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Milk and whey are widely processed by membrane filtration, often using polysulphone membranes. Adsorption of β-lactoglobulin onto polysulphone was studied at protein concn. of 0.1 and 1.0%, as well as 12% to represent concn. encountered during ultrafiltration. Adsorption onto silica and methylated silica surfaces (representing strongly hydrophilic and strongly hydrophobic surfaces resp.) was also
Polysulfone ultrafiltration membranes were modified with dextran, dextran sulfate and diethylaminoethyl (DEAE) dextran. The behavior of the modified membranes towards static adsorption of bovine serum albumin (BSA) was investigated in the pH range 3-7. The modified membranes showed lower flux losses after protein adsorption than unmodified membranes. The plain dextran was considered to be the best
The phenomenon of protein adsorption to solid surfaces affects the performance of many materials and processes, in areas ranging from medicine to biochemical engineering. Controlling protein adsorption, from solutions of single proteins as well as from more complex mixtures, requires an understanding of the mechanism(s) by which it occurs. This, in turn, entails detailed characterization of both t
The interaction of two ionic surfactants, CTAB and SDS, with β-lactoglobulin and lysozyme at surfaces was monitored by in situ ellipsometry. The effects of the surfactants on proteins adsorbed at a surface as well as the adsorption from protein/surfactant mixtures were studied. The behavior at four different surfaces, silicon oxide, chromium oxide, nickel oxide, and methylated silica, was investig
The captive bubble method was used to describe the wetting characteristics of a number of commercial ultrafiltration (UF) membranes. The membranes belonged to one of two homologous (same material, different cut-off) series made by the same manufacturer. One series was made of polysulphone and the other one of cellulose triacetate. The porosimetric characteristics of the membranes have also been me
The adsorption from a mixture of SDS and β-Lactoglobulin, 1:5 (), onto a methylated silica surface was studied in situ by ellipsometry. The amounts adsorbed from different concentrations of the mixture, at pH 7, were compared with those adsorbed from the corresponding pure SDS and β-lactoglobulin solutions. At high concentrations of the mixture, where the CMC of SDS is approached or exceeded, the The adsorption from a mixture of SDS and β-Lactoglobulin, 1:5 (), onto a methylated silica surface was studied in situ by ellipsometry. The amounts adsorbed from different concentrations of the mixture, at pH 7, were compared with those adsorbed from the corresponding pure SDS and β-lactoglobulin solutions. At high concentrations of the mixture, where the CMC of SDS is approached or exceeded, the
The elutability of adsorbed fibrinogen by cationic surfactants of different chain lengths (dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, cetyltrimethylammonium bromide), and an anionic surfactant (sodium dodecyl sulphate (SDS)) was studied using in situ ellipsometry. The concentrations of the surfactants were twice the CMC in water and for fibrinogen, 0.4 mg ml−1. The inve
The interaction between a cationic surfactant (dodecyltrimethylammonium bromide) and six model proteins adsorbed on to methylated silica and silica surfaces was investigated. The proteins were bovine serum albumin, cytochrome c, β-lactoglobulin, α-lactalbumin, lysozyme and ovalbumin. The adsorption of the proteins at pH 7 and their subsequent removal by surfactant were studied by in situ ellipsome
The change in the secondary structure of T4 lysozyme upon adsorption to silica particles was studied with circular dichroism. Two different mutants of the protein along with the wild type were investigated. The mutants differ from wild type by substitution of isoleucine for cysteine or tryptophan at position 3 and were chosen to represent a range of stability as quantified by their energies of the
Adsorption onto hydrophobic surfaces of α-, β-, γ-, and ω-gliadins from the wheat variety Chinese Spring was studied by means of in situ ellipsometry. Most measurements were conducted in 0·01m phosphate buffer, pH 6·0, with the protein concentrations 1, 5 and 25 μg/mL. The adsorbed amount varied between 1·3 and 11·4 mg/m2, which is high considering the low protein concentrations. The concentration
The adsorption of β-lactoglobulin to stainless steel and its subsequent removal were followed using in situ null ellipsometry. The influence of the surface pretreatment on the protein removal by the surfactant SDS and by sodium hydroxide was studied. All surfaces were precleaned in strongly alkaline solution. Some surfaces received no further pretreatment, while others were either passivated in ni
The adsorption of β-lactoglobulin to stainless steel and its subsequent alkali-induced removal were followed using ellipsometry. New steel samples differing in bulk composition, surface finish or chemical pretreatment were used. All surfaces were precleaned in strongly alkaline solution, and some were subsequently passivated in nitric acid. Furthermore, on surfaces differing in pretreatment measur
The adsorption of human carbonic anhydrase II pseudo-wild type (HCAIIpwt) and an N-terminally truncated version thereof onto silica surfaces were studied. The amount adsorbed and the adsorption kinetics were measured using in situ ellipsometry. A substantial difference was seen between the two proteins. The adsorbed amount of the truncated version (2.53 mg/m2) indicates an end-on orientation, whil
The effects of protein addition (lysozyme and bovine serum albumin) on surface tension reduction and cloud point of a surfactant (Pentaethyleneglycol Mono n-Dodecyl Ether (C12E5)) were studied. The minimum surface tension was in all cases 27 mN/m but was reached at a higher surfactant concentration for the BSA/ C12E5 solution than for the pure surfactant or the lysozyme/surfactant mixture, indicat
A description of general models for adsorption kinetics is given. Combinations of the models are compared with adsorption data for the self-associating proteins β-lactoglobulin A and B, from Elofssonet al.(U. M. Elofsson, M. A. Paulsson, and T. Arnebrant,Langmuir,submitted). The adsorption onto methylated silica surfaces was measured by these authors by ellipsometry in phosphate buffer (0.01M,pH 7
The adsorption and surfactant induced removal of T4 lysozyme was studied by in situ ellipsometry. Two proteins were investigated, wild type T4 lysozyme and a mutant protein where isoleucine 3 had been replaced by tryptophan (tryptophan mutant). The amount adsorbed is higher for the wild type protein than for the tryptophan mutant at the protein concentration employed (0.2 mg/mL). Furthermore, the
Ellipsometry and radio-labelling techniques were employed to study the deposition of human serum albumin (HSA) followed by excess of mono- or polyclonal anti-HSA to methylated silicon. Adsorbed HSA, and [HSA-monoclonal anti-HSA] layers were rapidly removed by 0.1-0.5% SDS, but [HSA-polyclonal anti-HSA] layers were not. The results suggest that antigens and polyclonal antibodies crosslink on surfac
The kinetics of the sequential adsorption of gliadins and water-soluble fraction (WSF) from the wheat variety Kosack onto hydrophobic silica (methylated silica) surfaces were studied by in situ ellipsometry. The measurements were made in water and in 0.01M acetate buffer, pH 4.0 and 5.0, with and without 0.1M NaCl. The concentration of gliadins and WSF was 1.7 µg/ml. The adsorption of gliadins in
In situ ellipsometry was used to study the adsorption/desorption of highly purified lipase from Humicola lanuginosa in mixtures with surfactants, at the solid/liquid interface. The effect of the surfactant was studied both when it was allowed to adsorb in mixture with lipase and when added after lipase adsorption. Silica surfaces, totally or partially methylated, were used and the surfactants wereIn situ ellipsometry was used to study the adsorption/desorption of highly purified lipase from Humicola lanuginosa in mixtures with surfactants, at the solid/liquid interface. The effect of the surfactant was studied both when it was allowed to adsorb in mixture with lipase and when added after lipase adsorption. Silica surfaces, totally or partially methylated, were used and the surfactants were
