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https://www.readbyqxmd.com/read/28433937/perturbation-effect-of-reduced-graphene-oxide-quantum-dots-rgoqds-on-aryl-hydrocarbon-receptor-ahr-pathway-in-zebrafish
#1
Jing-Hui Zhang, Tai Sun, Aping Niu, Yu-Mei Tang, Shun Deng, Wei Luo, Qun Xu, Dapeng Wei, De-Sheng Pei
Graphene quantum dots (GQDs) has been widely used in enormous fields, however, the inherent molecular mechanism of GQDs for potential risks in biological system is still elusive to date. In this study, the outstanding reduced graphene quantum dots (rGOQDs) with the QY as high as 24.62% were successfully synthesized by the improved Hummers method and DMF hydrothermal treatment approach. The rGOQDs were N-doped photoluminescent nanomaterials with functional groups on the surface. The fluorescent bio-imaging was performed by exposing zebrafish in different concentrations of the as-prepared rGOQDs, and the distribution of rGOQDs was successfully observed...
April 15, 2017: Biomaterials
https://www.readbyqxmd.com/read/28432940/a-sandwich-immunoassay-for-brucellosis-diagnosis-based-on-immune-magnetic-beads-and-quantum-dots
#2
Li Li, Dehui Yin, Kun Xu, Yushen Liu, Dandan Song, Juan Wang, Chao Zhao, Xiuling Song, Juan Li
Brucellosis is a serious zoonosis with a rapid increase in incidence across epidemic regions. Currently, there are numerous methods for diagnosing brucellosis. However, these studies often have a few defects, such as low sensitivity, poor specificity, time consuming, laborious, and even potential biological risk. To overcome these shortcomings, we have developed a rapid, sensitive and accurate diagnosis procedure for brucellosis based on the immune magnetic beads (IMB) probe and quantum dots (QDs) - staphylococcal protein A (SPA) probe...
April 6, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/28432315/experimental-evidence-of-fano-resonances-in-nanomechanical-resonators
#3
Stefano Stassi, Alessandro Chiadò, Giuseppe Calafiore, Gianluca Palmara, Stefano Cabrini, Carlo Ricciardi
Fano resonance refers to an interference between localized and continuum states that was firstly reported for atomic physics and solid-state quantum devices. In recent years, Fano interference gained more and more attention for its importance in metamaterials, nanoscale photonic devices, plasmonic nanoclusters and surface-enhanced Raman scattering (SERS). Despite such interest in nano-optics, no experimental evidence of Fano interference was reported up to now for purely nanomechanical resonators, even if classical mechanical analogies were referred from a theoretical point of view...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28431312/melatonin-charge-transfer-complex-with-2-3-dichloro-5-6-dicyano-1-4-benzoquinone-molecular-structure-dft-studies-thermal-analyses-evaluation-of-biological-activity-and-utility-for-determination-of-melatonin-in-pure-and-dosage-forms
#4
Gehad G Mohamed, Maher M Hamed, Nadia G Zaki, Mohamed M Abdou, Marwa El-Badry Mohamed, Abanoub Mosaad Abdallah
A simple, accurate and fast spectrophotometric method for the quantitative determination of melatonin (ML) drug in its pure and pharmaceutical forms was developed based on the formation of its charge transfer complex with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an electron acceptor. The different conditions for this method were optimized accurately. The Lambert-Beer's law was found to be valid over the concentration range of 4-100μgmL(-1) ML. The solid form of the CT complex was structurally characterized by means of different spectral methods...
April 4, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28427899/energy-and-information-flows-in-biological-systems-bioenergy-transduction-of-v1-atpase-rotary-motor-and-dynamics-of-thermodynamic-entropy-in-information-flows
#5
REVIEW
Ichiro Yamato, Takeshi Murata, Andrei Khrennikov
We classify research fields in biology with respect to flows of materials, energy, and information. We investigate energy transducing mechanisms in biology, using as a representative the typical molecular rotary motor V1-ATPase from a bacterium Enterococcus hirae. The structures of several intermediates of the rotary motor are described and the molecular mechanism of the motor converting chemical energy into mechanical energy is discussed. Comments and considerations on the information flows in biology, especially on the thermodynamic entropy in quantum physical and biological systems, are presented in section 3 in a biologist friendly manner...
