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排序方式: 共有207条查询结果,搜索用时 15 毫秒
91.
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93.
Romana Konecna Hoai Viet Nguyen Maja Stanisavljevic Iva Blazkova Sona Krizkova Marketa Vaculovicova Marie Stiborova Tomas Eckschlager Ondrej Zitka Vojtech Adam Rene Kizek 《Chromatographia》2014,77(21-22):1469-1476
Doxorubicin (DOX) belongs to the group of anthracycline antibiotics with very effective anticancer properties. On the other hand, the cardiotoxic effects limit its application over the maximum cumulative dose. To overcome this obstacle, encapsulation of this drug into the protective nanotransporter such as apoferritin is beneficial. In this study, fluorescent behavior of DOX in various solvents was determined by fluorescence spectrometry, demonstrating the fluorescence quenching effect of water, which is often used as a solvent. It was found that by increasing the amount of the organic phase in the DOX solvent the dynamic quenching is significantly suppressed. Ethanol, acetonitrile and dimethyl sulfoxide were tested and the best linearity of the calibration curve was obtained when above 50 % of the solvent was present in the binary mixture with water. Moreover, pH influence on the DOX fluorescence was also observed within the range of 4–10. Two times higher fluorescence intensity was observed at pH 4 compared to pH 10. Further, the DOX behavior in capillary electrophoresis (CE) was investigated. Electrophoretic mobilities (CE) in various pH of the background electrolyte were determined within the range from 16.3 to ?13.3 × 10 ?9 m?2 V?1 s?1. Finally, CE was also used to monitor the encapsulation of DOX into the cavity of apoferritin as well as the pH-triggered release. 相似文献
94.
Ondrej Sedlacek Jan Kucka Frantisek Svec Martin Hruby 《Journal of separation science》2014,37(7):798-802
In this study, we demonstrate the preparation of a macroporous monolithic column containing anchored silver nanoparticles and its use for the elimination of excess radioiodine from the radiolabeled pharmaceutical. The poly(glycidyl methacrylate‐co‐ethylene dimethacrylate) monolith was first functionalized with cystamine and the free thiol groups liberated by reaction with borohydride. In‐house‐prepared silver nanoparticles were then attached by interaction with the surface thiols. The deiodization process was demonstrated with the commonly used radiopharmaceutical m‐iodobenzylguanidine labeled with radionuclide iodine‐125. 相似文献
95.
Sylvie Skalickova Ondrej Zitka Lukas Nejdl Sona Krizkova Jiri Sochor Libor Janu Marketa Ryvolova David Hynek Jarmila Zidkova Vaclav Zidek Vojtech Adam Rene Kizek 《Chromatographia》2013,76(7-8):345-353
Quantum dots (QDs) belong to a new class of fluorescent agent for biochemical, medicinal or other purposes. However, QDs based on cadmium or other metals can be risky for an organism. As one of the mechanism how to detoxify cadmium-based QDs expression of metallothioneins (MT) can be considered. Due to high affinity of metallothionein to cadmium(II) ions, we attempted to develop an approach for studying of possible interaction with QDs. We prepared QDs with CdTe core and studied the interaction with MT, which we isolated from livers of Cd-administered rabbits. To study the interaction, we used the mixture of both components MT (3.6 μM): CdTe QDs (0, 0.34, 0.68, 1.02, 1.36, 1.7, 2.04 and 2.47 μM). The mixtures were studied by spectrophotometry within the range from 200 to 750 nm with detected maxima at 260 and 505 nm. Same mixtures were also analysed by differential pulse voltammetry Brdicka reaction, which supported data from spectrophotometry. Subsequently, we used fast protein liquid chromatography for purification of protein–quantum dot conjugates. We obtained the different chromatograms for (1) Apo MT, (2) CdTe QDs and (3) MT–QD complex. We also collected the fractions and subsequently analysed them on the content of Cd and MT, which confirmed the formation of CdTe QDs–MT complex. 相似文献
96.
Pracna P Urban J Votava O Meltzerová Z Urban S Horneman VM Drouin BJ 《The journal of physical chemistry. A》2011,115(6):1063-1068
The parallel vibration-rotation band ν(4) of methyl isocyanide (CH(3)NC), with a band center at 944.9 cm(-1), was studied by FTIR spectroscopy between 890 and 980 cm(-1) in order to improve the ground-state rotational constants. Such improvement is essential for the scheduled studies of excited vibrational levels and their mutual anharmonic resonances occurring at higher values of the K rotational number. Ground-state combination differences generated from this band, spanning values of J/K from 0 to 85/13, were combined with rotational data from the literature and newly measured rotational transitions, extending the J/K range from 3/0 up to 31/14, and fitted simultaneously with a fully quantitative reproduction of the data. The infrared data of the ν(4) band were analyzed together with rotational data of the ν(4) = 1 level, spanning values of J/K from 4/0 to 14/12. The fit in the approximation of an isolated vibrational state, with the transitions perturbed by weak local resonances excluded, yields reproduction of the data within experimental uncertainties. 相似文献
97.
