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The goal of the present study is to elucidate the intragastrointestinal fate of micellar delivery systems by monitoring fluorescently labeled different micelles and the model drug paclitaxel (PTX). Both in vitro and ex vivo leakage studies showed fast PTX release in fluids while micelles remained intact, except in fed-state simulated intestinal fluid and fasted-state pig intestinal fluid, thus referring to the intact absorption of micelles and PTX leakage in the gastrointestinal tract with d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) micelles showing higher stability than other micelles. All groups of micelles were absorbed intact in Caco-2 and Caco-2/HT29-MTX cell models and the absorption of TPGS micelles was found to be higher than other micelles. The transport of the micelles across Caco-2/Raji (1.6%–3.5%), Caco-2 (0.8%–1%), and Caco-2/HT29-MTX (0.58%–1%) cell monolayers further verified the absorption of micelles and their subsequent transport; however, more TPGS micelles transported across cell monolayers than other groups. Moreover, the histological examination also confirmed that micelles entered the enterocytes and were transported to basolateral tissues and TPGS showed the stronger ability of penetration than other groups. Thus, these results are succinctly presenting the absorption of intact micelles in GIT confirmed by imaging evidence with prior leakage of the drug, uptake by enterocytes and the transport of micelles that survive the digestion by enterocytes and mainly by microfold cells in material nature dependent way with TPGS showing better results than other groups. In conclusion, these results identify the mechanism by which the gastrointestinal tract processes micelles and point to the likely use of this approach in the design of micelles-based therapies. 相似文献
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微波照射下氰基亚甲基膦叶立德和芳醛可顺利发生Wittig反应,反应具有反应时间短,立体选择性高的特点,以较高产率生成(2E)-α,β-不饱和腈. 相似文献
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1D composite nanofibers of poly(vinylpyrrolidone) (PVP, MW≈60,000) doped with three Er(III) complexes were prepared by electrospinning. They demonstrated strong near-infrared (NIR) photoluminescence (PL) at 1535 nm and ternary Er(TTA)3Phen (denoted as Er2, where TTA=2-thenoyltrifluoroacetonate; Phen=1,10-phenanthroline) fibers (Er2/PVP) exhibited maximum PL intensity. The crystal structure of Er2 complex has been determined by X-ray diffraction measurements. Er2 doped in fibers exhibited better thermal stability of NIR PL than the pure Er2 complex. These luminescent composite fibers have potential application in optical amplifiers. 相似文献
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异构化催化剂Pd/HM结炭失活研究 总被引:1,自引:0,他引:1
本文研究了正已烷异构化反应中双功能催化剂Pd/HM的结碳部位及反应条件、反应时间对催化剂结炭的影响。结果表明:催化剂金属和酸性中心均有结炭现象,金属中心先结炭,且比酸中心上结炭容易除去。两中心上结炭数量及除去难度都随反应条件的变化而增加,尤其是酸中心,这一现象与延长反应时间带来的影响是一致的。 相似文献
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Palligarnai T. Vasudevan Luting Olivia Li 《Applied biochemistry and biotechnology》1996,60(3):203-215
Studies of the kinetic behavior of horseradish peroxidase (HRP) at pH 8 and at room temperature indicate that the reaction
of phenol with H2O2 catalyzed by HRP exhibits normal Michaelis-Menten saturation kinetics. An irreversible reaction mechanism for the steady-state
kinetics of HRP, which is consistent with the experimental data, is considered. The second-order rate constants for the reactions
of HRP with H2O2 and compound II with phenol are 4.14 × 105 M-1s-1 and 5.54 × 104M-1s-1, respectively. 相似文献
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We consider a transport setup that contains a double-dot connected by a continuum. Via an exact solution of the time-dependent Schrödinger equation, we demonstrate a highly non-Markovian quantum-coherence-mediated transport through this dot–continuum–dot (DCD) system, which is in contrast with the common premise since in typical case a quantum particle does not reenter the system of interest once it irreversibly decayed into a continuum (such as the spontaneous emission of a photon). We also find that this DCD system supports an unusual steady state with unequal source and drain currents, owing to electrons irreversibly entering the continuum and floating there. 相似文献
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effect of horseradish peroxidase (HRP) and H2O2 concentrations on the removal efficiency of phenol, defined as the percentage of phenol removed from solution as a function
of time, has been investigated. When phenol and H2O2 react with an approximately one-to-one stoichiometry, the phenol is almost completely precipitated within 10 min. The reaction
is inhibited at higher concentrations of H2O2. The removal efficiency increases with an increase in the concentration of HRP, but an increase in the time of treatment
cannot be used to offset the reduction in removal efficiency at low concentrations of the enzyme, because of inactivation
of the enzyme. One molecule of HRP is needed to remove approximately 1100 molecules of phenol when the reaction is conducted
at pH 8.0 and at ambient temperature. 相似文献