April 17, 2017: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/28421739/an-ultra-efficient-cap-exchange-protocol-to-compact-biofunctional-quantum-dots-for-sensitive-ratiometric-biosensing-and-cell-imaging
#6
Weili Wang, Yuan Guo, Christian Tiede, Siyuan Chen, Michal Kopytynski, Yifei Kong, Alexander N Kulak, Darren Tomlinson, Rongjun Chen, Michael John McPherson, Dejian Zhou
An ultra-efficient cap-exchange protocol (UCEP) that can convert hydrophobic quantum dots (QDs) into stable, biocompatible and aggregation-free water-dispersed ones at a ligand:QD molar ratio (LQMR) as low as 500, some 20-200 fold less than most literature methods has been developed. The UCEP works conveniently with air-stable lipoic acid (LA)-based ligands by exploiting tris(2-carboxylethyl phosphine) based rapid in situ reduction. The resulting QDs are compact (hydrodynamic radius, Rh, <4.5 nm), bright (retaining >90% of original fluorescence), resist nonspecific adsorption of proteins and display good stability in biological buffers even with high salt content (e...
April 19, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28420869/verification-of-oligomycin-a-structure-synthesis-and-biological-evaluation-of-33-dehydrooligomycin-a
#7
Lyudmila N Lysenkova, Oleg Y Saveljev, Natalya E Grammatikova, Vladimir B Tsvetkov, Olga B Bekker, Valery N Danilenko, Lyubov G Dezhenkova, Eugene E Bykov, Olga A Omelchuk, Alexander M Korolev, Andrey E Shchekotikhin
Although, the structure of oligomycin A (1) was confirmed by spectroscopic and chemical evaluations, some crystallographic data cast doubt on the originally adopted structure of the side 2-hydroxypropyl moiety of this antibiotic. It was suggested that the side chain of the oligomycin is enol-related (2-hydroxy-1-propenyl). To clarify this matter we synthesized and evaluated 33-dehydrooligomycin A (2) prepared by the Kornblum oxidation of 33-O-mesyloligomycin A (3) by dimethyl sulfoxide. NMR data for 33-dehydrooligomycin (2) and results of quantum chemical calculations have shown that this derivative exists in the keto rather than in the enol tautomer 2a...
April 19, 2017: Journal of Antibiotics
https://www.readbyqxmd.com/read/28420789/structural-and-stereoelectronic-insights-into-oxygenase-catalyzed-formation-of-ethylene-from-2-oxoglutarate
#8
Zhihong Zhang, Tristan J Smart, Hwanho Choi, Florence Hardy, Christopher T Lohans, Martine I Abboud, Melodie S W Richardson, Robert S Paton, Michael A McDonough, Christopher J Schofield
Ethylene is important in industry and biological signaling. In plants, ethylene is produced by oxidation of 1-aminocyclopropane-1-carboxylic acid, as catalyzed by 1-aminocyclopropane-1-carboxylic acid oxidase. Bacteria catalyze ethylene production, but via the four-electron oxidation of 2-oxoglutarate to give ethylene in an arginine-dependent reaction. Crystallographic and biochemical studies on the Pseudomonas syringae ethylene-forming enzyme reveal a branched mechanism. In one branch, an apparently typical 2-oxoglutarate oxygenase reaction to give succinate, carbon dioxide, and sometimes pyrroline-5-carboxylate occurs...
April 18, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28420346/linoleic-acid-is-this-the-key-that-unlocks-the-quantum-brain-insights-linking-broken-symmetries-in-molecular-biology-mood-disorders-and-personalistic-emergentism
#9
REVIEW
Massimo Cocchi, Chiara Minuto, Lucio Tonello, Fabio Gabrielli, Gustav Bernroider, Jack A Tuszynski, Francesco Cappello, Mark Rasenick
In this paper we present a mechanistic model that integrates subneuronal structures, namely ion channels, membrane fatty acids, lipid rafts, G proteins and the cytoskeleton in a dynamic system that is finely tuned in a healthy brain. We also argue that subtle changes in the composition of the membrane's fatty acids may lead to down-stream effects causing dysregulation of the membrane, cytoskeleton and their interface. Such exquisite sensitivity to minor changes is known to occur in physical systems undergoing phase transitions, the simplest and most studied of them is the so-called Ising model, which exhibits a phase transition at a finite temperature between an ordered and disordered state in 2- or 3-dimensional space...
