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Yeny Perdomo, Verónica Arancibia, Olimpo García-Beltrán, Edgar Nagles
A fast, sensitive, and selective method for the simultaneous determination of one pair of synthetic colorants commonly found mixed in food products, Amaranth (AM) and Tartrazine (TZ), based on their adsorption and oxidation on a screen-printed electrode (SPE) is presented. The variation of peak current with pH, supporting electrolyte, adsorption time, and adsorption potential were optimized using square wave adsorptive voltammetry. The optimal conditions were found to be: pH 3.2 (PBS), Eads 0.00 V, and tads 30 s...
November 18, 2017: Sensors
Majid Arvand, Mona Sanayeei, Shiva Hemmati
In this study, we aim to design a simple and effective electrochemical DNA biosensor based on a carbon paste electrode modified with ds-DNA/poly(L-cysteine)/Fe3O4 nanoparticles-graphene oxide (ds-DNA/p(L-Cys)/Fe3O4 NPs-GO/CPE) for sensitive detection of adenine (A) and guanine (G). The electrocatalytic oxidation of A and G on the electrode was explored by differential pulse voltammetry (DPV) and cyclic voltammetry (CV). This sensor shows separated and well-defined peaks for A and G, by which one can determine these biological bases individually or simultaneously...
November 7, 2017: Biosensors & Bioelectronics
Ying Chen, Yu Li, Dongmei Deng, Haibo He, Xiaoxia Yan, Zhenxin Wang, Chunhai Fan, Liqiang Luo
A novel and sensitive sandwich immunosensor for amperometric determination of carcinoembryonic antigen (CEA) was designed using Au nanoparticles-titanium dioxide-graphene (AuNPs-TiO2-graphene) nanocomposites. Dopamine-functionalized graphene was firstly prepared by π-stacking interaction, and TiO2 was then attached to the surface of dopamine-graphene by the specificity and high affinity of enediol ligands to Ti (IV). Afterwards, AuNPs-TiO2-graphene nanocomposites were synthesized with photo-reduction approach under ultraviolet irradiation...
November 17, 2017: Biosensors & Bioelectronics
Dong Liu, Pengcheng Du, Wenli Wei, Hongxing Wang, Qi Wang, Peng Liu
Polyaniline coated reduced graphene oxide/carbon nanotube composite fibers ((RGO/CNTs)@PANI, RCP) with skeleton/skin structure are designed as fiber-shaped electrodes for high performance all-solid-state symmetric supercapacitor. The one-dimensional reduced graphene oxide/carbon nanotube composite fibers (RGO/CNTs, RC) are prepared via a simple in-situ reduction of graphene oxide in presence of carbon nanotubes in quartz glass pipes, which exhibit excellent mechanical performance of >193.4 MPa of tensile strength...
November 10, 2017: Journal of Colloid and Interface Science
Maximilian Dürr, Johannes Klein, Axel Kahnt, Sabine Becker, Ralph Puchta, Biprajit Sarkar, Ivana Ivanović-Burmazović
A dinuclear ruthenium complex bridged by 2,3,5,6-pyrazinetetracarboxylic acid (μ-LH2(2-)) was synthesized and characterized by X-ray crystallography, cyclic voltammetry under ambient and elevated pressures, electron paramagnetic resonance (EPR) and UV/vis-NIR (NIR = near-infrared) spectroelectrochemistry, pulse radiolysis, and computational methods. We probed for the first time in the field of mixed-valency the use of high-pressure electrochemical methods. The investigations were directed toward the influence of the protonation state of the bridging ligand on the electronic communication between the ruthenium ions, since such behavior is interesting in terms of modulating redox chemistry by pH...