The impact of microhydration on the electronic structure and reactivity of the H(3)O moiety is investigated by ab initio calculations. In the gas phase, H(3)O is a radical with spin density localized on its hydrogen end, which is only kinetically stable and readily decomposes into a water molecule and a hydrogen atom. When solvated by a single water molecule, H(3)O preserves to a large extent its radical character, however, two water molecules are already capable to shift most of the spin density to the solvent. With three solvating water molecules this shift is practically completed and the system is best described as a solvent-separated pair of a hydronium cation and a hydrated electron. The electronic structure of this system and its proton transfer reactivity leading to formation of a hydrogen atom already resemble those of a proton-electron pair in bulk water. 相似文献
98.
Zitka O Krizkova S Huska D Adam V Hubalek J Eckschlager T Kizek R 《Electrophoresis》2011,32(8):857-860
Matrix metalloproteinases (MMPs) play numerous roles in physiological and pathological processes including cancer. Interactions of MMPs with other zinc-binding proteins are of great interest mainly from the point of view of the participation of these proteins in carcinogenesis. The aim of this study was to utilize chip gel electrophoresis for investigation of matrix metalloproteinase 9 (gelatinase B, MMP-9) interactions with collagen. The interaction was observed and the effect of temperature was tested. We further focused on the study of activation of MMP-9 by the presence of zinc-binding proteins called metallothioneins (MT). We confirmed the basic presumption of the activation of MMP-9 by the presence of MT similar to the temperature effect. Moreover, we chose the method of differential pulse voltammetry Brdicka reaction to verify our results. It can be concluded that the activity of MMP-9 was higher in the presence of MT in comparison with the experimental collagen(type I)-MMP-9 mixture in vitro. 相似文献
99.
Marsalek O Elles CG Pieniazek PA Pluhařová E VandeVondele J Bradforth SE Jungwirth P 《The Journal of chemical physics》2011,135(22):224510
The ultrafast dynamics of the cationic hole formed in bulk liquid water following ionization is investigated by ab initio molecular dynamics simulations and an experimentally accessible signature is suggested that might be tracked by femtosecond pump-probe spectroscopy. This is one of the fastest fundamental processes occurring in radiation-induced chemistry in aqueous systems and biological tissue. However, unlike the excess electron formed in the same process, the nature and time evolution of the cationic hole has been hitherto little studied. Simulations show that an initially partially delocalized cationic hole localizes within ~30 fs after which proton transfer to a neighboring water molecule proceeds practically immediately, leading to the formation of the OH radical and the hydronium cation in a reaction which can be formally written as H(2)O(+) + H(2)O → OH + H(3)O(+). The exact amount of initial spin delocalization is, however, somewhat method dependent, being realistically described by approximate density functional theory methods corrected for the self-interaction error. Localization, and then the evolving separation of spin and charge, changes the electronic structure of the radical center. This is manifested in the spectrum of electronic excitations which is calculated for the ensemble of ab initio molecular dynamics trajectories using a quantum mechanics/molecular mechanics (QM∕MM) formalism applying the equation of motion coupled-clusters method to the radical core. A clear spectroscopic signature is predicted by the theoretical model: as the hole transforms into a hydroxyl radical, a transient electronic absorption in the visible shifts to the blue, growing toward the near ultraviolet. Experimental evidence for this primary radiation-induced process is sought using femtosecond photoionization of liquid water excited with two photons at 11 eV. Transient absorption measurements carried out with ~40 fs time resolution and broadband spectral probing across the near-UV and visible are presented and direct comparisons with the theoretical simulations are made. Within the sensitivity and time resolution of the current measurement, a matching spectral signature is not detected. This result is used to place an upper limit on the absorption strength and/or lifetime of the localized H(2)O(+) ((aq)) species. 相似文献
100.
A new version of the multireference Mukherjee's coupled cluster method with perturbative triexcitations has been formulated, which is based on the uncoupled approximation applied to the triples equation. In contrast to the method developed by Evangelista et al. [J. Chem. Phys. 132, 074107 (2010)], the proposed approach does not require to solve the equation for T(3) amplitudes iteratively, yet yields results of essentially the same quality. The method, abbreviated as MR MkCCSD(Tu), has been implemented in the ACES II program package and its assessment has been performed on the BeH(2) model and on the tetramethyleneethane molecule. 相似文献