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641.
Hamideh Salehi Isabelle Calas‐Bennasar Jean‐Cdric Durand Elodie Middendorp Jean Valcarcel Christian Larroque Katalin Nagy Kinga Turz K Imre Dekany Frdric J. G. Cuisinier 《Journal of Raman spectroscopy : JRS》2014,45(9):807-813
Confocal Raman microscopy, a noninvasive, label‐free, and high‐spatial resolution imaging technique, in combination with K‐mean cluster analysis and a correlation coefficient map, was employed to trace titanium dioxide (TiO2) nanoparticles in living MCF‐7 and TERT cells. The penetration of TiO2 nanoparticles into cells revealed a gradual time‐dependent diffusion of nanoparticles over the entire cell. Cell apoptosis was monitored by tracing cytochrome c diffusion into the cytoplasm. A comparison with the mitochondrial clustering indicated that cytochrome c was inside the mitochondria for TiO2 concentration of 2 µg ml−1. This result demonstrates that the presence of TiO2 particles within a cell does not induce apoptosis. We demonstrated that confocal Raman microscopy allow to follow penetration of TiO2 particles in cell and to monitor the apoptotic status of the penetrated cells. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
642.
643.
Vachon J Harthong S Jeanneau E Aronica C Vanthuyne N Roussel C Dutasta JP 《Organic & biomolecular chemistry》2011,9(14):5086-5091
Inherently chiral phosphonatocavitands with various bridging moieties at their wide rim were synthesized. Optical resolution by chiral HPLC was performed with cavitand 8 to afford enantiopure compounds (+)-8 and (-)-8. The molecular structures of hosts 8 and 12 were determined by X-ray diffraction. The host properties were investigated by (1)H and (31)P NMR spectroscopy. The phosphonatocavitands form inclusion complexes with chiral ammonium neurotransmitters, some presenting enantioselectivity towards the right or left-handed host enantiomers. 相似文献
644.
645.
Yannick Tauran Moez Rhimi Ryohei Ueno Marie Grosso Arnaud Brioude Erwann Janneau Kinga Suwinska Rima Kassab Patrick Shahgaldian Alessandro Cumbo Bernard Fenet Beomjoon Kim Anthony W. Coleman 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):213-221
The molecular recognition by para-sulphonato-calix[4]arene of cytosine, occurs in solution, in the solid-state and by assembly on the surface of para-sulphonato-calix[4]arene capped silver nanoparticles. Each of these states shows different modes of assembly; in solution a 1:1 complex is formed; in the solid state a 4:1 assembly exists, however some of the cytosine molecules are present as space fillers and do not participate in the host (guest complexes, finally on the surface of the hybrid silver/para-sulphonato-calix[4]arene nanoparticles a 2:1 cytosine/para-sulphonato-calix[4]arene assembly is observed. The assembly processes have been studied by DOSY NMR, fluorescence spectroscopy, Dynamic Light Scattering (DLS), Single Crystal Solid State Diffraction, Visible Spectroscopy and Electron Microscopy. The results demonstrate how cytosine initiates the aggregation of the hybrid silver/para-sulphonato-calix[4]arene hybrid nanoparticles. 相似文献
646.
Edward J. Hsieh Michael S. Bereman Stanley Durand Gary A. Valaskovic Michael J. MacCoss 《Journal of the American Society for Mass Spectrometry》2013,24(1):148-153
Reversed-phase liquid chromatography is the most commonly used separation method for shotgun proteomics. Nanoflow chromatography has emerged as the preferred chromatography method for its increased sensitivity and separation. Despite its common use, there are a wide range of parameters and conditions used across research groups. These parameters have an effect on the quality of the chromatographic separation, which is critical to maximizing the number of peptide identifications and minimizing ion suppression. Here we examined the relationship between column lengths, gradient lengths, peptide identifications, and peptide peak capacity. We found that while longer column and gradient lengths generally increase peptide identifications, the degree of improvement is dependent on both parameters and is diminished at longer column and gradients. Peak capacity, in comparison, showed a more linear increase with column and gradient lengths. We discuss the discrepancy between these two results and some of the considerations that should be taken into account when deciding on the chromatographic conditions for a proteomics experiment. Figure
The effects of column and gradient lengths on the performance of nanoflow LC-MS/MS is examined in complex proteomic samples. 相似文献
647.
