表面活性剂在逆胶束酶反应系统中的作用机制

随着胶体界面科学与酶技术的发展,逆胶束酶反应系统作为酶等生物分子的高效分离或催化转化的介质体系,为分子生物技术的发展带来了新的机遇.表面活性剂分子特有的两亲性结构,能使微水相以纳米尺寸的水滴形式稳定在非极性有机溶剂中,为酶的活性保持提供了典型的类生物膜微环境.本文对逆胶束酶反应系统原理做简要介绍,并解析表面活性剂的浓度变化及其构型差异在逆胶束酶反应系统中的作用机制,综述近年来表面活性剂在逆胶束酶领域应用的最新成果,同时探讨了新型功能性表面活性剂在胶束酶学中的应用前景和研究趋势.     

新型阴离子表面活性剂的合成及其反胶束体系的酶催化性能

合成了未见文献报道的新型阴离子表面活性剂磷酸二[(2-乙基己氧基)乙基]酯钠(sodium di-[(2-ethylhexyloxy)ethyl] phosphate,DEEPA);以核磁共振氢谱和红外光谱表征了它的结构;在DEEPK/异辛烷反胶束体系中进行了脂肪酶催化橄榄油水解反应实验.结果表明,该反胶束体系的催化活性优于AOT反胶束体系,更优于油-水双相中的酶催化反应,最大活性是油-水双相体系的1.86倍.     

Surfactant effect on enhancing (S)-naproxen prodrug production from racemic naproxen by lipase

In the enantioselective esterification of racemic naproxen with 4(2-hydroxyethyl) morpholine by Lipase MY in organic solvents, a productivity improvement of the desired (S)-naproxen ester from 0.42 to 0.72 mM at the reaction time of 130 h was observed, when the surfactantbis (2-ethylhexyl) sodium sulfosuccinate (AOT) was added in the reaction mixture. The presence of a small amount of exogenously added water dramatically activated the enzyme in AOT/cyclohexane-reversed micelles. Desorption of the surfactant molecule from the enzyme mass and solubilization of the enzyme into reversed micelles were used to elucidate an existing maximum of the initial rate of (S)-naproxen synthesis with the water content. Moreover, the effects of alcohol and surfactant concentration on the enzyme activity are reported.     

碳氟表面活性剂与水成膜泡沫灭火剂

本文从碳氟表面活性剂与水成膜泡沫灭火剂的关系出发，分析了我国水成膜泡沫灭火剂未能大量推广使用的主要原因。对发展我国自己的碳氟表面活性剂工业，以促进水成膜泡沫灭火剂的进一步发展提出了看法。     

Simultaneous quantification of poly-dispersed anionic, amphoteric and nonionic surfactants in simulated wastewater samples using C18 high-performance liquid chromatography-quadrupole ion-trap mass spectrometry

This paper describes the development of a guantitative method for direct and simultaneous determination of three frequently encountered surfactants, amphoteric (cocoamphoacetate, CAA), anionic (sodium laureth sulfate, SLES), and nonionic (alcohol ethoxylate, AE) using a reversed-phase C18 HPLC coupled with an ESI ion-trap mass spectrometer (MS). Chemical composition, ionization characteristics and fragmentation pathways of the surfactants are presented. Positive ESI was effective for all three surfactants in agueous methanol buffered with ammonium acetate. The method enables rapid determinations in small sample volumes containing inorganic salts (up to 3.5 g L(-1)) and multiple classes of surfactants with high specificity by applying surfactant specific tandem mass spectrometric strategies. It has dynamic linear ranges of 2-60, 1.5-40, 0.8-56 mg L(-1) with R2 egual or greater than 0.999, 0.98 and 0.999 (10 microL injection) for CAA, SLES, and AE, respectively.     

AEOT反胶束中脂肪酶的催化活性

反胶束已广泛应用于膜模拟化学和蛋白质的液 液萃取中[1～ 3] ,反胶束酶反应作为实现有机相酶催化的方法之一 ,具有许多独特的优点 ,反胶束独特的结构特征使表面活性剂分子组成的膜将油水相隔开 ,从而有利于保持酶的活性和稳定性。酶在反胶束的微水环境中比在水溶液中更接近天然的细胞内环境 ,在这里酶和底物分子均可得到有效的分散 ,接触几率大大提高 ,因而催化效率也得到很大提高。反胶束可以适用于各种类型的 (亲水的、疏水的和双亲的 )底物[4] ,已逐步形成“胶束酶学”的研究分支 ,研究胶束酶学的Martinek等[3] 曾预言 :反胶束体系有可…     

Simultaneous separation of nine surfactants of various types by HPLC with evaporative light scattering detection

A simultaneous separation of cationic, amphoteric and nonioinc nine surfactants (DMDS, DMDP, DMDM, DMDL, BZC, CDE, A/O, SUNC, IMD) has been performed by a reverse phase-HPLC method utilizing a single J'sphere ODS (250 mm × 4.6 mm, 4 μm) column and a methanol-water containing 0.2% TFA eluent system within 60 min. The observed precision in determination of concentration was less than 5% R.S.D., which revealed that ELSD was an effective tool to detect the various studied surfactants of low volatility without chromophore. In addition, the detection limits were in the concentration range of 3.5-10 μg/mL, and the calibration curves, i.e. the log-log plots, were linear in the working range of 5-4600 μg/mL with the slopes of 1.321-1.668. The application of the analytical procedure to three household products without pretreatment supported that the presented chromatographic method was simple to be practical for a routine analysis of commercial products.     

