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https://www.readbyqxmd.com/read/28930327/microscopic-rigidity-and-heterogeneity-of-ionic-liquids-probed-by-stochastic-molecular-librations-of-the-dissolved-nitroxides
#1
Mikhail Yu Ivanov, Olesya A Krumkacheva, Sergei A Dzuba, Matvey V Fedin
Microscopic molecular organization and heterogeneities in ionic liquids (ILs) are of significant fundamental and applied interest. Although many theoretical studies have been dedicated to this topic, the development of experimental methods for studying such heterogeneities is still in demand. In this work we propose a new approach for the characterization of microscopic rigidity and heterogeneities in ILs using stochastic librations (small angle motions) of the nitroxide radicals as a probe. Stable nitroxides are dissolved in ILs, which are then shock-frozen and investigated using pulse Electron Paramagnetic Resonance (EPR) at variable temperatures...
September 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28926231/resonance-emission-enhancement-ree-for-narrow-band-red-emitting-a2gef6-mn-4-a-na-k-rb-cs-phosphors-synthesized-via-a-precipitation-cation-exchange-route
#2
Hongzhou Lian, Qingming Huang, Yeqing Chen, Kai Li, Sisi Liang, Mengmeng Shang, Manman Liu, Jun Lin
Narrow band red-emitting A2GeF6:Mn(4+) (A = Na, K, Rb, Cs) phosphors were prepared through a two-step precipitation-cation exchange route using a K2MnF6 precursor as the Mn(4+) source. The phase purity, morphology, and constituent were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectric spectroscopy (XPS), and electron paramagnetic resonance (EPR) examination. Optical properties were investigated by photoluminescence spectra (PL and PLE) and high-resolution PL. A temperature-dependent PL examination was performed to investigate the electron-phonon coupling emission mechanism of Mn(4+) in these alkali fluorogermanates...
September 19, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28926225/bridging-bio-nano-science-and-cancer-nanomedicine
#3
Mattias Björnmalm, Kristofer J Thurecht, Michael Michael, Andrew M Scott, Frank Caruso
The interface of bio-nano science and cancer medicine is an area experiencing much progress but also beset with controversy. Core concepts of the field-e.g., the enhanced permeability and retention (EPR) effect, tumor targeting and accumulation, and even the purpose of "nano" in cancer medicine-are hotly debated. In parallel, considerable advances in neighboring fields are occurring rapidly, including the recent progress of "immuno-oncology" and the fundamental impact it is having on our understanding and the clinical treatment of the group of diseases collectively known as cancer...
September 19, 2017: ACS Nano
https://www.readbyqxmd.com/read/28924898/formation-of-tyrosine-radicals-in-photosystem-ii-under-far-red-illumination
#4
Nigar Ahmadova, Fikret Mamedov
Photosystem II (PS II) contains two redox-active tyrosine residues on the donor side at symmetrical positions to the primary donor, P680. TyrZ, part of the water-oxidizing complex, is a preferential fast electron donor while TyrD is a slow auxiliary donor to P680(+). We used PS II membranes from spinach which were depleted of the water oxidation complex (Mn-depleted PS II) to study electron donation from both tyrosines by time-resolved EPR spectroscopy under visible and far-red continuous light and laser flash illumination...
September 18, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28923402/synergistic-chemo-photodynamic-therapy-by-big-small-combo-nanoparticles-sequential-release-system
#5
Li Fan, Saisai Zhao, Xin Jin, Yongsheng Zhang, Chaojun Song, Hong Wu
Chemo-photodynamic combination has been manifested great potential for synergistic cancer therapy. Moreover, the synergistic efficacy could be significantly enhanced by well designed sequential release manner of photosensitizers (PSs). Here we propose a "Big & small combo nanoparticles (NPbig&small)" system for double loading PSs methylene blue (MB) and single absorbing chemotherapeutics drug Gemcitabine hydrochloride (GM(.)HCl). The "grown-in" MB from NPbig&small show two-peak sequential release profile, significantly improve the absorbed chemo therapeutic efficacy of GM(...
September 15, 2017: Nanomedicine: Nanotechnology, Biology, and Medicine
https://www.readbyqxmd.com/read/28921983/the-first-state-in-the-catalytic-cycle-of-the-water-oxidizing-enzyme-identification-of-a-water-derived-%C3%AE-hydroxo-bridge
#6
Thomas Lohmiller, Vera Krewald, Arezki Sedoud, A William Rutherford, Frank Neese, Wolfgang Lubitz, Dimitrios A Pantazis, Nicholas Cox
Nature's water splitting catalyst, an oxygen-bridged tetra-manganese calcium (Mn4O5Ca) complex, sequentially activates two substrate water molecules generating molecular O2. Its reaction cycle is composed of five intermediate (Si) states, where the index i indicates the number of oxidizing equivalents stored by the cofactor. After formation of the S4 state, the product dioxygen is released and the cofactor returns to its lowest oxidation state, S0. Membrane-inlet mass spectrometry measurements suggest that at least one substrate is bound throughout the catalytic cycle, as the rate of (18)O-labeled water incorporation into the product O2 is slow, on a millisecond to second timescale depending on the S state...