April 19, 2017: BMC Neuroscience
https://www.readbyqxmd.com/read/28414224/carbanion-translocations-via-intramolecular-proton-transfers-a%C3%A2-quantum-chemical-study
#10
Yi Wang, Pei-Jun Cai, Zhi-Xiang Yu
Intramolecular proton transfers are important processes in chemical reactions and biological transformations. In particular, the translocation of reactive carbanion centers can be achieved through 1,n-proton transfer in either a direct or an assisted manner (via the protonation/deprotonation mechanism). Despite some mechanistic investigations on proton transfers within zwitterionic species, no guiding principles have been summarized for carbanion-induced intramolecular proton transfers. Herein, we report our quantum chemical study on the carbanion translocations via intramolecular proton transfers...
April 17, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28412658/cds-mn-quantum-dot-functionalized-g-c3n4-nanohybrids-as-signal-generation-tags-for-photoelectrochemical-immunoassay-of-prostate-specific-antigen-coupling-dnazyme-concatamer-with-enzymatic-biocatalytic-precipitation
#11
Kangyao Zhang, Shuzhen Lv, Zhenzhen Lin, Dianping Tang
A new photoelectrochemical (PEC) immunosensor based on Mn-doped CdS quantum dots (CdS:Mn QDs) on g-C3N4 nanosheets was developed for the sensitive detection of prostate specific antibody (PSA) in biological fluids. The signal derived from the as-synthesized Cd:Mn QDs-functionalized g-C3N4 nanohybrids via a hydrothermal method and was amplified through DNAzyme concatamers on gold nanoparticles accompanying enzymatic biocatalytic precipitation. Experimental results by UV-vis absorption spectra and photoluminescence revealed that CdS:Mn QDs/g-C3N4 nanohybrids exhibited higher photocurrent than those of CdS:Mn QDs and g-C3N4 alone...
April 12, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28411602/mapping-the-conformational-free-energy-of-aspartic-acid-in-the-gas-phase-and-in-aqueous-solution
#12
Federico Comitani, Kevin Rossi, Michele Ceriotti, M Eugenia Sanz, Carla Molteni
The conformational free energy landscape of aspartic acid, a proteogenic amino acid involved in a wide variety of biological functions, was investigated as an example of the complexity that multiple rotatable bonds produce even in relatively simple molecules. To efficiently explore such a landscape, this molecule was studied in the neutral and zwitterionic forms, in the gas phase and in water solution, by means of molecular dynamics and the enhanced sampling method metadynamics with classical force-fields. Multi-dimensional free energy landscapes were reduced to bi-dimensional maps through the non-linear dimensionality reduction algorithm sketch-map to identify the energetically stable conformers and their interconnection paths...
April 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28402621/specific-imaging-of-intracellular-lipid-droplets-using-a-benzothiadiazole-derivative-with-solvatochromic-properties
#13
Hanna Appelqvist, Kati Stranius, Karl Börjesson, K Peter R Nilsson, Christine Dyrager
Altered lipid metabolism and extensive lipid storage in cells has been associated with various medical disorders, including cancer. The development of fluorescent probes that specifically accumulates in lipid deposits are therefore of great interest in order to study pathological processes that are linked to dysregulated lipogenesis. In the present study, we present a small fluorescent benzothiadiazole dye that specifically stains lipid droplets in living and fixated cells. The photophysical characterization of the probe revealed strong solvatochromic behaviour, large Stokes shifts and high fluorescent quantum yields in hydrophobic solvents...
April 12, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28394560/green-rapid-and-universal-preparation-approach-of-graphene-quantum-dots-under-ultraviolet-irradiation
#14
Jinli Zhu, Yanfeng Tang, Gang Wang, Jiarong Mao, Zhiduo Liu, Tongming Sun, Miao Wang, Da Chen, Yucheng Yang, Jipeng Li, Yuan Deng, Siwei Yang
It is of great significance and importance to develop a mild, clean and high-efficient universal approach for the preparation of graphene quantum dots (GQDs) without by-products. Here, we introduce a new green, rapid and universal preparation approach for GQDs via the free radical polymerization of oxygen containing aromatic compounds under ultraviolet irradiation. The approach had a high yield (83 %) and no by-products. The obtained GQDs were well-crystallized and showed remarkable optical and biological properties...
April 10, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28393943/enhancing-coupled-enzymatic-activity-by-conjugating-one-enzyme-to-a-nanoparticle
#15
James N Vranish, Mario G Ancona, Eunkeu Oh, Kimihiro Susumu, Igor L Medintz
Enzymes have long been a prime research target for the commercial production of commodity and specialty chemicals, design of sensing devices, and the development of therapeutics and new chemical processes. Industrial applications for enzymes can potentially be enhanced by enzyme immobilization which often allows for increased enzyme stability, facile product purification, and minimized substrate diffusion times in multienzymatic cascades, but this is usually at the cost of a significant decrease in catalytic rates...
