electroanalytical applications because they possesses many of the excellent properties of boron-doped nanocrystalline diamond (BDD) and they can be deposited at or near room temperature...
October 17, 2016: Analyst
Norazriena Yusoff, Perumal Rameshkumar, Muhammad Shahid Mehmood, Alagarsamy Pandikumar, Hing Wah Lee, Nay Ming Huang
A sensitive and novel electrochemical sensor was developed for the detection of hydrogen peroxide (H2O2) using a reduced graphene oxide-nafion@silver6 (rGO-Nf@Ag6) nanohybrid modified glassy carbon electrode (GC/rGO-Nf@Ag6). The GC/rGO-Nf@Ag6 electrode exhibited an excellent electrochemical sensing ability for determining H2O2 with high sensitivity and selectivity. The detection limit of the electrochemical sensor using the GC/rGO-Nf@Ag6 electrode for H2O2 determination was calculated to be 5.35×10(-7)M with sensitivity of 0...
September 14, 2016: Biosensors & Bioelectronics
Isaac Yves Lopes de Macêdo, Luane Ferreira Garcia, Jerônimo Raimundo Oliveira Neto, Karla Carneiro de Siqueira Leite, Valdir Souza Ferreira, Paulo César Ghedini, Eric de Souza Gil
Red fruits are rich sources of antioxidant compounds with recognized health benefits. Since they are perishable, dried extracts emerge as more durable products and their quality control must include antioxidant capacity assays. In this study, the redox behavior of commercial dried products obtained from camu-camu, açai, acerola and cranberry red fruits was evaluated by electroanalytical approaches. The antioxidant potential was determined by 2,2-diphenyl-1-picrylhydrazyl free radical assay and the electrochemical index concept...
February 15, 2017: Food Chemistry
Aamar F Khan, Dale A C Brownson, Edward P Randviir, Graham C Smith, Craig E Banks
Crystalline 2D hexagonal boron nitride (2D-hBN) nanosheets are explored as a potential electrocatalyst toward the electroanalytical sensing of dopamine (DA). The 2D-hBN nanosheets are electrically wired via a drop-casting modification process onto a range of commercially available carbon supporting electrodes, including glassy carbon (GC), boron-doped diamond (BDD), and screen-printed graphitic electrodes (SPEs). 2D-hBN has not previously been explored toward the electrochemical detection/electrochemical sensing of DA...
October 4, 2016: Analytical Chemistry
Huidi Tian, Lu Wang, Zdenek Sofer, Martin Pumera, Alessandra Bonanni
Doping graphene with heteroatoms can alter the electronic and electrochemical properties of the starting material. Contrasting properties should be expected when the doping is carried out with electron donating species (n-type dopants) or with electron withdrawing species (p-type dopants). This in turn can have a profound influence on the electroanalytical performance of the doped material being used for the detection of specific probes. Here we investigate the electrochemical oxidation of DNA bases adenine, guanine, thymine and cytosine on two heteroatom-doped graphene platforms namely boron-doped graphene (p-type dopant) and nitrogen-doped graphene (n-type dopant)...
2016: Scientific Reports
Amadou L Ndiaye, Sébastien Delile, Jérôme Brunet, Christelle Varenne, Alain Pauly
Here, we report on the use of electrochemical methods for the detection of volatiles fatty acids (VFAs), namely acetic acid. We used tetra-tert-butyl phthalocyanine (PcH₂-tBu) as the sensing material and investigated its electroanalytical properties by means of cyclic voltammetry (CV) and square wave voltammetry (SWV). To realize the electrochemical sensing system, the PcH₂-tBu has been dropcast-deposited on carbon (C) orgold (Au)screen-printed electrodes (SPEs) and characterized by cyclic voltammetry and scanning electron microscopy (SEM)...
September 1, 2016: Biosensors
François Patou, Fatima AlZahra'a Alatraktchi, Claus Kjægaard, Maria Dimaki, Jan Madsen, Winnie E Svendsen
The association of smart mobile devices and lab-on-chip technologies offers unprecedented opportunities for the emergence of direct-to-consumer in vitro medical diagnostics applications. Despite their clear transformative potential, obstacles remain to the large-scale disruption and long-lasting success of these systems in the consumer market. For instance, the increasing level of complexity of instrumented lab-on-chip devices, coupled to the sporadic nature of point-of-care testing, threatens the viability of a business model mainly relying on disposable/consumable lab-on-chips...
September 3, 2016: Diagnostics
José A Ribeiro, Paula M V Fernandes, Carlos M Pereira, F Silva
This work describes the state of the art of electrochemical devices for the detection of an important class of neurotransmitters: the catecholamines. This class of biogenic amines includes dopamine, noradrenaline (also called norepinephrine) and adrenaline (also called epinephrine). Researchers have focused on the role of catecholamine molecules within the human body because they are involved in many important biological functions and are commonly associated with several diseases, such as Alzheimer's and Parkinson...
November 1, 2016: Talanta
Yunshan Fan, Chu Han, Bo Zhang
Nanoelectrodes have key advantages compared to electrodes of conventional size and are the tool of choice for numerous applications in both fundamental electrochemistry research and bioelectrochemical analysis. This Minireview summarizes recent advances in the development, characterization, and use of nanoelectrodes in nanoscale electroanalytical chemistry. Methods of nanoelectrode preparation include laser-pulled glass-sealed metal nanoelectrodes, mass-produced nanoelectrodes, carbon nanotube based and carbon-filled nanopipettes, and tunneling nanoelectrodes...
October 7, 2016: Analyst
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