September 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28920698/correlating-bridging-ligand-with-properties-of-ligand-templated-mn-ii-3x3-3-clusters-x-br-cl-h-meo
#7
Kevin J Anderton, David M Ermert, Pedro A Quintero, Mackenzie W Turvey, Majed S Fataftah, Khalil A Abboud, Mark W Meisel, Erik Čižmár, Leslie J Murray
Polynuclear manganese compounds have garnered interest as mimics and models of the water oxidizing complex (WOC) in photosystem II and as single molecule magnets. Molecular systems in which composition can be correlated to physical phenomena, such as magnetic exchange interactions, remain few primarily because of synthetic limitations. Here, we report the synthesis of a family of trimanganese(II) complexes of the type Mn3X3L (X = Cl(-), H(-), and MeO(-)) where L(3-) is a tris(β-diketiminate) cyclophane. The tri(chloride) complex (2) is structurally similar to the reported tri(bromide) complex (1) with the Mn3X3 core having a ladder-like arrangement of alternating M-X rungs, whereas the tri(μ-hydride) (3) and tri(μ-methoxide) (4) complexes contain planar hexagonal cores...
September 18, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28919745/dose-and-time-effect-of-cdte-quantum-dots-on-antioxidant-capacities-of-the-liver-and-kidneys-in-mice
#8
Jilong Wang, Hubo Sun, Peijun Meng, Mengmeng Wang, Mi Tian, Yamin Xiong, Xueying Zhang, Peili Huang
Although quantum dot (QD)-induced toxicity occurs due to free radicals, generation of oxidative stress mediated by reactive oxygen species (ROS) formation is considered an important mechanism. However, free radical mechanisms are essentially difficult to elucidate at the molecular level because most biologically relevant free radicals are highly reactive and short-lived, making them difficult to directly detect, especially in vivo. Antioxidants play an important role in preventing or, in most cases, limiting the damage caused by ROS...
2017: International Journal of Nanomedicine
https://www.readbyqxmd.com/read/28917853/preparation-and-biological-activity-studies-of-resveratrol-loaded-ionically-cross-linked-chitosan-tpp-nanoparticles
#9
Jie Wu, Yaping Wang, Hao Yang, Xiangyu Liu, Zhong Lu
Nanoparticles with size range of 10-500nm can be efficiently delivered into cancer cells by the Enhanced Permeability and Retention (EPR) effect. Here, we prepared resveratrol (Res) loaded chitosan (CS) nanoparticles with the size of 172-217nm by an ionic cross-linking method, with sodium tripolyphosphate (TPP) as the cross-linking agent, to improve the stability, solubility and tumors targeting of the natural anti-cancer drug Res. The prepared Res loaded CS-TPP nanoparticles presented long-term storage stability and UV light stability...
November 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28917532/effects-of-tumor-microenvironments-on-targeted-delivery-of-glycol-chitosan-nanoparticles
#10
Ji Young Yhee, Sangmin Jeon, Hong Yeol Yoon, Man Kyu Shim, Hyewon Ko, Jiwoong Min, Jin Hee Na, Hyeyoun Chang, Hyounkoo Han, Jong-Ho Kim, Minah Suh, Hyukjin Lee, Jae Hyung Park, Kwangmeyung Kim, Ick Chan Kwon
In cancer theranostics, the main strategy of nanoparticle-based targeted delivery system has been understood by enhanced permeability and retention (EPR) effect of macromolecules. Studies on diverse nanoparticles provide a better understanding of different EPR effects depending on their structure, physicochemical properties, and chemical modifications. Recently the tumor microenvironment has been considered as another important factor for determining tumor-targeted delivery of nanoparticles, but the correlation between EPR effects and tumor microenvironment has not yet been fully elucidated...
September 13, 2017: Journal of Controlled Release: Official Journal of the Controlled Release Society
https://www.readbyqxmd.com/read/28916593/carnosic-acid-and-carnosol-two-major-antioxidants-of-rosemary-act-through-different-mechanisms
#11
Margot Loussouarn, Anja Krieger-Liszkay, Ljubica Svilar, Antoine Bily, Simona Birtic, Michel Havaux
Carnosic acid, a phenolic diterpene specific of the Lamiaceae family, is highly abundant in rosemary species. Despite numerous industrial and medicinal/pharmaceutical applications of its antioxidative features, this compound in planta and its antioxidant mechanism have received little attention, except a few studies of rosemary plants under natural conditions. In vitro analyses, using HPLC-UV and luminescence imaging, revealed that carnosic acid and its major oxidized derivative, carnosol, protect lipids from oxidation...
