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Green chemistry

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https://www.readbyqxmd.com/read/29331797/application-of-polyacrylamide-gel-as-a-new-membrane-in-electromembrane-extraction-for-the-quantification-of-basic-drugs-in-breast-milk-and-wastewater-samples
#1
Sakine Asadi, Hadi Tabani, Saeed Nojavan
Introducing new membranes with green chemistry approach seems to be a great challenge for the development of a practical method in separation science. In this regard, for the first time, polyacrylamide gel as a new membrane in electromembrane extraction (EME) was used for the extraction of three model basic drugs (pseudoephedrine (PSE), lidocaine (LID), and propranolol (PRO)), followed by HPLC-UV. In comparison with conventional EME, in this method neither organic solvent nor carrier agents were used for extraction of mentioned drugs...
January 9, 2018: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29328673/fluorescent-proteins-detect-host-structural-rearrangements-via-electrostatic-mechanism
#2
Lena Simine, Heiko Lammert, Li Sun, Jose Nelson Onuchic, Peter J Rossky
The rational design of genetically encoded fluorescent bio-sensors, which can detect rearrangements of target proteins via interdomain allostery, is hindered by the absence of mechanistic understanding of the underlying photo-physics. Here, we focus on the modulation of fluorescence by mechanical perturbation in a popular biological probe: enhanced Green Fluorescent Protein (eGFP). Using a combination of molecular dynamics (MD) simulations and quantum chemistry, and a set of physically motivated assumptions, we construct a map of fluorescence quantum yield as a function of a 2D electric field imposed by the protein environment on the fluorophore...
January 12, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29327589/transition-metal-dichalcogenide-nanosheets-for-visual-monitoring-pcr-rivaling-a-real-time-pcr-instrument
#3
Liu Wang, Zhicheng Huang, Rui Wang, Yibo Liu, Cheng Qian, Jian Wu, Juewen Liu
Monitoring the progress of polymerase chain reactions (PCR) is of critical importance in bioanalytical chemistry and molecular biology. While real-time PCR thermocyclers are ideal for this purpose, its high cost has limited applications in resource-poor areas. Direct visual detection would be a more attractive alternative. To monitor PCR amplification, DNA staining dyes such as SYBR Green I (SG) are often used. Although these dyes give higher fluorescence when binding to double-stranded (ds) DNA products, they also yield strong background fluorescence in the presence of a high concentration of single-stranded (ss) DNA primers...
January 12, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29320632/increasing-the-stability-of-recombinant-human-green-cone-pigment
#4
Timothy S Owen, David Salom, Wenyu Sun, Krzysztof Palczewski
Three types of cone cells exist in the human retina, each containing a different pigment responsible for the initial step of photo-transduction. These pigments are distinguished by their specific absorbance maxima, 425 nm (blue), 530 nm (green) and 560 nm (red). Each pigment contains a common chromophore, 11-cis-retinal covalently bound to an opsin protein via a Schiff base. The 11-cis-retinal protonated Schiff base has an absorbance maxima at 440 nm in methanol. Unfortunately, the chemistry allowing the same chromophore interacting with different opsin proteins to tune the absorbance of the resulting pigments to distinct λmax values is poorly understood...
January 10, 2018: Biochemistry
https://www.readbyqxmd.com/read/29313428/biosynthesis-of-silver-nanoparticles-using-novel-bacillus-sp-sbt8
#5
Tuğçe Yurtluk, Fikriye Alev Akçay, Ayşe Avcı
Biosynthesis of silver nanoparticles (AgNPs) using microorganisms is an important application of nano-biotechnology and green chemistry because of interest by pharmaceutical and food manufacturers. In this study, biosynthesis of AgNPs by a novel Bacillus strain isolated from a soil sample from Sakarya district in Turkey was investigated. Biosynthesis was performed using cell-free supernatant of the bacterium following 24 h growth. Effects of varying AgNO3 concentration (1-10 mM), pH (5-10), and temperature (30-40°C) on the synthesis of AgNPs were determined...
