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91.
Christine Vauthier Peter Lindner Bernard Cabane 《Colloids and surfaces. B, Biointerfaces》2009,69(2):207-215
The configuration of BSA macromolecules adsorbed on the surfaces of poly(alkylcyanoacrylate) nanoparticles has been determined using small angle neutron scattering (SANS). The nanoparticles were made by anionic emulsion polymerization (AEP) and self-assembly of dextran–poly(isobutylcyanoacrylate) (PICBA) copolymers. They have a hydrophobic PICBA core and a hydrophilic dextran corona. In vivo, they are recognized by the macrophages of the mononuclear phagocyte system. The amount of BSA bound to the particles, at adsorption equilibrium, has been determined through immunodiffusion, immunoelectrophoresis, and SANS. For particles with a radius of 25.3 nm, the adsorption was found to saturate at 64 adsorbed BSA molecules per particle. The configuration of the adsorbed BSA molecules was determined from the SANS scattering curves, first at full contrast, and then at contrast match. Both experiments indicate that the BSA molecules are adsorbed on the PICBA core, in a flat configuration. This result may be important for understanding the in vivo opsonization mechanisms of nanoparticles and their resulting biodistribution. 相似文献
92.
In the following article, we consider approximate Bayesian computation (ABC) inference. We introduce a method for numerically approximating ABC posteriors using the multilevel Monte Carlo (MLMC). A sequential Monte Carlo version of the approach is developed and it is shown under some assumptions that for a given level of mean square error, this method for ABC has a lower cost than i.i.d. sampling from the most accurate ABC approximation. Several numerical examples are given. 相似文献
93.
Anne‐Christine Schmidt Benjamin Fahlbusch Matthias Otto 《Journal of mass spectrometry : JMS》2009,44(6):898-910
Arsenic‐binding proteins are of toxicological importance since enzymatic activities can be blocked by arsenic interactions. In the present work, a novel methodology based on size exclusion chromatography coupled to electrospray ionization mass spectrometry (SEC‐ESI‐MS) was developed with special emphasis to preserve the intact proteins and their arsenic bindings. The eluent composition of 25 mM Tris/HCl, pH 7.5, with the addition of 100‐mM NaCl optimized for SEC with UV detection provided the highest SEC separation efficiency, but was not compatible with the ESI‐MS because of the non‐volatility of the buffer substance and of the salt additive. In order to find the best compromise between chromatographic separation and ionization of the arsenic‐binding proteins, buffer type and concentration, pH value, portion of organic solvent in the SEC eluent as well as the flow rate were varied. In the optimized procedure five different arsenic‐binding peptides and proteins (glutathione, oxytocin, aprotinin, α‐lactalbumin, thioredoxin) covering a molar mass range of 0.3–14 kDa could be analyzed using 75% 10‐mM ammonium formate, pH 5.0/25% acetonitrile (v : v) as eluent and a turbo ion spray source operated at 300 °C and 5.5 kV. A complete differentiation of all peptides and proteins involved in the arsenic‐binding studies as well as of their arsenic‐bound forms has become feasible by means of the extracted ion chromatograms (XIC) of the mass spectrometric detection. The new method offered the possibility to estimate equilibrium constants for the reaction of phenylarsine oxide with different thiol‐containing biomolecules by means of the XIC peak areas of reactants and products. Limits of detection in the range of 2–10 µM were obtained by SEC‐ESI‐MS for the individual proteins. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
94.