September 15, 2017: Plant Physiology
https://www.readbyqxmd.com/read/28916497/two-step-polymer-and-liposome-enzyme-prodrug-therapies-for-cancer-pdept-and-pelt-concepts-and-future-perspectives
#12
Anna Scomparin, Helena F Florindo, Galia Tiram, Elaine L Ferguson, Ronit Satchi-Fainaro
Polymer-directed enzyme prodrug therapy (PDEPT) and polymer enzyme liposome therapy (PELT) are two-step therapies developed to provide anticancer drugs site-selective intratumoral accumulation and release. Nanomedicines, such as polymer-drug conjugates and liposomal drugs, accumulate in the tumor site due to extravasation-dependent mechanism (enhanced permeability and retention - EPR - effect), and further need to cross the cellular membrane and release their payload in the intracellular compartment. The subsequent administration of a polymer-enzyme conjugate able to accumulate in the tumor tissue and to trigger the extracellular release of the active drug showed promising preclinical results...
September 12, 2017: Advanced Drug Delivery Reviews
https://www.readbyqxmd.com/read/28916358/the-functional-characterization-and-comparison-of-two-single-crd-containing-c-type-lectins-with-novel-and-typical-key-motifs-from-portunus-trituberculatus
#13
Mengmeng Huang, Changkao Mu, Yuehong Wu, Fei Ye, Dan Wang, Cong Sun, Zhengbing Lv, Bingnan Han, Chunlin Wang, Xue-Wei Xu
C-type lectins are a superfamily of Ca(2+)-dependent carbohydrate-recognition proteins, which play crucial roles in innate immunity including nonself-recognition and pathogen elimination. In the present study, two single-CRD containing C-type lectins were identified from swimming crab Portunus trituberculatus (designated as PtCTL-2 and PtCTL-3). The open reading frame (ORF) of PtCTL-2 encoded polypeptides of 485 amino acids with a signal peptide and a single carbohydrate-recognition domain (CRD), while PtCTL-3's ORF encoded polypeptides of 241 amino acids with a coiled-coil region and a single-CRD...
September 12, 2017: Fish & Shellfish Immunology
https://www.readbyqxmd.com/read/28913528/dna-protection-by-ectoine-from-ionizing-radiation-molecular-mechanisms
#14
Marc Benjamin Hahn, Susann Meyer, Maria-Astrid Schröter, Hans-Jörg Kunte, Tihomir Solomun, Heinz Sturm
Ectoine, a compatible solute and osmolyte, is known to be an effective protectant of biomolecules and whole cells against heating, freezing and extreme salinity. Protection of cells (human keratinocytes) by ectoine against ultraviolet radiation has also been reported by various authors, although the underlying mechanism is not yet understood. We present the first electron irradiation of DNA in a fully aqueous environment in the presence of ectoine and at high salt concentrations. The results demonstrate effective protection of DNA by ectoine against the induction of single-strand breaks by ionizing radiation...
September 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28910663/strategies-for-overcoming-tropical-disease-by-ruthenium-complexes-with-purine-analog-application-against-leishmania-spp-and-trypanosoma-cruzi
#15
Marzena Fandzloch, José Manuel Méndez Arriaga, Manuel Sánchez-Moreno, Andrzej Wojtczak, Julia Jezierska, Jerzy Sitkowski, Joanna Wiśniewska, Juan Manuel Salas, Iwona Łakomska
Tropical diseases currently constitute a major health problem and thus a challenge in the field of drug discovery. The current treatments show serious disadvantages due to cost, toxicity, long therapy duration and resistance, and the use of metal complexes as chemotherapeutic agents against these ailments appears to be a very attractive alternative. Herein, we describe three newly synthesized ruthenium complexes with a bioactive molecule, the purine analogue 5,6,7-trimethyl-1,2,4-triazolo[1,5-a]pyrimidine (tmtp): cis,fac-[RuCl2(dmso)3(tmtp)] (1), mer-[RuCl3(dmso)(H2O)(tmtp)]·2H2O (2) and fac,cis-[RuCl3(H2O)(tmtp)2] (3)...
