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111.
Vincent Martinez Prof. Dr. Maged Henary 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(39):13764-13782
Nile red and Nile blue are highly fluorescent and photostable organic dyes from the benzo[a]phenoxazine family. They have been used as histological stains for imaging lysosomes and lipids in vitro. The dyes’ high quantum yields and solvent‐dependent optical properties make them ideal scaffolds for the development of pH probes and local polarity indicators. Reviews of the literature in this area are scarce with only one review ever published in 2006. It has been 10 years since and the field has evolved. This review aims to expand upon topics covered by the previous reviewers and to report on recent advances in the literature. As authors, we hope to convey a sense of scope and to spark renewed interest in this useful niche of dye chemistry. 相似文献
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114.
Malcher M Volodkin D Heurtault B André P Schaaf P Möhwald H Voegel JC Sokolowski A Ball V Boulmedais F Frisch B 《Langmuir : the ACS journal of surfaces and colloids》2008,24(18):10209-10215
A new antibacterial coating made of poly(L-lysine)/hyaluronic acid (PLL/HA) multilayer films and liposome aggregates loaded with silver ions was designed. Liposomes filled with an AgNO 3 solution were first aggregated by the addition of PLL in solution. The obtained micrometer-sized aggregates were then deposited on a PLL/HA multilayer film, playing the role of a spacer with the support. Finally, HA/PLL/HA capping layers were deposited on top of the architecture to form a composite AgNO 3 coating. Release of encapsulated AgNO 3 from this composite coating was followed and triggered upon temperature increase over the transition temperature of vesicles, found to be equal to 34 degrees C. After determination of the minimal inhibitory concentration (MIC) of AgNO 3 in solution, the antibacterial activity of the AgNO 3 coating was investigated against Escherichia coli. A 4-log reduction in the number of viable E. coli cells was observed after contact for 120 min with a 120 ng/cm (2) AgNO 3 coating. In comparison, no bactericidal activity was found for PLL/HA films previously dipped in an AgNO 3 solution and for PLL/HA films with liposome aggregates containing no AgNO 3 solution. The strong bactericidal effect could be linked to the diffusion of silver ions out of the AgNO 3 coating, leading to an important bactericidal concentration close to the membrane of the bacteria. A simple method to prepare antibacterial coatings loaded with a high and controlled amount of AgNO 3 is therefore proposed. This procedure is far superior to that soaking AgNO 3 or Ag nanoparticles into a coating. In principle, other small bactericidal chemicals like antibiotics could be encapsulated by this method. This study opens a new route to modify surfaces with small solutes that are not permeating phospholipid membranes below the phase transition temperature. 相似文献
115.
M. Granet A. Nonell G. Favre F. Chartier H. Isnard J. Moureau C. Caussignac B. Tran 《Spectrochimica Acta Part B: Atomic Spectroscopy》2008
In the general frameworks of the nuclear fuel cycle and environmental research field, the Cs isotopic composition must be known with high precision and accuracy. The direct determination of Cs isotopes by mass spectrometry techniques is generally hampered by the presence of Ba isobaric interferences however. Here we present a new method which takes advantage of the collision-reaction cell based Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) and allows to analyse Cs isotopes in the presence of Ba without prior separation step. The addition of N2O gas in the cell leads to an antagonistic behavior of Cs+ and Ba+ as the latter reacts with the gas to form BaO+ and BaOH+ products whereas Cs+ remains unreactive. The efficiency of the method was demonstrated for an UOx sample by comparing the results obtained (1) from the measurements of pure Cs fractions and (2) from Fission Products fractions containing more than 30 ionisable elements in addition to Cs, Ba, and where U and Pu were previously removed by using ion exchange resin. An excellent agreement is achieved between each set of experiments with an external reproducibility always better than 0.5% (RSD, k = 2). This study confirms the strong potential of collision–reaction cell to measure Cs isotopes in presence of interfering Ba, precluding therefore former systematic chemical separations. 相似文献
116.
