双水相技术在抗生素分离中的应用

简单阐明了双水相技术在抗生素的分离中应用的发展状况,分析了影响双水相系统分离抗生素的各种因素,提出了导致双水相中抗生素非对称分配的主要作用力为疏不作用力,并对双水相技术在抗生素分离中应用的发展方向作了探讨。     

现代分离技术在抗生素提取中的应用*

详细介绍了膜分离技术在抗生素分离提取中的应用进展,并简单阐明了高效毛细管电泳技术、双水相技术和反胶束萃取技术在抗生素提取中的应用情况。对这些现代分离技术的发展前景作了简要探讨。     

现代分离技术在抗生素提取中的应用

详细介绍了膜分离技术在抗生素分离提取中的应用进展,并简单阐明了高效毛细管电泳技术、双水相技术和反胶束萃取技术在抗生素提取中的应用情况。对这些现代分离技术的发展前景作了简要探讨。     

双水相技术在酶分离纯化中的运用

阐述了双水相技术在酶分离纯化中的应用 ,分析了影响双水相技术分离纯化酶的各种因素 ,并探讨了双水相技术在酶分离纯化应用中的发展方向     

离子液体双水相体系及其在生物分离中的应用

作为一种高效而温和的新型绿色分离体系,离子液体双水相体系结合了离子液体和双水相体系的优点。因此倍受国内外研究者的青睐。介绍了双水相萃取技术的原理和离子液体双水相体系;综述了离子液体双水相体系在生物分离中的研究进展,主要包括抗生素、蛋白质、和食用色素等的萃取分离;并展望了离子液体双水相体系在生物分离中的应用前景。     

微生物胞内产物分离的新方法—双水相萃取技术

本文简要地介绍了双水相萃取技术的概念,综述了双水相取技术的特点及其在内产物分离中的应用,讨论了影响细胞碎片的去除和双水相萃取效果的参数,以及成相材料的回收利用等问题,展示了双水相萃取技术的新发展。     

双水相体系逆流色谱技术在蛋白质分离中的应用

双水相体系逆流色谱技术结合了逆流色谱的高效率、高制备量以及双水相体系适于蛋白质分离的特点,因此在蛋白质的分离方面具有独特的应用价值。本文综述了近年来基于正交轴逆流色谱仪器的双水相体系逆流色谱技术在多种蛋白质分离中的应用。并对一些新兴的蛋白质逆流色谱分离技术及新型逆流色谱柱分离系统进行了介绍。     

双水相萃取技术在白藜芦醇提纯工艺中的应用

论文研究了双水相萃取体系在提纯白藜芦醇工艺中的应用,用乙醇-硫酸胺-水双水相体系使虎杖提取液中的各物质按极性不同在油水两相中得到分离。双水相萃取时,白藜芦醇的含量远高于有机溶剂萃取,达34.29%。可见双水相技术可以完全代替有机溶剂萃取技术提纯白藜芦醇,产品纯度高,具有工艺简单,毒性小,成本低等优点。     

双水相萃取技术新进展

本文简要介绍了双水相萃取技术在生物活性物质的纯化及分析上的应用,并且从四个方面总结了双水相萃取技术的新进展和发展方向。     

天然植物多糖分离纯化技术研究现状和进展

植物多糖因具有抗肿瘤、增强免疫、抗氧化等功效而备受关注,多糖的分离纯化是多糖结构和生物活性研究的首要前提。本文系统介绍了传统的水提醇沉法以及酶提取法、超声波辅助提取法、超临界流体萃取法、超高压提取技术微波辅助提取法和双水相萃取等新技术,对其分离原理、处理方式和效果进行分析比较和综述;从物理分离方式、分子间作用力及化学性质分离的角度,综述植物粗多糖分离和纯化方法及途径,为天然植物中多糖的分离纯化和综合利用提供参考。     

Development of a general ligand for immunoaffinity partitioning in two phase aqueous polymer systems

The effect on the partition of erythrocytes in a two phase aqueous polymer system based on dextran T500 and polyethylene glycol (PEG) 8000 of a combination of immunoaffinity ligands, namely, rabbit immunoglobulin G (IgG) and PEG 1900-modified monoclonal IgG, was examined as a potential cell separation technique. Several hybridoma lines secreting mouse monoclonal IgG specific for the Fc receptor of rabbit IgG were raised. The monoclonal IgG was modified by cyanuric chloride attachment of PEG 1900, causing the modified antibody to partition predominantly into the PEG-rich upper phase of the systems. The PEG-modified monoclonal IgG was used as an affinity ligand in the two phase polymer system to specifically increase the partition of rabbit anti-NN glycophorin IgG. The rabbit IgG was applied together with the PEG-modified monoclonal IgG to increase the partition of human erythrocytes. The same system had no effect on the partition of rabbit erythrocytes. These experiments demonstrate that a monoclonal antibody can be modified and used as a general reagent with which to alter cell partition in two phase aqueous polymer systems in an immunologically specific manner.     

