Search results for "Colloid"
showing 10 items of 1288 documents
Supramolecular PEG-co-oligo(p-benzamide)s prepared on a peptide synthesizer.
2007
An automated synthesis protocol has been developed for the preparation of oligo(p-benzamide)s on solid support using a commercial peptide synthesizer employing a variation of standard Fmoc chemistry. Bis(trichloromethyl carbonate) in NMP was used to activate the aromatic carboxylic acids for acylation of secondary aromatic amines on solid support. N-Protected hepta(p-benzamide) was automatically prepared on solid support and manually converted to a solid supported block co-oligomer by attaching a poly(ethylene glycol) chain. Cleavage from the support could be achieved with minimal loss of the p-methoxybenzyl N-protective group. While the N-protected block co-oligomer was molecularly dissolv…
Alcoholic nanolime dispersion obtained by the insolubilisation-precipitation method and its application for the deacidification of ancient paper
2017
Abstract Nanolime dispersions for the deacidification of ancient paper constitute a valid alternative to the lime traditional ones. Their efficacy depends on particles size, polydispersity and agglomeration that can be controlled depending on the preparation method. In this work, nanolime preparation by insolubilisation-precipitation method is reported. Nanoparticles dispersed in a water-isopropanol mixture were obtained without any manipulation of the dispersion. The stability of the dispersion together with particle size and morphology were found to be dependent on water to isopropanol molar ratio and on the synthesis temperature. One of the dispersion was applied on a manuscript to asses…
Electrothermal Atomic Absorption Spectrometric Diagnosis of Familial Hypercholesterolemia
2000
We have developed a new nonradioactive assay to identify human low-density lipoprotein receptor defects. It is based on the incubation of cultured cells with colloidal gold-LDL conjugates and quantitation of the gold associated with the cells by electrothermal atomic absorption spectrometry. After an oxidative treatment with nitric and hydrochloric acids, the biological matrix interferes neither with the gold recovery nor with the gold measurements, which are linear, at least from 0.15 to 3 ng of gold. When cells expressing a functional LDL receptor are incubated with increasing amounts of colloidal-gold LDL conjugates, the obtained saturation curve parallels that described when [125I]LDL i…
Perspective: The Asakura Oosawa model: A colloid prototype for bulk and interfacial phase behavior
2014
In many colloidal suspensions, the micrometer-sized particles behave like hard spheres, but when non-adsorbing polymers are added to the solution a depletion attraction (of entropic origin) is created. Since 60 years the Asakura-Oosawa model, which simply describes the polymers as ideal soft spheres, is an archetypical description for the statistical thermodynamics of such systems, accounting for many features of real colloid-polymer mixtures very well. While the fugacity of the polymers (which controls their concentration in the solution) plays a role like inverse temperature, the size ratio of polymer versus colloid radii acts as a control parameter to modify the phase diagram: when this …
The solubilization site of 5,10,15,20-tetrakis-(2,6-dichlorophenyl)-porphyrin-Mn(III) in DPPC vesicles: A spectrophotometric and tensiometric study
2006
Abstract The solubilization site of 5,10,15,20-tetrakis-(2,6-dichlorophenyl)-porphyrin-Mn(III) (MnTDPPC) in l -α-dipalmitoylphosphatidyl choline (DPPC) vesicles was determined in a systematic UV–vis spectrophotometric study. Measurements of the MnTDPPC absorbance have been conducted at constant temperatures (in the interval 30 °C ≤ T ≤ 48 °C) and varying concentrations of phospholipid. In the entire temperature range, the absorption due to MnTDCCP was found to increase with increasing DPPC concentration, until it reaches a plateau value. The data have been analyzed using a pseudo-phase model yielding the binding constant of MnTDCPP to vesicular aggregates. No significant temperature depende…
Homochiral Metal-Organic Frameworks for Enantioselective Separations in Liquid Chromatography
2020
Selective separation of enantiomers is a substantial challenge for the pharmaceutical industry. Chromatography on chiral stationary phases is the standard method, but at a very high cost for industrial-scale purification due to the high cost of the chiral stationary phases. Typically, these materials are poorly robust, expensive to manufacture, and often too specific for a single desired substrate, lacking desirable versatility across different chiral analytes. Here, we disclose a porous, robust homochiral metal–organic framework (MOF), TAMOF-1, built from copper(II) and an affordable linker prepared from natural l-histidine. TAMOF-1 has shown to be able to separate a variety of model…
Silica Entrapment for Significantly Stabilized, Energy-Conducting Light-Harvesting Complex (LHCII)
2014
The major light-harvesting chlorophyll a/b complex (LHCII) of the photosynthetic apparatus in green plants consists of a membrane protein and numerous noncovalently bound pigments that make up about one-third of the molecular mass of the pigment-protein complex. Due to this high pigment density, LHCII is potentially interesting as a light-harvesting component in synthetic constructs. However, for such applications its stability needs to be significantly improved. In this work, LHCII was dramatically stabilized by enclosing it within polymerizing colloidal silica. The entrapped LHCII stayed functional at 50 °C for up to 24 h instead of a few minutes in detergent solution and clearly showed e…
Die Elimination von Hydroxyäthylstärke 200/0,5, Dextran 40 und Oxypolygelatine
1982
After withdrawal of 400 ml whole blood and subsequent infusion of 500 ml of a colloidal plasma substituent, the intravascular and renal colloid elimination was investigated in 40 test subjects. The individual colloidal solutions could no longer be demonstrated in the intravascular space after the following times: 10% hydroxyethyl starch 200/0.5 (anthrone method) after six weeks, 10% dextran 40 (anthrone method) after two weeks, 6% hydroxyethyl starch 200/0.5 (anthrone method) after four weeks and 5.5% oxypolygelatine (hydroxyproline method) after two days. Colloidal plasma substitutes are polydisperse solutions with various molecular weights and degree of hydroxyethylation and therefore, al…
Role of the co-surfactant nature in soybean w/o microemulsions.
2008
Abstract The influence of the co-surfactant on physicochemical properties of w/o soybean oil microemulsions (MEs) has been studied. In spite of the similarity in phase diagrams, the MEs display remarkable differences when examined by electrical conductivity, dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and linear voltammetry. When different short-chain alcohols were employed as co-surfactants, together with sodium dodecyl sulfate (SDS) as surfactant, the DLS results indicated the systems to be monodisperse. Both the electrical conductivity of the MEs and the hydrodynamic radii of the droplets (RH) increased with water content while RH diminished as temperature increas…
Structural and dynamical investigation of gelation containing water-in-oil microemulsions
1996
The gelatin (Bloom 300)/water/AOT/n-heptane system has been investigated at fixed water/AOT molar ratioR (R=31.1) as a function of the gelatin content. Several experimental techniques (densitometry, refractometry, conductometry, rheology, dielectrometry, ultrasonics, hypersonics) have been used to investigate the role played by the gelatin molecule in the observed sol-gel transition above a critical gelatin content. The results appear consistent with the hypothesis of a rigid network of gelatin-water rods coated by surfactant molecules coexisting with gelatin-free AOT reversed micelles at the gelation point.