November 20, 2017: Inorganic Chemistry
Ingo Krossing, Miriam Mareen Schwab, Daniel Himmel, Sylwia Kacprzak, Valentin Radtke, Daniel Kratzert, Philippe Weis, Melanie Wernet, Andreas Peter, Zeinab Yassine, Dominik Schmitz, Ernst-Wilhelm Scheidt, Wolfgang Scherer, Stefan Weber, Wolfram Feuerstein, Frank Breher, Alexander Higelin
The recently published purely metalorganic NiI salt [Ni(cod)2][Al(ORF)4] (1, cod = 1,5-cyclooctadiene, RF = C(CF3)3) provides a starting point for a new synthesis strategy leading to NiI phosphine complexes, replacing cod ligands by phosphines. Clearly visible colour changes indicate reactions within minutes, while quantum chemical calculations (PBE0-D3(BJ)/def2-TZVPP) approve exergonic reaction enthalpies in all performed ligand exchange reactions. Hence, [Ni(dppp)2][Al(ORF)4] (2, dppp = 1,3-Bis(diphenylphosphino)propane), [Ni(dppe)2][Al(ORF)4] (3, dppe = 1,3-Bis(diphenyl-phosphino)ethane), three-coordinate [Ni(PPh3)3][Al(ORF)4] (4) and a remarkable two-coordinate NiI phosphine complex [Ni(PtBu3)2][Al(ORF)4] (5) were characterised via single crystal X-ray structure analysis...
November 20, 2017: Chemistry: a European Journal
P Adwin Jose, J Dhaveethu Raja, M Sankarganesh, J Rajesh
In this work, we have synthesized pyrimidine derivatives of Schiff base ligand 2-(4,6-dimethoxypyrimidin-2-ylimino)methyl)-6-methoxyphenol (DPMM) stabilized copper nanoparticles (DPMM-CuNPs) and nickel nanoparticles (DPMM-NiNPs) by modified Brust-Schiffrin technique as two step phase transfer assisted method and confirmed by UV-Visible, SEM and TEM analysis. The free radical scavenging activity of DPMM, DPMM-CuNPs &DPMM-NiNPs with 2, 2'-diphenylpicryl hydrazyl (DPPH), hydrogen peroxide (H2O2) super oxide dismutase (SOD) and nitric oxide (NO) shows that the antioxidant activity of DPMM-CuNPs is higher than DPMM &DPMM-NiNPs...
November 6, 2017: Journal of Photochemistry and Photobiology. B, Biology
Paula P Campos, Leonardo Fernandes Fraceto, Marystela Ferreira
Dermal drug release systems are an important area of research because they can be applied to the skin in a non-invasive procedure using a lower concentration of drugs. In this study, we have developed two types of Layer-by-Layer (LbL) films for releasing emodin (EM). In one system, EM was intercalated with poly(ethylenimine) PEI and poly(vinyl sufonate) (PVS) polyelectrolytes, forming (PEI/PVS)2(PEI/EM)7; in another, EM was incorporated in liposomes obtained by mixing dipalmitoyl phosphatidyl glycerol (DPPG) and palmitoyl oleoyl phosphatidyl glycerol (POPG) lipids, forming (PEI/PVS)2(PEI/DPPG-POPG-EM)7...
November 12, 2017: Colloids and Surfaces. B, Biointerfaces
Brain Barry, Graeme Soper, Juha Hurmalainen, Akseli Mansikkamäki, Katherine N Robertson, William L McClennan, Alex J Veinot, Tracey L Roemmele, Ulrike Werner-Zwanziger, René T Boeré, Heikki M Tuononen, Jason Clyburne, Jason Masuda
An extended π-system containing two [3]cumulene fragments separated by a p-carbo-quinoid and stabilized by two capping N-heterocyclic carbenes (NHCs) has been prepared. Mono- and bis-imidazolidinium ethynyl cations have also been synthesized from the reaction of an NHC with phenylethynyl bromide or 1,4-bis(bromoethynyl)benzene. Cyclic voltammetry coupled with synthetic and structural studies showed that the dication is readily reduced to a neutral, singlet bis-1,4-([3]cumulene)-p-carbo-quinoid due to the π-accepting properties of the capping NHCs...