January 9, 2018: Preparative Biochemistry & Biotechnology
https://www.readbyqxmd.com/read/29313345/cobalt-catalyzed-aerobic-cross-dehydrogenative-coupling-of-c-h-and-thiols-in-water-for-c-s-formation
#6
Xin Huang, Yongqi Chen, Shan Zhen, Lijuan Song, Mingqi Gao, Panke Zhang, Heng Li, Bingxin Yuan, Guanyu Yang
Organosulfides have great significance and value in synthetic and biological chemistry. To establish a versatile and green methodology for C-S bond generation, we successfully developed a new aerobic cross-dehydrogenative coupling of C-H and S-H to synthesize arylsulfides in water, utilizing CoPcS as the catalyst and O2 as the oxidant. This protocol shows great tolerance of a wide range of substrates. A large variety of organosulfur compounds were produced in modest to excellent yields.
January 9, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29310860/kinetic-resolution-of-sec-alcohols-catalysed-by-candida-antarctica-lipase-b-displaying-pichia-pastoris-whole-cell-biocatalyst
#7
Kun Zhang, Zhiyou Pan, Zhoujian Diao, Shuli Liang, Shuangyan Han, Suiping Zheng, Ying Lin
Kinetic resolution of sec-alcohols is a green process with biocatalyst. Candida antarctica lipase B (CALB) displayed on Pichia pastoris cell-surface (Pp-CALB) was characterized in kinetic resolution of sec-alcohols with different structures. The reaction parameters including acyl donors, molar ratio of substrates, solvents and temperatures were examined with 2-octanol as model substrate. 47.4% molar conversion of 2-octanol and 99.7% eep were obtained after a 5h reaction with Pp-CALB, and 90% of its original activity still remained after being reused for 10 cycles...
March 2018: Enzyme and Microbial Technology
https://www.readbyqxmd.com/read/29310209/highly-fluorescent-sensing-of-nitroaromatic-explosives-in-aqueous-media-using-pyrene-linked-pbema-microspheres
#8
Hamza Turhan, Ece Tukenmez, Bunyamin Karagoz, Niyazi Bicak
Crosslinked 2-bromoethyl methacrylate polymer (PBEMA) was prepared in micro-spherical form (2-5µm) by precipitation polymerization methodology. The bromide substituent was substituted with an azide group, which was then coupled with 1-[(2-Propynyloxy)methyl]pyrene] via alkyne-azide click chemistry. The pyrene-linked microspheres showed an intense green-blue excimer emission with a maximum at 480nm, implying π-π stacking between the pyrene moieties on the microsphere surfaces. This fluorescence emission is extremely sensitive to the aromatic nitro compounds...
March 1, 2018: Talanta
https://www.readbyqxmd.com/read/29306439/intracellular-imaging-of-protein-specific-glycosylation
#9
Franziska Doll, Jessica Hassenrück, Valentin Wittmann, Andreas Zumbusch
Posttranslational protein glycosylation is conserved in all kingdoms of life and implicated in the regulation of protein structure, function, and localization. The visualization of glycosylation states of designated proteins within living cells is of great importance for unraveling the biological roles of intracellular protein glycosylation. Our generally applicable approach is based on the incorporation of a glucosamine analog, Ac4GlcNCyoc, into the cellular glycome via metabolic engineering. Ac4GlcNCyoc can be labeled in a second step via inverse-electron-demand Diels-Alder chemistry with fluorophores inside living cells...
2018: Methods in Enzymology
https://www.readbyqxmd.com/read/29302970/tailor-making-fluorescent-hyaluronic-acid-microgels-via-combining-microfluidics-and-photoclick-chemistry-for-sustained-and-localized-delivery-of-herceptin-in-tumor
#10
Jing Chen, Ke Huang, Qijun Chen, Chao Deng, Jian Zhang, Zhiyuan Zhong
Antibody therapeutics though representing a most used biomedicine suffers from poor in vivo stability, rapid degradation, and frequent injections. Here, we report that fluorescent hyaluronic acid microgels (HMGs) tailor-made by combining microfluidics and "tetrazole-alkene" photoclick chemistry enable sustained and localized delivery of Herceptin in ovarian tumor. HMGs were obtained with defined size (25-50 μm), narrow size distribution, high stability, and strong green fluorescence. Notably, HMGs exhibited a remarkably high loading of proteins like Herceptin and IgG with a loading efficiency exceeding 90% at a theoretical protein loading content of 30 wt...