Globular proteins are an important component of many food products. Heat-induced aggregation of globular proteins gives them new properties that can be useful in food products. In order to optimize functionality, the aggregation process needs to be controlled, which in turn requires good understanding of the mechanism. Heating aqueous solutions of globular proteins leads to the formation of aggregates with one of four distinctly different morphologies: spherical particles, flexible strands, semi-flexible fibrils, and fractal clusters. We review recent research in this area focusing on the parameters that control the morphology including the influence of hydrolysis. The aggregation mechanism and the effect of the morphology on the functionality will be addressed. A distinction is made between primary aggregation leading to roughly spherical particles or more or less flexible strands and secondary aggregation leading to fractal clusters, gels or precipitates. We will discuss how the formation of aggregates with different morphologies is related to the formation of either particulate or fine stranded gels. 相似文献
648.
Durand N Mariot D Améduri B Boutevin B Ganachaud F 《Langmuir : the ACS journal of surfaces and colloids》2011,27(7):4057-4067
The modification of silica nanoparticles with hexafluoropropylene oxide (HFPO) oligomers has been investigated. HFPO oligomers with two different average degrees of polymerization (DPn = 8 and 15) were first prepared by anionic ring-opening polymerization, deactivated by methanol, and in some cases postfunctionalized by aminopropyl(tri)ethoxysilane or allylamine. The "grafting onto" reactions of these oligomers were then carried out either on bare silica (reaction between a silanol surface and ethoxy-silanized HFPO) or on silica functionalized by amino groups (in an amidation reaction with methyl ester-ended HFPO) or mercapto groups (via the radical addition of allyl-functionalized HFPO). Hybrid nanoparticles thus obtained were characterized by solid-state (29)Si NMR and FTIR spectroscopies as well as elemental and thermogravimetric analyses. The results assessed a significant yield of covalent grafting of HFPO oligomers when performing the hydrolysis-condensation of ethoxylated HFPO on the bare silica surface, compared to the other two methods that merely led to physically adsorbed HFPO chains. Chemically grafted nanohybrids showed a high thermal stability (up to 400 °C) as well as a very low surface tension (typically 5 mN/m) compared to physisorbed complexes. 相似文献
649.
The remarkable conservation of protein structure, compared to that of sequences, suggests that, in the course of evolution,
residue substitutions which tend to destabilise a particular structure must be compensated by other substitutions that confer
greater stability on that structure. Given the compactness of proteins, spatially close residues are expected to undergo the
compensatory process. Surprisingly, approaches designed to detect such correlated changes have led, until now, only to limited
success in detecting pairs of residues adjacent in the three-dimensional structures. We have undertaken, by simulating the
evolution of DNA sequences including sites mutating in a correlated manner, to analyse whether such poor results can be attributed
to the detection methods or if this failure could result from a compensatory process more complex than that implicitly underlying
the different approaches. Present results show that only methods taking into account the phylogenetic reconstruction can lead
to correct detection.
Received: 24 April 1998 / Accepted: 8 August 1998 / Published online: 11 November 1998 相似文献
650.
V. Lesturgeon D. Durand T. Nicolai 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,9(1):83-91
Free radical co-polymerization of methyl methacrylate (MMA) and ethyl glycol dimethyl methacrylate (EGDMA) in solution leads
to the formation of polydisperse branched PMMA which grows in size until the system gels. The structure and the size distribution
of the PMMA aggregates were characterized at infinite dilution using static and dynamic light scattering and size exclusion
chromatography (SEC). The reaction extent was measured using SEC and Raman spectroscopy. The results show that the structure
and size distribution of PMMA aggregates formed close to the gel point are compatible with those of percolating clusters.
The structure factor of semi-dilute solutions of PMMA aggregates is the same as that of dilute solutions at distance scales
much smaller than the correlation length of the concentration fluctuations (). However, the cut-off function of the pair correlation function at for semi-dilute solutions is more gradual than the cut-off function at for dilute solutions.
Received 11 May 1998 and Received in final form 22 October 1998 相似文献