季铵盐表面活性剂引起非水混合溶剂的分相

当季铵盐表面活性剂在极性溶剂中具有合适溶解度时, 它可使该极性溶剂与另一种非极性溶剂形成的混合溶剂自发分相, 形成稳定的两相界面. 借鉴表面活性剂双水相现象的概念, 这种现象被称为表面活性剂非水双相(NSTP), 也可简称为双油相. 产生此种现象的原因被归结为季铵盐表面活性剂在极性溶剂中达到合适的溶解度时, 从而逐出与之不亲合的非极性溶剂.     

Synthesis and Characterization of Zirconia Nanocrystallites by Cationic Surfactant and Anionic Surfactant

1 INTRODUCTION Zirconia is a kind of metallic oxide with high mel- ting point. It is highly corrosion-resistant for acid fu- sant and neutral fusant, thus it can be used as refrac- tory material, and it can also be utilized as acid acy- loxy bi-functional catalystic material owing to hav- ing both acid and alkali surface centers[1]. Moreover, zirconia has superior ion-exchange capacity as well as chemical and mechanical stability, therefore, it can also be applied as a catalyst carrier. …     

Fluorous synthesis of mono-dispersed poly(ethylene glycols)

Mono-dispersed poly(ethylene glycols) (PEGs) are of great value in the development of biopharmaceuticals. However, tedious synthesis limits the availability of mono-dispersed PEGs. To address this issue, a fluorous synthesis of mono-dispersed PEGs, discretely PEGylated surfactants and ¹⁹F magnetic resonance imaging (MRI) agents has been developed. During the synthesis, both fluorous and normal phase silica gel-based solid-phase extractions were successfully employed to simplify the purifications. This synthesis provided an easy access to valuable mono-dispersed PEGs and related molecules for biomedical application on multi-gram scales.     

反胶团相转移法提取牛血清白蛋白

介绍了在利用CTAB／正辛醇：三氯甲烷(4：1V／V)反胶团体系对牛血清白蛋白(BSA)进行相转移中,通过对萃取体系水相的pH值、离子强度、两液相的体积比、小分子糖(葡萄糖、蔗糖)及助表面活性剂(直链醇分子)等因素的改变,探讨了BSA在阳离子表面活性剂体系的萃取机理;研究结果表明选择合适的条件提取BSA时,萃取率可达到97％,反萃率达到了85％;找到实现牛血清白蛋白分离提纯的有效方法。     

Calorimetric investigation of the formation of ZnS nanoparticles in w/o microemulsions

The enthalpies of precipitation of ZnS nanoparticles within water containing reversed micelles of sodium bis(2-ethylhexyl) solfosuccinate, L-α phosphatidylcholine, tetraethyleneglycol-mono-n-dodecyl ether and didodecyldimethylammonium bromide as a function of the molar concentration ratioR (R=[water]/[surfactant]) were measured by calorimetric technique. The results indicate that the energetic state of ZnS nanoparticles confined in the aqueous core of the reversed micelles is different from that in bulk water. Effects due to nanoparticle size, adsorption of HS⁻ ions on the nanoparticle surface and interactions between nanoparticles and water/surfactant interfaces are discussed. This work has been supported by MURST.     

Dielectric relaxation measurements on aerosol-OT/water/cyclohexane-solutions at low water content

The complex relative dieletric permittivity of aerosol-OT(AOT)/water/cyclohexane solutions has been measured within the frequency range 5 kHz-10 GHz. The investigated solutions were of oil-rich type with varying AOT- and water content. A marked dielectric relaxation has been found. The dielectric increment as well as the conductivity steeply increase with the water content, while the relaxation time decreases. Theoretical models of heterogeneous dielectrics consisting of polar, highly conductive inclusions in a nonpolar solvent with low conductivity have been applied to the results, allowing conclusions with regard to the inclusions, shape and conductivity.     

The Determination of Polycyclic Aromatic Hydrocarbons in Indigenous and Transplanted Mussels (Mytilys Edulis L.) Along the Dutch Coast

Abstract

A method, originally developed to investigate the pollution of Dutch coastal water with metals and PCBs,¹ was modified for the determination of the pollution with polycyclic aromatic hydrocarbons (PAH).