Partitioning of pristinamycins in aqueous two-phase systems: A first step toward the development of antibiotic production by extractive fermentation

The partitioning of pristinamycins was studied in dextran and polyethylene glycol (PEG) aqueous two-phases systems. Pristinamycins partitioned preferentially into the PEG-rich top phase. The partition coefficient was independent of molar mass of PEG and dextran and of antibiotic concentration, but, increased exponentially with the tieline length of the system. Partition of pristinamycins was greatly improved when fatty acids esters of PEG were mixed with PEG. In such mixtures, the partition of coefficient increased up to a value of 24, dependent on the carbon chain length of fatty acids and the modified PEG concentrations. Moreover, in such system, the two groups of pristinamycins, I and II, were extracted in accordance with their hydrophobicity. Recovery of pristinanamycins produced by Streptomyces pritinaespiralis in a fermentation broth was achieved with a dextran/PEG system. Cells were confined into the bottom phase and pristinamycins partitioned in the top phase. However, due to binding of the pristinamycins to the cells, the partition coefficient was slightly lower than of pure antibiotics solutions. (c) 1994 John Wiley & Sons, Inc.     

Determination of lipid loss during aqueous and phase partition fixation using formalin and glutaraldehyde

Phase partition fixation permits fixation of tissue in a nonaqueous environment, thus eliminating osmotic effects. It was shown in an earlier investigation that retention of protein in liver blocks can be improved by phase partition fixation. By using radioisotopic labeling techniques, the effects of phase partition fixation on lipid retention during fixation, dehydration, and clearing have been determined and compared with those of standard aqueous fixation techniques. In this article we show that retention of total lipid in liver blocks following phase partition fixation using formalin was comparable to or better than that with aqueous formalin fixation and processing. Fixation with glutaraldehyde using phase partition fixation resulted in somewhat greater loss of total lipid than that observed for aqueous buffered glutaraldehyde-fixed blocks.     

Optimization of bovine serum albumin partition coefficient in aqueous two-phase systems

Partitioning of proteins in aqueous two-phase systems has been shown to provide a powerful method for separating and purifying mixtures of biomolecules by extraction. These systems are composed of aqueous solutions of either two water-soluble polymers, usually polyethylene glycol (PEG) and dextran (Dx), or a polymer and a salt, usually PEG and phosphate or sulfate. There are many factors which influence the partition coefficient K, the ratio of biomolecule concentration in the top phase to that in the bottom phase, in aqueous two-phase systems. The value of the partition coefficient relies on the physico-chemical properties of the target biomolecule and other molecules and their interactions with those of the chosen system. In this work, the partition behavior of pure bovine serum albumin in aqueous two-phase systems was investigated in order to see the effects of changes in phase properties on the partition coefficient K. The concentration of NaCl and pH were considered to be the factors having influence on K. Optimal conditions of these factors were obtained using the Box-Wilson experimental design. The optimum value of K was found as 0.0126 when NaCl concentration and pH were 0.14 M and 9.8, respectively, for a phase system composed of 8% (w/w) polyethylene glycol 3,350 - 9 (% w/w) dextran 37,500 - 0.05 M phosphate at 20 °C.     

Systematic Approach to Solvent Selection for Biphasic Systems with a Combination of COSMO‐RS and a Dynamic Modeling Tool

Biphasic aqueous‐organic systems are important reaction systems for catalytic processes. This is especially true for biocatalysis where the range of accessible products can be significantly extended. In such systems, the aqueous phase is the reactive phase in which the biocatalyst is dissolved and the organic phase is nonreactive and acts as substrate reservoir and as in situ product extraction solvent. Here, the choice of the nonreactive phase is highly important for the overall performance of the system. In this contribution, a systematic approach to solvent selection for biphasic aqueous‐organic systems is presented with respect to partition coefficients. The model reaction is the stereoselective carbon‐carbon coupling of two 3,5‐dimethoxy‐benzaldehyde molecules to (R)‐3,3',5,5'‐tetramethoxy‐benzoin catalyzed by benzaldehyde lyase (EC 4.1.2.38) from Pseudomonas fluorescens. A systematic approach to solvent selection consisting of two steps is proposed: Firstly, the conductor‐like screening model for real solvents (COSMO‐RS) is used to facilitate a fast solvent screening. Since this is an ab initio approach it allows a pre‐screening without laborious experimental input. The proposed ranking of solvents, based on the ratio of partition coefficients at infinite dilution, is a sound basis for the successive steps. Secondly, a dynamic model is fitted to experimental data in order to obtain detailed and reliable results for mass transfer and partition coefficients. Therefore, the method makes efficient use of the experimental data and substantiates quantitative results with guided experiments.     