November 19, 2017: Angewandte Chemie
Tawatchai Kangkamano, Apon Numnuam, Warakorn Limbut, Proespichaya Kanatharana, Tirayut Vilaivan, Panote Thavarungkul
A label-free electrochemical miRNA biosensor was developed based on a pyrrolidinyl peptide nucleic acid (acpcPNA)/polypyrrole (PPy)/silver nanofoam (AgNF) modified electrode. The AgNF was electrodeposited as redox indicator on a gold electrode, which was then functionalized with an electropolymerized layer of PPy, a conducting polymer, to immobilize the PNA probes. The fabrication process was investigated by electrochemical impedance spectroscopy. The biosensor was used to detect miRNA-21, a biomarker abnormally expressed in most cancers...
November 6, 2017: Biosensors & Bioelectronics
Lingtao Zhu, Xiaodan Wang, Yunxiu Han, Yingming Cai, Jiahui Jin, Hongmei Wang, Liping Xu, Ruijia Wu
An electrochemical sensor for detection of beef taste was designed in this study. This sensor was based on the structure of polyvinyl chloride/polypyrrole (PVC/PPy), which was polymerized onto the surface of a platinum (Pt) electrode to form a Pt-PPy-PVC film. Detecting by electrochemical methods, the sensor was well characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The sensor was applied to detect 10 rib-eye beef samples and the accuracy of the new sensor was validated by sensory evaluation and ion sensor detection...
November 4, 2017: Meat Science
Francesco Crespi
Somatostatin (SRIF) is widely distributed throughout the body, and regulates the endocrine system via interactions with various hormones, including the pituitary growth hormone, the thyroid stimulating hormone and the majority of the hormones of the gastrointestinal tract. SRIF is present in the central nervous system (CNS), where it affects rates of neurotransmission, and is also reported to be active in the intestinal tract, with evidence that stressed rats present a significant decrease in antral somatostatin-like immunoreactivity (SLI)...
November 17, 2017: Biosensors
Saptarshi Biswas, Shuwen Ma, Stefano Nuzzo, Brendan Twamley, Andrew T Russell, James A Platts, František Hartl, Robert J Baker
A series of complexes [Et4N][Ln(NCS)4(H2O)4] (Ln = Pr, Tb, Dy, Ho, Yb) have been structurally characterized, all showing the same structure, namely a distorted square antiprismatic coordination geometry, and the Ln-O and Ln-N bond lengths following the expected lanthanide contraction. When the counterion is Cs(+), a different structural motif is observed and the eight-coordinate complex Cs5[Nd(NCS)8] isolated. The thorium compounds [Me4N]4[Th(NCS)7(NO3)] and [Me4N]4[Th(NCS)6(NO3)2] have been characterized, and high coordination numbers are also observed...
November 16, 2017: Inorganic Chemistry
K Michael Schäfer, Leonie Reinders, Jan Fiedler, Mark R Ringenberg
Recently we had reported the noninnocent behavior of 1,1'-bis(diphenylphosphino)ferrocene (dppf) in Fe(CO)3dppf [Ringenberg et al., Inorg. Chem., 2017, 56, 7501]. Moving to the left in the periodic table, HMn(CO)3(dRpf) where dRpf = dppf (1H) and 1,1'-bis(diisopropylphosphino)ferrocene (dippf) (2H) were synthesized. The hydride ligand was removed by protonation with [(Et2O)2H][B(Ar(F))4] ([B(Ar(F))4](-) = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate), resulting in the rapid evolution of H2 followed by the formation of an Fe→Mn interaction...
