Fluorometric investigation of the interaction of bovine serum albumin with surfactants and 6-mercaptopurine

Fluorescence quenching in solutions of bovine serum albumin has been investigated in the presence of 6-mercaptopurine and ionic surfactants. Spectroscopic analysis of the emission quenching at different temperatures revealed that the quenching mechanism of bovine serum albumin by 6-mercaptopurine was dynamic quenching mechanism. The Stern–Volmer quenching model has been successfully applied, and the activation energy of the interaction between 6-mercaptopurine and bovine serum albumin as much as 4.26 kJ mol⁻¹ was calculated. The distance r between donor (bovine serum albumin) and acceptor (6-mercaptopurine) was obtained according to fluorescence resonance energy transfer (FRET). The result of synchronous fluorescence spectra shows that the conformation of bovine serum albumin has been changed at the present of 6-mercaptopurine.     

Unusual volumetric and hydration behavior of the catanionic system sodium undecenoate: sodecyltrimethylammonium bromide

Following the studies on the effect of double bonds in the surfactant hydrophobic tail on the formation of mixed surfactant aggregates, we studied the viscosity and density of the system Sodium 10-undecenoate (SUD)–decyltrimethylammonium bromide (DTAB)–water. We found that the partial molar volume (pmv) and intrinsic viscosity of both, micellised and unmicellised mixtures, are non-ideal, dependent on the mixture composition and related to structural changes in micelles. These phenomena are caused by the presence of the double bond at the distal extreme of the SUD molecule, which has some affinity with water by formation of hydrogen bonds. In particular, as far as we know, this is the first report on non-ideal behavior of the pmv in mixed micelles.     

The aqueous cationic system sodium undecenoate-dodecyltrimethylammonium bromide at low concentration

The aqueous sodium undecenoate (SUD) –dodecyltrimethylammonium bromide (DTAB) catanionic system was studied at low concentration. The system did not precipitate, even at a 1:1 SUD:DTAB proportion, but showed the formation of a coacervate in a range of surfactant mixture compositions. Micelles have a preferential composition of 0.37 mole fraction of SUD. This behavior is attributed to the presence of the double bond at the distal extreme of the SUD molecule, which can form hydrogen bonds with water. Consequently, the –CH=CH₂ group is situated at the interface between the hydrocarbon micelle core and water, reducing the interfacial free energy. Structural computations demonstrate that the mentioned SUD proportion produces complete coverage of the micelle surface by the double bonds.     

Hydrogels in aqueous phases of polyvinylalcohol (PVA), surfactants and clay minerals

Aqueous solutions of synthetic clay minerals have been studied in the presence of surfactants and water-soluble polyvinylalcohol (PVA). The PVAs (PVA 1, PVA 2) had a molecular weight of about 10⁵ Dalton and a degree of hydrolysis of 82%. The PVA-samples were surface active and lowered the surface tension to 43 mN/m. As a consequence of their amphiphilic nature the PVA molecules bind strongly to clay mineral particles. On saturation the clay mineral particles adsorb the fivefold weight of PVA of their own weight. It is concluded that the thickness of the adsorbed layers on both sides of the clay mineral is in the range of the hydrodynamic diameter of the PVA-coils in the bulk phase.When the clay mineral particles are not saturated with PVA, they act as cross-linking agents for the PVA. The whole systems are physically cross-linked and assume gel-like properties. Rheological measurements show that samples behave like soft matter with a yield stress value. All of them have a frequency independent storage modulus which is an order of magnitude larger than the loss modulus. The hydrogels become stronger as PVA concentration increases.Small amounts of cationic surfactants bind on the clay mineral. The interface of the clay mineral becomes more hydrophobic and the binding of the PVA on the clay mineral is strengthened. With rising concentration of the surfactant the surfactant molecules bind on PVA and the PVA becomes hydrophilic. As a consequence the PVA can no longer bind on the clay mineral and the gels transform to viscous and turbid solutions. Small amounts of cationic surfactants therefore stiffen the hydrogels while larger amounts cause phase separation and a solution with low viscosity. Anionic surfactants like SDS do not bind on the clay mineral, but strongly on the PVA. With increasing SDS concentration, the hydrogels become stiffer at first but thereafter they break and transform to viscous fluids.In PVA-solutions without the clay minerals both cationic and anionic surfactants bind to the PVAs in the aqueous solution. With increasing concentration of surfactant, the viscosities of the solutions pass over a maximum. In this respect the PVAs behave like hydrophobically modified water soluble polymers. The surfactants bind to the hydrophobic microdomain and thereby crosslink the polymer molecules. On saturation the polyvinyl alcohol with anionic surfactant become hydrophilic and the network character disappears to a certain extent.     