January 5, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29300059/probing-the-effect-of-different-graphitic-nitrogen-sites-on-the-aerobic-oxidation-of-thiols-to-disulfides-a-dft-study
#11
J Vijaya Sundar, M Kamaraj, V Subramanian
Functionalized graphene materials are well known for their application in catalyzing the aerobic oxidation of alcohols, hydrocarbons, etc. in an aqueous medium. Despite the fact that a few catalysts are known to oxidize thiols to disulfides, their selectivity is poor and requires oxidants that are not suitable in terms of the principles of green chemistry. Therefore, in this context, an attempt has been made to investigate the possibility of utilizing nitrogen doped graphene for the aerobic oxidation of thiols to disulfides using density functional theory (DFT)...
January 4, 2018: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29287089/discovery-of-novel-orally-bioavailable-antileishmanial-compounds-using-phenotypic-screening
#12
Diana Ortiz, W Armand Guiguemde, Jared T Hammill, Angela K Carrillo, Yizhe Chen, Michele Connelly, Kayla Stalheim, Carolyn Elya, Alex Johnson, Jaeki Min, Anang Shelat, David C Smithson, Lei Yang, Fangyi Zhu, R Kiplin Guy, Scott M Landfear
Leishmaniasis is a parasitic infection that afflicts approximately 12 million people worldwide. There are several limitations to the approved drug therapies for leishmaniasis, including moderate to severe toxicity, growing drug resistance, and the need for extended dosing. Moreover, miltefosine is currently the only orally available drug therapy for this infection. We addressed the pressing need for new therapies by pursuing a two-step phenotypic screen to discover novel, potent, and orally bioavailable antileishmanials...
December 29, 2017: PLoS Neglected Tropical Diseases
https://www.readbyqxmd.com/read/29282887/air-assisted-dispersive-liquid-liquid-microextraction-based-on-a-new-hydrophobic-deep-eutectic-solvent-for-the-preconcentration-of-benzophenone-type-uv-filters-from-aqueous-samples
#13
Dandan Ge, Yi Zhang, Yixiu Dai, Shumin Yang
Deep eutectic solvents are considered as new and green solvents that can be widely used in analytical chemistry such as microextraction. In the present work, a new dl-menthol-based hydrophobic deep eutectic solvent was synthesized and used as extraction solvents in an air-assisted dispersive liquid-liquid microextraction method for preconcentration and extraction of benzophenone-type UV filters from aqueous samples followed by high-performance liquid chromatography with diode array detection. In an experiment, the deep eutectic solvent formed by dl-menthol and decanoic acid was added to an aqueous solution containing the UV filters, and then the mixture was sucked up and injected five times by using a glass syringe, and a cloudy state was achieved...
December 28, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/29260812/the-hydrolysis-of-epoxides-catalyzed-by-inorganic-ammonium-salts-in-water-kinetic-evidence-for-hydrogen-bond-catalysis
#14
B Nozière, F Fache, A Maxut, B Fenet, A Baudouin, L Fine, C Ferronato
Naturally-occurring inorganic ammonium ions have been recently reported as efficient catalysts for some organic reactions in water, which contributes to the understanding of the chemistry in some natural environments (soils, seawater, atmospheric aerosols, …) and biological systems, and is also potentially interesting for green chemistry as many of their salts are cheap and non-toxic. In this work, the effect of NH4+ ions on the hydrolysis of small epoxides in water was studied kinetically. The presence of NH4+ increased the hydrolysis rate by a factor of 6 to 25 compared to pure water and these catalytic effects were shown not to result from other ions, counter-ions or from acid or base catalysis, general or specific...
December 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29251504/cellulosic-nanomaterials-in-food-and-nutraceutical-applications-a-review
#15
Avik Khan, Yangbing Wen, Tanzina Huq, Yonghao Ni
Cellulosic nanomaterials (CNMs) are organic, green nanomaterials that are obtained from renewable sources and possess exceptional mechanical strength, and biocompatibility. The associated unique physical and chemical properties have made these nanomaterials an intriguing prospect for various applications including the food and nutraceutical industry. From the immobilization of various bioactive agents and enzymes, emulsion stabilization, direct food additives, to the development of intelligent packaging systems or pathogen or pH detectors, the potential food related applications for CNMs are endless...
