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61.
Helmuth Galster 《Fresenius' Journal of Analytical Chemistry》1988,330(4-5):297
Ohne Zusammenfassung
Electrometric determination of the hygiene auxiliary parameters pH-value and redox voltage相似文献
62.
Donath E Moya S Neu B Sukhorukov GB Georgieva R Voigt A Bäumler H Kiesewetter H Möhwald H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(23):5481-5485
Three-dimensional ultrathin polymer shells have been produced by a combination of step-by-step adsorption of polyelectrolytes on glutaraldehyde-treated human erythrocytes and subsequent solubilization of the cytoplasmatic constituents by means of a deproteinizing agent. The obtained hollow films preserve both the size and shape of the templating cells. This opens a pathway for the fabrication of polymeric capsules within a wide range of size and shape by using various biological templates. They may have exciting potential applications, such as templates for nanocomposites, as containers for a large class of materials, or as cages for chemical reactions. The thickness of the films can be adjusted over a large range: from a few nm up to several tens of nm. The polymer shells are permeable to small molecules and ions but not to macromolecules. An increase in the ionic strength of the solution up to 100 mmol make the capsules permeable for proteins. Permeability and conductivity studies have provided evidence that the adsorption of lipids on polyelectrolyte layers is a means of producing capsules with controlled permeability properties. 6-Carboxyfluorescein and Rhodamin 6G were precipitated within the capsules. 相似文献
63.
Fandiño AS Rais I Vollmer M Elgass H Schägger H Karas M 《Journal of mass spectrometry : JMS》2005,40(9):1223-1231
The application of two-dimensional electrophoresis for the identification of hydrophobic membrane proteins is principally hampered by precipitation of many of these proteins during first-dimension, isoelectric focusing. Therefore new strategies towards the identification and characterization of membrane proteins are being developed. In this work we present a direct and rapid approach from blue-native gels to mass spectrometry, which allows the analyses of complete complexes and prevents protein aggregation of hydrophobic regions during electrophoresis. We combine blue-native gel electrophoresis and liquid chromatography--nanospray-iontrap tandem mass spectrometry to analyze the composition of oxidative phosphorylation complexes I, III, IV and V from bovine-heart mitochondria as a model system containing a number of highly hydrophobic proteins. Bands from blue-native gels were subjected either to in-gel or to in-solution tryptic digestion. The obtained peptide mixtures were further analyzed by liquid chromatography--tandem mass spectrometry and the corresponding proteins were identified by database search. From a total of 86 proteins, 67 protein subunits could be identified including all highly hydrophobic components, except the ND4L and ND6 subunits of complex I. We demonstrate that liquid chromatography--tandem mass spectrometry combined to blue-native electrophoresis is a straightforward tool for proteomic analysis of multiprotein complexes, and especially for the identification of very hydrophobic membrane protein constituents that are not accessible by common isoelectric focusing/sodium dodecyl sulphate gel electrophoresis. 相似文献
64.
Novel capsules with high stability and controlled permeability by hierarchic templating 总被引:5,自引:0,他引:5
Dai Z Dähne L Möhwald H Tiersch B 《Angewandte Chemie (International ed. in English)》2002,41(21):4019-4022
65.
Moura Edmilson M. Terra Vilma R. Siebald Helmuth G. L. de Lima Geraldo M. Paim Lilian A. Dias Fabrícia M. 《Transition Metal Chemistry》2003,28(4):437-442
A series of heterobimetallic complexes containing Ru–Sn bonds, of general formula [RuCp(L)2SnX2Y] [L = PPh3, 1/2 dppe = 1,2-bis(diphenylphosphino)ethane; X, Y = F, Cl and Br], was prepared and studied by elemental analysis, 119Sn-Mössbauer spectroscopy, i.r. and 1H-, 13C-, 19F-, 31P- and 119Sn-n.m.r. spectroscopy. 119Sn-Mössbauer studies allowed determination of the coordination number of the SnII center as well as the group electronegativity of the organometallic fragment [RuCp(L)2]+. These results, supported by multinuclear n.m.r. data suggested that the electronic charge distribution between the RuII and SnII centers are strongly dependant upon the nature of L and the electronegativity of X and Y. 相似文献
66.
Human serum albumin (HSA) and L-alpha-dimyristoylphosphatidic acid (DMPA) were applied as a pair to encapsulate ibuprofen microcrystals by means of a technique based on the layer-by-layer (LbL) assembly of oppositely charged species, for the purpose of controlling drug release. The successful adsorption of HSA and DMPA multilayers onto ibuprofen crystals was confirmed by optical microscopy. The drug release process, in a solution of pH 7.4, was monitored by optical microscopy and UV spectroscopy. The results revealed that the rate of release of ibuprofen from HSA/DMPA microcapsules decreased as the capsule wall thickness and drug crystal size increased, indicating that the permeability of the microcapsules can be controlled by simply varying the number of HSA/DMPA deposition cycles. 相似文献
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70.
Petrov JG Andreeva TD Möhwald H 《Langmuir : the ACS journal of surfaces and colloids》2006,22(9):4136-4143
A comparison of the collapse of Langmuir monolayers of docosyl trifluoroethyl ether (DFEE) and docosyl ethyl ether (DEE) on water shows that in both films the 3D phase is formed layer-by-layer. The substitution of CH3 by a CF3 group in the hydrophilic head yields a more stable bilayer exhibiting lower equilibrium spreading pressure, pi(esp)(DFEE) < pi(esp)(DEE). Upon lateral compression, the DFEE bilayer fractures abruptly as a compact solid body whereas the DEE bilayer breaks down gradually as a polycrystalline material. A comparison of the collapse kinetics of the two films at the same constant supersaturation pi-pi(esp) = 7 mN/m shows that the fluorinated DFEE monolayer transforms more quickly, yielding a stable bilayer of closely packed upright molecules, whereas the DEE film undergoes a continuous monolayer-bilayer-multilayer transition. Brewster angle microscopy allows us to visualize different collapse mechanisms of the DFEE and DEE films; the domains of the fluorinated DFEE bilayer grow laterally at constant thickness and density, and the collapse of the nonfluorinated DEE monolayer occurs through a sequence of disordered stripelike and broken elongated textures. The characteristic molecular areas of the monolayer and bilayer collapse suggest that the 2D-3D transition in the DFEE and DEE films is accompanied by at least partial dehydration of their headgroups. The faster collapse of the fluorinated monolayer could result from a lower energy barrier due to the more hydrophobic CF3 group in the heads. The increased stability of the DFEE bilayer could be associated with the electrostatic attraction between the -C(F delta-)3 versus (H delta+)3C- terminals at the heads-to-tails contact plane of the top and the bottom layer, contrasting with the repulsion between the -C(H delta+)3 versus (H delta+)3C- terminals of the top-layer heads and the bottom-layer tails in the DEE bilayer. 相似文献