November 16, 2017: Inorganic Chemistry
Hamid R Lotfi Zadeh Zhad, Rebecca Y Lai
We report for the first time the use of hexavalent chromium (Cr(VI)) as an electrocatalyst in electrochemical DNA sensing. For both stem-loop probe and linear probe electrochemical DNA sensors, the increase in probe rigidity upon target hybridization alters the accessibility of Cr(VI) to the methylene blue label on the surface-immobilized DNA probes. This change results in an enhancement in the electrocatalytic current when the sensors are interrogated using cyclic voltammetry at a slow scan rate. The incorporation of this electrocatalyst does not affect the normal "signal-off" sensing behavior observed in alternating current voltammetry; instead it enables simultaneous "signal-on" and "signal-off" detection of the target, while maintaining noted attributes of this class of folding- and dynamics-based sensors such as reusability and high selectivity...
November 16, 2017: Analytical Chemistry
Nicholas Pearce, E Stephen Davies, Raphael Horvath, Constance R Pfeiffer, Xue-Zhong Sun, William Lewis, Jonathan McMaster, Michael W George, Neil R Champness
Varying the degree of thionation of a series of naphthalene diimide (NDI) and naphthalic imide (NI) phenothiazine dyad systems affords a systematic approach for tuning the system's donor-acceptor energy gap. Each dyad was compared to model NDI/NI systems and fully characterised through single crystal X-ray diffraction, NMR, cyclic voltammetry, electron paramagnetic resonance (EPR), transient absorption spectroscopy (TA), time-resolved infra-red spectroscopy (TRIR) and DFT. The measurements reveal that thionation increases both electron affinity of the NDI/NI acceptor dyad component and accessibility of the singly or doubly reduced states...
November 15, 2017: Physical Chemistry Chemical Physics: PCCP
O V Soldatkina, I S Kucherenko, V M Pyeshkova, S A Alekseev, O O Soldatkin, S V Dzyadevych
In this work, we studied the conditions of deposition of a semipermeable polyphenylenediamine (PPD)-based membrane on amperometric disk platinum electrodes. Restricting an access of interfering substances to the electrode surface, the membrane prevents their impact on the sensor operation. Two methods of membrane deposition by electropolymerization were compared-at varying potential (cyclic voltammetry) and at constant potential. The cyclic voltammetry was shown to be easier in performing and providing better properties of the membrane...
November 14, 2017: Nanoscale Research Letters
S Selvarajan, A Suganthi, M Rajarajan
Herein, we report a one-pot synthesis of structurally uniform and electrochemically active graphitic carbon nitride/nickel oxide (g-C3N4/NiO) nanocomposite and an investigation on the electrocatalytic oxidation of quercetin (QR). The synthesized g-C3N4/NiO nanocomposite has uniform surface distribution, which was characterized with scanning electron microscopy (SEM). Moreover, the composition of synthesized g-C3N4/NiO nanocomposite was characterized by UV-vis-spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR spectra), BET, SEM and HRTEM...
March 2018: Ultrasonics Sonochemistry
Mohammad Ali Khayamian, Majid Baniassadi, Mohammad Abdolahad
Sonoporation is applied to enhance the permeability of the cell to bioactive materials by employing the acoustic cavitation of microbubbles. This phenomena would be helpful in molecular biology, delivery of large molecules into the cells and gene therapy. Many methods have been applied to monitor the biological effects and trace of sonoporation on the cells such as scanning/transmission electron microscopy, confocal imaging and flow cytometry. Here, we monitored the effect of sonoporation on the cells using electrochemical method with an integrated three electrode system...
March 2018: Ultrasonics Sonochemistry
Balasubramaniam Gnana Sundara Raj, Senniyappan Bhuvaneshwari, Jerry J Wu, Abdullah M Asiri, Sambandam Anandan
In this work, a simple sonochemical route was followed to synthesize cobalt stannate (Co2SnO4) nanocubes using stannous and cobalt chlorides as the precursors in alkaline medium at room temperature. The structure, composition and surface morphology of synthesized Co2SnO4 nanocubes have been characterized by using X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) indicates that the Co2SnO4 nanocubes are crystalline, single-phase without any impurity phase; the sizes of nanocubes are ∼100 nm...
March 2018: Ultrasonics Sonochemistry
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