von Holst C Baeten V Boix A Slowikowski B Fernández Pierna JA Tirendi S Dardenne P 《Analytical and bioanalytical chemistry》2008,392(1-2):313-317
Near-infrared microscopy (NIRM) has been proved to be a powerful tool for the detection of banned meat and bone meal (MBM) in feed. The identification of MBM traces and its ability to differentiate animal from vegetable feed ingredients is based on the evaluation of near-infrared spectra obtained from individual particles present in the sample. This evaluation is supported by appropriate decision rules for the absorbances at specific wavelengths. Here we show that the method and the corresponding decision rules can be successfully transferred from the laboratory which constructed the decision rules to two independent laboratories that were not involved in the calibration process of the method. The analytical results from blind feed samples containing MBM (positive samples) and feed samples without MBM (negative samples) revealed a very good agreement between the three laboratories, thus demonstrating the transferability of the method. 相似文献
117.
Srivastava S Ball V Podsiadlo P Lee J Ho P Kotov NA 《Journal of the American Chemical Society》2008,130(12):3748-3749
The exponentially growing layer-by-layer (LBL) films made from poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) were used to load and unload the CdTe nanoparticles (NPs). The reversible loading of NPs were investigated through UV-vis studies and further confirmed by confocal microscopy. In addition the LBL films were also compared for the release kinetics for pH 9 and 7 and films capped with (PDDA-PSS)10 layers. The amount of released particles at pH 9 was found to be at least 2 orders of magnitude higher than those at pH 7 and with (PDDA-PSS)10 capped layers after 25 h. This variation in film response for CdTe-particle release presents a route for studies in which highly swollen exponentially growing LBL films can be loaded with functionalized NPs for biological applications and explored as carriers to hold the NPs inside the films for self-assembly. 相似文献
118.
Human skin is repeatedly exposed to UVR that influences the function and survival of many cell types and is regarded as the main causative factor in the induction of skin cancer. It has been traditionally believed that skin pigmentation is the most important photoprotective factor, as melanin, besides functioning as a broadband UV absorbent, has antioxidant and radical scavenging properties. Besides, many epidemiological studies have shown a lower incidence for skin cancer in individuals with darker skin compared to those with fair skin. Skin pigmentation is of great cultural and cosmetic importance, yet the role of melanin in photoprotection is still controversial. This article outlines the major acute and chronic effects of UVR on human skin, the properties of melanin, the regulation of pigmentation and its effect on skin cancer prevention. 相似文献
119.
Timmons SC Hui JP Pearson JL Peltier P Daniellou R Nugier-Chauvin C Soo EC Syvitski RT Ferrières V Jakeman DL 《Organic letters》2008,10(2):161-163
A bacterial alpha-d-glucopyranosyl-1-phosphate thymidylyltransferase was found to couple four hexofuranosyl-1-phosphates, as well as a pentofuranosyl-1-phosphate, with deoxythymidine 5'-triphosphate, providing access to furanosyl nucleotides. The enzymatic reaction mixtures were analyzed by electrospray ionization mass spectrometry and NMR spectroscopy to determine the anomeric stereochemistry of furanosyl nucleotide products. This is the first demonstration of a nucleotidylyltransferase discriminating between diastereomeric mixtures of sugar-1-phosphates to produce stereopure, biologically relevant furanosyl nucleotides. 相似文献
120.
Anaïs Geny Dr. Nicolas Agenet Dr. Laura Iannazzo Max Malacria Prof. Dr. Corinne Aubert Dr. Vincent Gandon Dr. 《Angewandte Chemie (International ed. in English)》2009,48(10):1810-1813
Cobalt cyclopentadienyl complexes incorporating a fumarate and a CO ligand (see picture) efficiently catalyze inter‐ and intramolecular [2+2+2] cycloadditions of alkynes, nitriles, and/or alkenes to give benzenes, pyridines, or 1,3‐cyclohexadienes. Unlike catalysts such as [CpCo(CO)2] or [CpCo(C2H4)2] (Cp=C5H5), they are air‐stable, easy to handle, compatible with microwave conditions, and do not necessarily require irradiation to be active.