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https://www.readbyqxmd.com/read/28101950/molecular-binding-of-toxic-phenothiazinium-derivatives-azures-to-bovine-serum-albumin-a-comparative-spectroscopic-calorimetric-and-in-silico-study
#1
Somnath Das, Md Maidul Islam, Gopal Chandra Jana, Anirudha Patra, Pradeep K Jha, Maidul Hossain
In this paper, the comparative binding behavior of antimalarial drug azure A, azure B and azure C with bovine serum albumin (BSA) has been studied. The interaction has been confirmed by multispectroscopic (UV, fluorescence, Fourier transform infrared (FT-IR), and circular dichroism) and molecular docking techniques. The experimental results show that azure B has the highest BSA binding affinity followed by azure A and azure C. The experimental evidence of binding showed a static quenching mechanism in the interaction azures with BSA...
January 19, 2017: Journal of Molecular Recognition: JMR
https://www.readbyqxmd.com/read/28101708/characterization-of-interaction-between-amino-acids-and-fulvic-like-organic-matter-by-fluorescence-spectroscopy-combining-thermodynamic-calculation
#2
Tao Lin, Bingwei Hou, Jian Wang, Yaqun Xu, Wei Chen
Dissolved organic matter (DOM), as a very fine colloidal suspension, could inevitably affect the transformation process of dissolved organic nitrogen (DON) in drinking water treatment. Tryptophan and tyrosine were used as representatives of DON to investigate the interactions between amino acids and fulvic-like components of fluorescent DOM using titration experiments. The fluorescence intensity decreased significantly with the increasing fulvic acid (FA) concentration, suggesting that FA could greatly quench the intrinsic fluorescence of amino acids such as tryptophan and tyrosine...
January 18, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28101183/protective-effect-of-berberine-against-oxidative-stress-induced-apoptosis-in-rat-bone-marrow-derived-mesenchymal-stem-cells
#3
Wangyang Li, Yamei Liu, Bin Wang, Yiwen Luo, Nianhong Hu, Dongfeng Chen, Xunchao Zhang, Yunpu Xiong
Bone marrow-derived mesenchymal stem cells (BMSCs) have the potential to be used for the treatment of delayed union, nonunion or persistent bone defects in MSC-based cell therapy. However, implantation of BMSCs into the fracture site is confronted with apoptosis on account of harsh conditions and oxidative stress. In the present study, the anti-apoptotic effects of berberine (BBR) on BMSCs subjected to hydrogen peroxide (H2O2) are investigated, and the potential underlying mechanisms are explored. Oxidative injury was induced by exposure to H2O2, and cell viability was assessed using a cell counting kit-8 assay...
December 2016: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/28099813/photoactive-donor-acceptor-composite-nanoparticles-dispersed-in-water
#4
Laurie Parrenin, Gildas Laurans, Eleni Pavlopoulou, Guillaume Fleury, Gilles Pecastaings, Cyril Brochon, Laurence Vignau, Georges Hadziioannou, Eric Cloutet
A major issue that inhibits large-scale fabrication of organic solar modules is the use of chlorinated solvents considered as toxic and hazardous. In this work, composite particles of poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2',1',3'-benzothiadiazole] (PCDTBT) and [6,6]-Phenyl C71 butyric acid methyl ester (PC71BM) were obtained in water from a versatile and a ready-to-market methodology based on miniemulsion post-polymerization. Depending on experimental conditions, size-controlled particles comprising both the electron-donor and the electron-acceptor were obtained and characterized using transmission electron microscopy (TEM), atomic force microscopic (AFM), small-angle neutron scattering (SANS), UV-visible absorption and fluorescence spectroscopies...
January 18, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28099157/high-quality-epitaxial-graphene-by-hydrogen-etching-of-3c-sic-111-thin-film-on-si-111
#5
Bharati Gupta, Carlo Mariani, Josh Lipton-Duffin, Nunzio Motta, Pierluigi Mondelli, Maria Betti
Etching with atomic hydrogen as a preparation step before the high-temperature growth process of graphene onto a thin 3C-SiC film grown on Si(111) greatly improves the structural quality of topmost graphene layers. Pit formation and island coalescence, which are typical of graphene growth by SiC graphitization, are quenched and accompanied by widening of the graphene domain sizes to hundreds of nm, and by a significant reduction in surface roughness down to a single substrate bilayer. The surface reconstructions expected for graphene and the underlying layer are shown with atomic resolution by scanning tunnelling microscopy (STM)...