Aqueous two-phase polymer partitioning of lipid vesicles of defined size and composition

The kinetics of the partitioning of lipid vesicles containing acidic phospholipids in aqueous two-phase polymer systems are dependent upon the vesicle size; the larger the vesicles, the more readily they absorb to the interfaces between the two polymer phases and hence are cleared from the top phase as phase separation proceeds. The partitioning of neutral lipid vesicles is principally to the bulk interface and is the same in phase systems of both low and high electrostatic potential difference between the two phases (delta psi). The incorporation of negatively charged lipids has two effects upon partition. First, vesicles with negatively charged lipids exhibit increased bottom phase partitioning in phases of low delta psi due to an enhanced wetting of the charged lipids by the lower phase. Second, the presence of a negatively charged group on the vesicle surface results in increased partition to the interface and top phase in phase systems of high delta psi. Differences observed in the partition of vesicles containing various species of negatively charged lipid thus reflect a competition between these two opposing factors.     

Interaction of amphiphilic substrates (acyl-CoAs) and their metabolites (free fatty acids) with microsomes from mouse sciatic nerves

We have measured the partition of stearoyl-CoA and oleoyl-CoA between an aqueous phase and the microsomes from mouse sciatic nerves. A method of microultracentrifugation was used which allowed us to study separately the aqueous phase and the biological membranes. We observed that the partition is dependent upon the amount of acyl-CoAs and membrane proteins but seems to be independent of time. A theoretical analysis of these data allowed interpretation of the binding and release in terms of acyl-CoA surface density in the vesicles. We have also analyzed the fate of the membrane-bound acyl-CoAs. We show that, whereas the apparent partition does not seem to vary, the hydrolysis of the membrane-bound acyl-CoAs followed by the release of free fatty acids from the membrane leads to a modification of the partition of acyl-CoAs between the membrane and the aqueous phase. We propose that there is a constant partition of the aliphatic chains (acyl-CoAs + free fatty acids).     

Behavior in two-phase aqueous polymer systems of L5178Y mouse leukemic cells : II. The lag and exponential phases of growth

The behavior of lag and exponential growth phase L5178Y mouse leukemic cells under normal and prolonged lag phase conditions with respect to partition in aqueous dextran — polyethylene glycol polymer systems has been studied. ‘Backculture’ of early stationary cells into fresh growth medium is accompanied by a decrease in partition ratio from 0.52 to 0.11. The partition ratio remains depressed for a time considerably longer than the duration of lag phase but rises rapidly and returns to its former value as the cells reach late exponential/early stationary phase. If lag phase is prolonged, the time for which the partition ratio remains depressed is also prolonged. In the exponential phase following a prolonged lag phase, the partition ratio rises at a rate slower than during a normal exponential phase and does not reach the same magnitude for the same position in the cycle. Net negative surface charge as measured by particle microelectrophoresis does not change appreciably throughout the growth cycle. The results suggest that the sequence of events at the cell surface on a populational basis which contribute to the partitioning behavior is possibly predetermined or programmed at the time of transfer into fresh medium. The results further substantiate the technique of aqueous polymer partitioning as being the most sensitive method available for monitoring subtle changes in plasma membrane properties during the cell growth cycle.     

Separation and determination of tetracycline hydrochloride in real water samples using binary small molecule alcohol‐salt aqueous two‐phase system coupled with high‐performance liquid chromatography

An environmental and sensitive sample pretreatment method was established and combined with high‐performance liquid chromatography (HPLC) for the analysis of tetracycline hydrochloride (TC) in feed water and lake water. One element small molecule alcohol‐salt aqueous two‐phase system (ATPS) cannot effectively adjust the polarity of the system, but binary small molecule alcohol‐salt ATPS can adjust the polarity and improve the extraction efficiency of antibiotics. In this work, a binary ATPS based on ethanol +2‐propanol + (NH₄)₂SO₄ system was formed and applied to the separation and purification of TC in real water samples. The influence factors on partition behaviors of TC were discussed, including the types and the concentration of phase salts, the volume ratio of alcohol, the pH value, extraction temperature, and the standing time. The response surface methodology was used to determine the best experimental conditions for multi‐factor experiments. Under this optimal condition, the extraction efficiency of TC reached 95.7%. This new method is considered to have significant application in the divorce of antibiotics.     

Determination of partition coefficient by the change of main phase transition

The molar partition coefficients of amphiphilic additives, e.g. local anesthetics, between the aqueous phase, the liquid crystal and the gel phase of lipid membrane can be determined based on a combination of phase transition data obtained at high and low concentrations of the lipid in aqueous phase. The data obtained at high lipid concentration allow to find the phase diagram lipid-additive in the aqueous environment. The combination of this diagram with data obtained at low lipid and additive concentrations provides direct information on the concentration of anesthetics in the lipid and thus allows the calculation of the partition coefficient.