December 18, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/29250615/the-bethe-salpeter-equation-in-chemistry-relations-with-td-dft-applications-and-challenges
#16
REVIEW
Xavier Blase, Ivan Duchemin, Denis Jacquemin
We review the many-body Green's function Bethe-Salpeter equation (BSE) formalism that is rapidly gaining importance for the study of the optical properties of molecular organic systems. We emphasize in particular its similarities and differences with time-dependent density functional theory (TD-DFT), both methods sharing the same formal O(N4) computing time scaling with system size. By comparison with higher level wavefunction based methods and experimental results, the advantages of BSE over TD-DFT are presented, including an accurate description of charge-transfer states and an improved accuracy for the challenging cyanine dyes...
December 18, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/29248515/limonia-acidissima-l-leaf-mediated-synthesis-of-silver-and-zinc-oxide-nanoparticles-and-their-antibacterial-activities
#17
Bheemanagouda N Patil, T C Taranath
Green chemistry is a novel method for the synthesis of silver and zinc oxide nanoparticles. The present investigation focused on synthesis of biogenic silver and zinc oxide nanoparticles. They were assayed for their antibacterial activities against test bacterial species. The results revealed that the silver nanoparticles showed the maximum zone of inhibition 15.16, 15.5 and 13.33 mm at 400 μg/mL to S. aureus, S. typhi and P. aeruginosa respectively, when compared to the Erythromycin. While zinc oxide nanoparticles showed less activity in comparison to silver nanoparticles owing to the agglomeration of nanoparticles...
December 14, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/29244950/bio-inspired-assembly-of-carbon-nanotube-into-graphene-aerogel-with-cabbage-like-hierarchical-porous-structure-for-highly-efficient-organic-pollutants-cleanup
#18
Wenwei Zhan, Siruo Yu, Liang Gao, Feng Wang, Xue Fu, Gang Sui, Xiaoping Yang
Nowadays, physical absorption has become a feasible method offering an efficient and green route to remove organic pollutants from the industrial wastewater. Inspired by polydopamine (PDA) chemistry, one dimensional PDA functionalized multi-walled carbon nanotubes (MWCNT-PDA) were creatively introduced into graphene aerogel framework to synthesis a robust graphene/MWCNT-PDA composite aerogel (GCPCA). The whole forming process needed no additional reducing agents, significantly reducing the contamination emissions to the environment...
December 15, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29244501/origins-of-enzyme-catalysis-experimental-findings-for-c-h-activation-new-models-and-their-relevance-to-prevailing-theoretical-constructs
#19
Judith P Klinman, Adam R Offenbacher, Shenshen Hu
The physical basis for enzymatic rate accelerations is a subject of great fundamental interest and of direct relevance to areas that include the de novo design of green catalysts and the pursuit of new drug regimens. Extensive investigations of C-H activating systems have provided considerable insight into the relationship between an enzyme's overall structure and the catalytic chemistry at its active site. This Perspective highlights recent experimental data for two members of distinct, yet iconic C-H activation enzyme classes, lipoxygenases and prokaryotic alcohol dehydrogenases...
December 15, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29243400/highly-efficient-gas-phase-oxidation-of-renewable-furfural-to-maleic-anhydride-over-plate-vpo-catalyst
#20
Yugen Zhang, Xiukai Li, Jogie Ko
Maleic anhydride (MAnh) and its acids are critical intermediates in chemical industry. The synthesis of maleic anhydride from renewable furfural is one of the most sought after processes in the field of sustainable chemistry. We report a plate vanadium phosphorous oxide (VPO) catalyst synthesized by a hydrothermal method with glucose as a green reducing agent for furfural oxidation to MAnh in gas phase. The plate VPOHT catalyst has a preferentially exposed 200 crystal plane and exhibited dramatically enhanced activity, selectivity and stability as compared to conventional VPO catalysts and other state-of-the-art catalytic systems...
December 15, 2017: ChemSusChem
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