January 18, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28099016/influence-of-energetic-disorder-on-exciton-lifetime-and-photoluminescence-efficiency-in-conjugated-polymers
#6
Irina Rörich, Oleksandr V Mikhnenko, Dominik W Gehrig, Paul W M Blom, Nicoleta Irina Craciun
Using time-resolved photoluminescence (TRPL) spectroscopy the exciton lifetime in a range of conjugated polymers is investigated. For poly(p-phenylene vinylene) (PPV)-based derivatives and a polyspirobifluorene copolymer (PSBF) we find that the exciton lifetime is correlated with the energetic disorder. Better ordered polymers exhibit a single exponential PL decay with exciton lifetimes of a few hundred picoseconds, whereas polymers with a larger degree of disorder show multi-exponential PL decays with exciton lifetimes in the nanosecond regime...
January 18, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28098970/strong-enhancement-of-photoelectric-conversion-efficiency-of-co-hybridized-polymer-solar-cell-by-silver-nanoplates-and-core-shell-nanoparticles
#7
Wenfei Shen, Jianguo Tang, Yao Wang, Jixian Liu, Linjun Huang, Weichao Chen, Lanlan Yang, Wei Wang, Yanxin Wang, Renqiang Yang, Jungheum Yun, Laurence A Belfiore
A new way was meticulously designed to utilize the localized surface plasmon resonance (LSPR) effect and the light scattering effect of silver nanoplate (Ag-nPl) and core-shell Ag@SiO2 nanoparticles (Ag@SiO2-NPs) to enhance the photovoltaic performances of polymer solar cells (PSCs). To prevent direct contact between silver nanoparticles (Ag-NPs) and photo-active materials which will cause electrons quenching, bare Ag-nPl were spin-coated on indium tin oxide and silica capsulated Ag-NPs were incorporated to PBDTTT-C-T:PC71BM active layer...
January 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28098833/role-of-electron-driven-proton-transfer-processes-in-the-ultrafast-deactivation-of-photoexcited-anionic-8-oxoguanine-adenine-and-8-oxoguanine-cytosine-base-pairs
#8
Xiuxiu Wu, Tolga N V Karsili, Wolfgang Domcke
It has been reported that 8-oxo-7,8-dihydro-guanosine (8-oxo-G), which is the main product of oxidative damage of DNA, can repair cyclobutane pyrimidine dimer (CPD) lesions when incorporated into DNA or RNA strands in proximity to such lesions. It has therefore been suggested that the 8-oxo-G nucleoside may have been a primordial precursor of present-day flavins in DNA or RNA repair. Because the electron transfer leading to the splitting of a thymine-thymine pair in a CPD lesion occurs in the photoexcited state, a reasonably long excited-state lifetime of 8-oxo-G is required...
January 14, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28098798/free-radical-scavenging-activity-of-drops-and-spray-containing-propolis-an-epr-examination
#9
Pawel Olczyk, Katarzyna Komosinska-Vassev, Pawel Ramos, Lukasz Mencner, Krystyna Olczyk, Barbara Pilawa
The influence of heating at a temperature of 50 °C and UV-irradiation of propolis drops and spray on their free radical scavenging activity was determined. The kinetics of interactions of the propolis samples with DPPH free radicals was analyzed. Interactions of propolis drops and propolis spray with free radicals were examined by electron paramagnetic resonance spectroscopy. A spectrometer generating microwaves of 9.3 GHz frequency was used. The EPR spectra of the model DPPH free radicals were compared with the EPR spectra of DPPH in contact with the tested propolis samples...