Shubhangi B. Umbarkar Trupti V. Kotbagi Ankush V. Biradar Renu Pasricha Jyoti Chanale Mohan K. Dongare Anne-Sophie Mamede Christine Lancelot Edmond Payen 《Journal of molecular catalysis. A, Chemical》2009,310(1-2):150-158
Acetalization of glycerol with various aldehydes has been carried out using mesoporous MoO3/SiO2 as a solid acid catalyst. A series of MoO3/SiO2 catalysts with varying MoO3 loadings (1–20 mol%) were prepared by sol–gel technique using ethyl silicate-40 and ammonium heptamolybdate as silica and molybdenum source respectively. The sol–gel derived samples were calcined at 500 °C and characterized using various physicochemical characterization techniques. The XRD of the calcined samples showed the formation of amorphous phase up to 10 mol% MoO3 loading and at higher loading of crystalline α-MoO3 on amorphous silica support. TEM analyses of the materials showed the uniform distribution of MoO3 nanoparticles on amorphous silica support. Raman spectroscopy showed the formation of silicomolybdic acid at low Mo loading and a mixture of α-MoO3 and polymolybdate species at high Mo loadings. Moreover the Raman spectra of intermediate loading samples also suggest the presence of β-MoO3. Acetalization of glycerol with benzaldehyde was carried out using series of MoO3/SiO2 catalysts with varying MoO3 loadings (1–20 mol%). Among the series, MoO3/SiO2 with 20 mol% MoO3 loadings was found to be the most active catalyst in acetalization under mild conditions. Maximum conversion of benzaldehyde (72%) was obtained in 8 h at 100 °C with 60% selectivity for the six-membered acetal using 20% MoO3/SiO2. Interestingly with substituted benzaldehydes under same reaction conditions the conversion of aldehydes decreased with increase in selectivity for six-membered acetals. These results indicate the potential of this catalyst for the acetalization of glycerol for an environmentally benign process. 相似文献
95.
96.
Bin Du Adam Langlois Daniel Fortin Christine Stern Pierre D. Harvey 《Journal of Cluster Science》2012,23(3):737-751
The title cluster is luminescent at 77?K and exhibits an unsaturated site for binding anions when the counter ion is PF6 ?. A series of five non-luminescent metalloporphyrins exhibiting carboxylate anchoring groups were synthesized and characterized. These are the sodium salts of the 5-carboxyphenyl-tri-10,15,20-tolyl-, trans-di-5,10-carboxyphenyl-di-15,20-tolyl-, and tetra-5,10,15,20-carboxyphenyl(metallo)porphyrin (metallo?=?chloroiron(III), nickel(II)) anions. Evidence for supramolecular assemblies between the carboxylates and the cluster is provided by 31P NMR and UV?Cvis spectroscopy. The binding constant, K1n, extracted from the UV?Cvis data via Benesi-Hildebrand, Scott and Scatchard plots are approximately 21,000?±?5,000?M?1 for the nickel(II) species, in agreement with the previously reported zinc(II) ones (K11?=?20,000?±?2,000?M?1), but those for the chloroiron(III) are measured to be lower (12,500?±?3,500?M?1). This association is accompanied by a complete quenching of the luminescence of the cluster which can only be due to an efficient energy transfer to the d?Cd states of the chloroiron(III) and nickel(II) species but an electron transfer from the nickel(II)-containing chromophore to the cluster is also possible. This work demonstrates the profound effect that supramolecular interactions may have on the photophysical properties despite the long donor?Cacceptor separation. 相似文献
97.
98.
99.
Erick Kindt Sandra Bak Mueller Christine Castle Carine M. Boustany‐Kari 《Biomedical chromatography : BMC》2010,24(7):752-758
Biomarkers are an increasingly important constituent of the drug development process, offering the potential of increased efficiency through reduced compound attrition and earlier proof of mechanism and/or efficacy. Assays developed for compound screening that can be directly translated for clinical trials are especially valuable, but their successful adoption requires a careful balance between assay performance and implementation costs. One such ‘fit‐for‐purpose’ biomarker assay, the indirect measurement of pharmacological modulation of sphingolipid biosynthesis and disposition, is presented here. Among spingolipids, numerous ceramide species are readily detectable in different lipoprotein fractions of mammalian plasma, but their parallel quantification can be prohibitively expensive and time consuming. Ceramides differ in their fatty acid moiety, which is readily removed by hydrolysis, yielding a common sphingosine derivative, the measurement of which serves as an indicator of total ceramide. When followed by liquid chromatography tandem mass spectrometry (LC/MS/MS) for detection, robust analyte quantification becomes relatively straightforward. The practical utility of a method developed to be fit for the purpose of rapidly and quantitatively measuring treatment‐induced variations in total ceramide from hamster plasma and individual lipoprotein fractions is described. With a linear calibration range from 0.003 to 33.4 μm sphingosine, precision and accuracy error in plasma‐based quality controls spiked with ceramides was less than 15%. The specificity of the assay for ceramides was also assessed. The simplicity of the method would allow for its potential translation to other preclinical species, as well as for clinical applications in later‐stage drug development. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
100.