April 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28392224/the-non-equilibrium-basis-of-turing-instability-and-localised-biological-work
#16
REVIEW
Yoram Schiffmann
Turing's theory for biological pattern formation is based on the instability of the homogeneous state, which occurs if certain key criteria are met. The problem of how localised chemical energy is converted to localised biological work requires one to understand not only the basis of localised power generation, but also the age-old puzzle of how organisms decrease their entropy; these problems can only be solved by the identification of the Turing Instability. At the heart of this is how natural selection, not chemistry, has fashioned the large non-equilibrium overall affinity (ΔG is a large negative quantity) for the oxidation of the fuel molecules...
April 6, 2017: Progress in Biophysics and Molecular Biology
https://www.readbyqxmd.com/read/28390322/simple-and-highly-selective-detection-of-arsenite-based-on-the-assembly-induced-fluorescence-enhancement-of-dna-quantum-dots
#17
Li Zhang, Xiu-Zhi Cheng, Lan Kuang, Ai-Zhen Xu, Ru-Ping Liang, Jian-Ding Qiu
Novel fluorescent DNA quantum dots (QDs) were synthesized by hydrothermal treatment of G-/T-rich ssDNA at relatively low reaction temperature. The obtained DNA QDs demonstrate unique optical properties, maintain the basic structure and biological activities of ssDNA precursors, which makes the DNA QDs able to specifically bind with arsenite, driving the (GT)29 region suffer conformation evolution and form well-ordered assembly rather than random aggregations. We speculate that the strong inter-molecule interaction and efficient stacking of base pairs stiffen the assembly structure, block the nonradiative relaxation channels, populate the radiative decay, and thus making the assembly be highly emissive as a new fluorescence center...
March 30, 2017: Biosensors & Bioelectronics
https://www.readbyqxmd.com/read/28379242/aggregation-behavior-of-novel-heptamethine-cyanine-dyes-upon-their-binding-to-native-and-fibrillar-lysozyme
#18
Kateryna Vus, Ulyana Tarabara, Atanas Kurutos, Olga Ryzhova, Galyna Gorbenko, Valeriya Trusova, Nikolai Gadjev, Todor Deligeorgiev
Two newly synthesized symmetrical heptamethine cyanine dyes, AK7-5 and AK7-6, absorbing in the region of low autofluorescence of biological samples, have been tested for their ability to detect proteins aggregated into amyloid fibrils. In aqueous solution these probes possess three absorption bands corresponding to the monomer, dimer and H-aggregate species. The association of the dye with fibrillar lysozyme was followed by the enhancement of the monomer band and the reduction of the H-band. The absorption spectra measured at various fibril concentrations were analyzed in terms of the model allowing for the shift of equilibria between various dye species due to the binding of monomers and dimers of AK7-5 and AK7-6 to amyloid fibrils...
April 5, 2017: Molecular BioSystems
https://www.readbyqxmd.com/read/28378788/precise-through-space-control-of-an-abiotic-electrophilic-aromatic-substitution-reaction
#19
Kyle E Murphy, Jessica L Bocanegra, Xiaoxi Liu, H-Y Katharine Chau, Patrick C Lee, Jianing Li, Severin T Schneebeli
Nature has evolved selective enzymes for the efficient biosynthesis of complex products. This exceptional ability stems from adapted enzymatic pockets, which geometrically constrain reactants and stabilize specific reactive intermediates by placing electron-donating/accepting residues nearby. Here we perform an abiotic electrophilic aromatic substitution reaction, which is directed precisely through space. Ester arms-positioned above the planes of aromatic rings-enable it to distinguish between nearly identical, neighbouring reactive positions...
April 5, 2017: Nature Communications
https://www.readbyqxmd.com/read/28378115/tracing-tellurium-and-its-nanostructures-in-biology
#20
REVIEW
Bijan Zare, Mohammad Nami, Ahmad-Reza Shahverdi
Tellurium (Te) is a semimetal rare element in nature. Together with oxygen, sulfur (S), and selenium (Se), Te is considered a member of chalcogen group. Over recent decades, Te applications continued to emerge in different fields including metallurgy, glass industry, electronics, and applied chemical industries. Along these lines, Te has recently attracted research attention in various fields. Though Te exists in biologic organisms such as microbes, yeast, and human body, its importance and role and some of its potential implications have long been ignored...
April 4, 2017: Biological Trace Element Research
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