September 1, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28900511/a-nanosystem-of-amphiphilic-oligopeptide-drug-conjugate-actualizing-both-%C3%AE-v%C3%AE-3-targeting-and-reduction-triggered-release-for-maytansinoid
#16
Yanqin Liang, Suxin Li, Xiaoyou Wang, Bo He, Bing He, Wenbing Dai, Hua Zhang, Xueqing Wang, Yiguang Wang, Demin Zhou, Qiang Zhang
To design a prodrug-based self-assembling nanosystem with both ligand targeting and stimuli-responsive features, and elucidate the superiority of each targeting strategy and the synergistic effect between them, we synthesized four small molecule amphiphilic peptide-drug conjugates (APDCs) using maytansinoid (DM1) as a cytotoxic agent, cRGDfK as a homing peptide, and disulfide (SS) or thioether (SMCC) as linker. Owing to their amphiphilicity, the APDCs could self-assemble into nanoparticles (APDC@NPs) which were evaluated in vitro in three different cell lines and in vivo in tumor-bearing C57BL/6 mice...
2017: Theranostics
https://www.readbyqxmd.com/read/28899550/geometric-effects-on-oo-bond-scission-of-copper-ii-alkylperoxide-complexes
#17
Tsukasa Abe, Yuma Morimoto, Kaoru Mieda, Hideki Sugimoto, Nobutaka Fujieda, Takashi Ogura, Shinobu Itoh
Copper(II) complexes supported by N3-tridentate ligands, consisting of a rigid cyclic diamine (8-membered cyclic-diamine; L8 or 7-membered cyclic-diamine; L7) and a 2-(2-pyridyl)ethyl (-CH2CH2Py) group, were synthesized and structurally characterized. Reaction of the copper(II) complexes and cumene hydroperoxide (CmOOH) in the presence of triethylamine in CH3CN gave the corresponding cumylperoxide complexes L8Cu(II)OOCm and L7Cu(II)OOCm. The UV-vis and EPR spectra suggested that L8Cu(II)OOCm takes a tetrahedrally distorted structure, whereas L7Cu(II)OOCm has a planar geometry in solution...
September 1, 2017: Journal of Inorganic Biochemistry
https://www.readbyqxmd.com/read/28898862/degradation-and-intermediates-of-diclofenac-as-instructive-example-for-decomposition-of-recalcitrant-pharmaceuticals-by-hydroxyl-radicals-generated-with-pulsed-corona-plasma-in-water
#18
Robert Banaschik, Helena Jablonowski, Patrick J Bednarski, Juergen F Kolb
Seven recalcitrant pharmaceutical residues (diclofenac, 17α-ethinylestradiol, carbamazepine, ibuprofen, trimethoprim, diazepam, diatrizoate) were decomposed by pulsed corona plasma generated directly in water. The detailed degradation pathway was investigated for diclofenac and 21 intermediates could be identified in the degradation cascade. Hydroxyl radicals have been found primarily responsible for decomposition steps. By spin trap enhanced electron paramagnetic resonance spectroscopy (EPR), OH-adducts and superoxide anion radical adducts were detected and could be distinguished applying BMPO as a spin trap...
August 25, 2017: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/28898478/electrocatalytic-azide-oxidation-mediated-by-a-rh-pnp-pincer-complex
#19
Bas de Bruin, Christophe Rebreyend, Yann Gloaguen, Martin Lutz, Jarl Ivar van der Vlugt, Inke Siewert, Sven Schneider
One-electron oxidation of the rhodium(I) azido complex [Rh(N3)(PNP)] (5), bearing the neutral PNP ligand 2,6-bis(di-tert-butylphosphinomethyl)pyridine leads to instantaneous and selective formation of the mononuclear rhodium(I) dinitrogen complex [Rh(N2)(PNP)]+ (9+). Interestingly, complex 5 also acts as a catalyst for electrochemical N3- oxidation in the presence of excess azide at a substantially lower potential (Ep ~ -0.23 V vs. Fc+/0) than direct oxidation at Pt-electrodes (Ep ~ +0.19 V vs. Fc+/0). Cyclic voltammetry in the presence of an excess of N(nBu)4N3 reveals that electro-catalytic N3-oxidation occurs at roughly the same potential as the first oxidation wave of 5...
September 12, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28898098/substituent-effects-on-the-coordination-chemistry-of-metal-binding-pharmacophores
#20
Whitney R Craig, Tessa W Baker, Amy R Marts, Daniel T DeGenova, David P Martin, Garrett C Reed, Robert M McCarrick, Michael W Crowder, Seth M Cohen, David L Tierney
A combination of XAS, UV-vis, NMR, and EPR was used to examine the binding of a series of α-hydroxythiones to CoCA. All three appear to bind preferentially in their neutral, protonated forms. Two of the three clearly bind in a monodentate fashion, through the thione sulfur alone. Thiomaltol (TM) appears to show some orientational preference, on the basis of the NMR, while it appears that thiopyromeconic acid (TPMA) retains rotational freedom. In contrast, allothiomaltol (ATM), after initially binding in its neutral form, presumably through the thione sulfur, forms a final complex that is five-coordinate via bidentate coordination of ATM...
September 12, 2017: Inorganic Chemistry
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