January 13, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28098350/endogenous-circadian-rhythms-in-pigment-composition-induce-changes-in-photochemical-efficiency-in-plant-canopies
#10
José Ignacio García-Plazaola, Beatriz Fernández-Marín, Juan Pedro Ferrio, Josu G Alday, Günter Hoch, Damien Landais, Alexandru Milcu, David T Tissue, Jordi Voltas, Arthur Gessler, Jacques Roy, Víctor Resco de Dios
There is increasing evidence that the circadian clock is a significant driver of photosynthesis that becomes apparent when environmental cues are experimentally held constant. We studied whether the composition of photosynthetic pigments is under circadian regulation, and whether pigment oscillations lead to rhythmic changes in photochemical efficiency. To address these questions, canopies of bean and cotton were maintained, after an entrainment phase, under constant (light or darkness) conditions for 30-48 h...
January 18, 2017: Plant, Cell & Environment
https://www.readbyqxmd.com/read/28098332/revisiting-the-optimized-doping-ratio-in-core-shell-nanostructured-upconversion-particles
#11
Bin Shen, Shengming Cheng, Yuyang Gu, Danrui Ni, Yilin Gao, Qianqian Su, Wei Feng, Fuyou Li
The development of rare-earth doped upconversion nanoparticles (RE-UCNPs) in various applications is fuelling the demand for nanoparticles with highly enhanced upconversion luminescence (UCL). Although the core/shell structure is proved to enhance the UCL effectively, there is still plenty of room to further improve the UCL by optimizing the doping ratio of the materials. In this article, a general strategy is demonstrated to achieve highly-enhanced visible UCL in core/shell nanostructured NaREF4 by increasing the doping ratio of Yb(3+) in the core region...
January 18, 2017: Nanoscale
https://www.readbyqxmd.com/read/28098322/flory-theory-of-randomly-branched-polymers
#12
Ralf Everaers, Alexander Y Grosberg, Michael Rubinstein, Angelo Rosa
Randomly branched polymer chains (or trees) are a classical subject of polymer physics with connections to the theory of magnetic systems, percolation and critical phenomena. More recently, the model has been reconsidered for RNA, supercoiled DNA and the crumpling of topologically-constrained polymers. While solvable in the ideal case, little is known exactly about randomly branched polymers with volume interactions. Flory theory provides a simple, unifying description for a wide range of branched systems, including isolated trees in good and θ-solvent, and tree melts...
January 18, 2017: Soft Matter
https://www.readbyqxmd.com/read/28098308/a-core-multiple-shell-nanostructure-enabling-concurrent-upconversion-and-quantum-cutting-for-photon-management
#13
Wei Shao, Guanying Chen, Tymish Y Ohulchanskyy, Chunhui Yang, Hans Ågren, Paras N Prasad
Photon management enables the manipulation of the number of input photons by conversion of two or more light quanta into one (upconversion) or vice versa (quantum cutting). Simultaneous realization of both these processes in a single unit provides unique opportunities of efficient utilization of photons throughout a broad spectral range. Yet, concurrent realization of these two parallel optical processes in one single unit remains elusive, limiting its impact on many existing or possible future applications such as for panchromatic photovoltaics...
January 18, 2017: Nanoscale
https://www.readbyqxmd.com/read/28097712/force-generation-by-titin-folding
#14
Zsolt Mártonfalvi, Pasquale Bianco, Katalin Naftz, György G Ferenczy, Miklós Kellermayer
Titin is a giant protein that provides elasticity to muscle. As the sarcomere is stretched, titin extends hierarchically according to the mechanics of its segments. Whether titin's globular domains unfold during this process and how such unfolded domains might contribute to muscle contractility are strongly debated. To explore the force-dependent folding mechanisms, here we manipulated skeletal-muscle titin molecules with high-resolution optical tweezers. In force-clamp mode, after quenching the force (<10 pN), extension fluctuated without resolvable discrete events...
January 18, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/28097462/thermally-stable-schiff-base-and-its-metal-complexes-molecular-docking-and-protein-binding-studies
#15
Umran Duru Kamaci, Musa Kamaci, Aysegul Peksel
In this paper, interaction of Schiff base and its metal complexes carrying naphthalene ring in the structure with bovine serum albumin (BSA) were investigated using UV-vis absorption, fluorescence spectroscopies and molecular docking methods. The effect on the binding mechanism and properties of these compounds containing metal-free, iron and copper ions were also investigated. The fluorescence spectroscopy results showed that fluorescence intensity of BSA in the presence of different concentration of ligands was decreased through a static quenching mechanism...