盐类和温度对非离子型表面活性剂溶液粘度的影响

研究在各种盐类存在下,温度对非离子表面活性剂(OP类)溶液粘度的影响,发现相对粘度的对数值与1/T呈线性关系,从直线的斜率可得活化自由能ΔG′。由热力学关系式可计算粘性流体的活化焓ΔII′和活化熵ΔS′。用所得热力学函数对胶束型态的转化进行了讨论。     

Small angle X-ray scattering study of an extremely elongated micelle system of CTAB-p-toluidine solution

Whenp-toluidine is added to an aqueous solution of CTAB, a remarkable increase of viscosity is accompanied by a spectacular elasticity. We detected the existence of extremely elongated rod-like micelles in electron micrographs. SAXS measurements indicate a closely packed array of cylindrical rod-like micelles, brought about when solutions flow through a thin capillary. A scattering maximum ofd=160 Å almost corresponds to the distance between the nearest neighbours of the cylindrical rod-like micelles. This value agrees with the diameter measured on electron micrographs. The second broad peak (d=75 Å) is assigned to a subsidiary maximum of the shape function of the cylinder with infinite length.     

偶氮胂-DBS用于光度法测定牛血清白蛋白

在室温下,于pH 2.5的Britton-Robinson缓冲溶液中及非离子表面活性剂OP存在下,牛血清白蛋白(BSA)与偶氮胂-DBS的复合物的最大吸收在514 nm波长处,但显色复合物与试剂空白吸光度之差在370 nm处最大,选择在370 nm处测定,反应迅速完成。非离子表面活性剂OP可提高反应灵敏度及复合物稳定性。乙醇可提高体系灵敏度。BSA的质量范围在0~60.0 mg.L-1范围内符合比耳定律,方法表观摩尔吸光率3ε70 nm=8.58×105L.mol-1.cm-1。方法用于测定血清样品中蛋白质的总量,5次测定值的RSD为0.60%,回收率为98.0%。     

Aminolysis ofO-alkylO-4-nitropyenyl chloromethylphosphonates in reverse micellar solutions of the nonionic surfactant

The reaction ofn-hexylamine withO-alkylO-4-nitrophenyl chloromethylphosphonates in toluene solutions of poly(ethylene glycol)-600 monolaurate (PM) has been studied by spectrophotometry. The reverse micelles of the nonionic surfactant increase more than tenfold the observed rate constant of aminolysis. The catalytic activity of the surfactant is practically independent of the alkyl radical length of phosphonate. An increase in the concentration of amine results in a decrease in the catalytic efficiency. The character of the dependence of the rate constant on the concentration of PM is affected by the alkyl chain length of the substrate. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1735–1738, September, 1998.     

消除夹带溶胀的新液膜操作法

消除夹带溶胀的新液膜操作法曹汉瑾，褚莹，何彦涛，吴子生，严忠（东北师范大学化学系长春１３００２４）关键词液膜，油／水乳液，溶胀，夹带，包裹消除液膜操作中的夹带溶胀对液膜的工业化具有重要意义，夹带溶胀分为包裹溶胀和再液化溶胀。前者是乳状液滴上浮时将水相...     

羧甲基纤维素系列高分子表面活性剂超声合成的研究

研究了在超声波作用下羧甲基纤维素的降解反应及ＣＭＣ与具有不同亲水亲油比值的活性大单体「烷基醇（酚）聚氧乙烯醚丙烯酸酯及第三单体」的超声共聚反应。经萃取提纯的共聚产物用ＩＲ，＾１３Ｃ ＮＭＲ和ＵＶ等方法进行表证，证实通过超声反应制得了二元和三元共聚物。