January 18, 2017: Journal of Fluorescence
https://www.readbyqxmd.com/read/28095360/enzyme-catalyzed-michael-addition-for-the-synthesis-of-warfarin-and-its-determination-via-fluorescence-quenching-of-l-tryptophan
#16
Yusheng Yuan, Liu Yang, Shaopu Liu, Jidong Yang, Hui Zhang, Jingjing Yan, Xiaoli Hu
A sensitive fluorescence sensor for warfarin was proposed via quenching the fluorescence of l-tryptophan due to the interaction between warfarin and l-tryptophan. Warfarin, as one of the most effective anticoagulants, was designed and synthesized via lipase from porcine pancreas (PPL) as a biocatalyst to catalyze the Michael addition of 4-hydroxycoumarin to α, β-unsaturated enones in organic medium in the presence of water. Furthermore, the spectrofluorometry was used to detect the concentration of warfarin with a linear range and detection limit (3σ/k) of 0...
January 9, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28094995/photoluminescence-probing-of-complex-h2o-adsorption-on-ingan-gan-nanowires
#17
Konrad Maier, Andreas Helwig, Gerhard Muller, Pascal Hille, Jörg Teubert, Martin Eickhoff
We demonstrate that the complex adsorption behavior of H2O on InGaN/GaN nanowire arrays is directly revealed by their ambient-dependent photoluminescence properties. Under low-humidity, ambient-temperature, and low-excitation-light conditions, H2O adsorbates cause a quenching of the photoluminescence. In contrast, for high humidity levels, elevated temperature, and high excitation intensity, H2O adsorbates act as efficient photoluminescence enhancers. We show that this behavior, which can only be detected due to the low operation temperature of the InGaN/GaN nanowires, can be explained on the basis of single H2O adsorbates forming surface recombination centers and multiple H2O adsorbates forming surface passivation layers...
January 17, 2017: Nano Letters
https://www.readbyqxmd.com/read/28094932/series-d-f-heteronuclear-metal-organic-frameworks-color-tunability-and-luminescent-probe-with-switchable-properties
#18
Xun Feng, Yuquan Feng, Nan Guo, Yiling Sun, Tian Zhang, Lufang Ma, Liya Wang
A series of five unique d-f heteronuclear luminescent metal-organic frameworks (MOFs) in an entangled polyrotaxane array and the light-harvesting block homonuclear zinc compound have been isolated successfully and characterized. The series of isostructural polymers feature 3,4-connected (4.8(2))(4.8(3).9(2))(6.8.9)2(6.9(2))(8(3)) topology and high stability, exhibiting diverse void spaces. By taking advantage of the isostructural MOFs 2 and 3, the intensities of red and green emissions can be modulated by adjusting the ratios of Eu(III) and Tb(III) ions correspondingly, and white-light emission can be generated by a combination of different doped Tb(III) and Eu(III) concentrations...
January 17, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28094527/binding-and-inhibitory-effect-of-dyes-amaranth-and-tartrazine-on-amyloid-fibrillation-in-lysozyme
#19
Anirban Basu, Gopinatha Suresh Kumar
Interaction of two food colorant dyes, amaranth and tartrazine, with lysozyme was studied employing multiple biophysical techniques. The dyes exhibited hypochromic changes in the presence of lysozyme. The intrinsic fluorescence of lysozyme was quenched by both dyes; amaranth was a more efficient quencher than tartrazine. The equilibrium constant of amaranth was higher than that of tartarzine. From FRET analysis, the binding distances for amaranth and tartrazine were calculated to be 4.51 and 3.93 nms, respectively...
January 17, 2017: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/28094379/luminescent-aryl-group-eleven-metal-complexes
#20
José M López-de-Luzuriaga, Miguel Monge, M Elena Olmos
Among the coinage metal complexes displaying luminescent properties, those bearing C-donor aryl ligands have an increasing part in the chemistry of these metals. These types of ligands confer a high kinetic and thermodynamic stability on the complexes, but they can also be involved in the photoluminescent behaviour of the complexes. The development of new aryl-containing complexes of group eleven metals, the study of their photoluminescent properties and their related properties and applications are discussed in this perspective...
January 17, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
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