The method is based on active biological monitoring with mussels (Mytilus edulis L.). Its usefulness has already been demonstrated.² In the present study a method for the determination of PAH in mussels has been developed. The method is based on the hydrolysis of tissue with 4 M sodium hydroxide, extraction with hexane, clean-up with 10% deactivated aluminium oxide and quantitative determination with Reversed Phase High Performance Liquid Chromatography (RP-HPLC) and fluorescence detection.

The accumulation plateau of most of the PAH studied has not been reached after 60 days. Gradients of pollution were found, and at least one significant source near IJmuiden was detected.     

Current perspective of sustainable surfactants based on renewable building blocks

Surfactants are active or essential ingredient of several industrial and consumer formulations. These amphiphilic organic molecules demonstrate unique ability to adsorb at the interface and self-aggregate or self-assemble into different phases in aqueous or nonaqueous solution. In recent years, environmental concerns coupled with increased consumer awareness have guided substantial growth of environmentally benign surfactant molecules often termed as ‘green surfactants’, oleochemical-based surfactants', ‘renewable surfactants’ ‘biosurfactants’, ‘natural surfactants’, and so on. These groups of new generation of eco-friendly surfactant molecules often directly or indirectly derived/developed from renewable building blocks can be broadly termed as ‘sustainable surfactants’ which are increasingly becoming popular in many application areas. The ever-increasing demand of surfactants in several application areas necessitates development of many new structural analogs of these molecules by sustainable approach. This review summarizes recent progress in the area of sustainable surfactants, their potential impact, and future perspective.     

A comparative study on the cooperative binding of surfactants with solubilized polymers and networks

The cooperative binding of a linear as well as a crosslinked polyelectrolyte with an oppositely charged surfactant has been analyzed theoretically and experimentally. The experimental results showed that the presence of crosslinkage significantly enhances the initiation process but strongly suppresses the cooperation of the binding. In the theoretical analysis, the hydrophobic interaction has been treated using the nearest-neighbor interaction model, while the electrostatic interaction has been calculated using a rodlike model. The general formulas derived on the basis of the free energy minimum principle demonstrated that the crosslinkage enhances the initiation process but strongly suppresses the cooperation owing to the osmotic pressure in the network domain. The theoretical results showed fairly good agreement with the experimental data, confirming the essential features of the theory.     

Rheological Properties of Wormlike Micelles Formed by Cetyltrimethylammonium Bromide and Sodium Laurate

Aqueous solutions of mixed cationic and anionic surfactants, cetyltrimethylammonium bromide (CTAB) and sodium laurate (SL), have been studied by steady-state rheology and dynamic oscillatory technique. Wormlike micelles can form due to attractive interactions between the oppositely charged headgroups of CTAB and SL. The wormlike micelles formed by CTAB/SL have been compared with that of cetylpyridinium bromide (CPB)/SL by steady-state rheology method. Effects of additional components such as NaBr, 1-propanol, 1-butanol, polyvinylpyrrolidone (PVP) on the micelles formation process have also been investigated. Cole-Cole plot has been applied to study the dynamic viscoelasticity of the wormlike micelles.     

Polymer/surfactant interactions at the air/water interface

The development of neutron reflectometry has transformed the study and understanding of polymer/surfactant mixtures at the air/water interface. A critical assessment of the results from this technique is made by comparing them with the information available from other techniques used to investigate adsorption at this interface. In the last few years, detailed information about the structure and composition of adsorbed layers has been obtained for a wide range of polymer/surfactant mixtures, including neutral polymers and synthetic and naturally occurring polyelectrolytes, with single surfactants or mixtures of surfactants. The use of neutron reflectometry together with surface tensiometry, has allowed the surface behaviour of these mixtures to be related directly to the bulk phase behaviour. We review the broad range of systems that have been studied, from neutral polymers with ionic surfactants to oppositely charged polyelectrolyte/ionic surfactant mixtures. A particular emphasis is placed upon the rich pattern of adsorption behaviour that is seen in oppositely charged polyelectrolyte/surfactant mixtures, much of which had not been reported previously. The strong surface interactions resulting from the electrostatic attractions in these systems have a very pronounced effect on both the surface tension behaviour and on adsorbed layers consisting of polymer/surfactant complexes, often giving rise to significant surface ordering.     

Further Investigation into the Stability of Water-in-Crude Oil Emulsions Formed in Burgan Oilfield: Effect of Toluene,Resins to Asphaltenes Ratio,and Surfactant

Factors controlling the formation and stabilization of water-in-crude oil (w/o) emulsions in oil fields are of great concern to the petroleum industry for the economic development of underground oil reservoirs. Controlling and minimizing the formation of w/o emulsions and demulsification of water from emulsions are also important for environmental development. Because of its importance, the mechanisms, formation, and stability of w/o emulsions have received considerable attention. This article deals with some of the factors responsible for the formation and stabilization of w/o emulsions formed in Burgan oil field in Kuwait. Some of the factors investigated in this study are the naturally occurred surface active components of crude oils such as asphaltenes and resins. Stability of emulsion samples with resins to asphaltenes ratio (R/A) contents of 3, 5, 9, 12, and 20 has been studied. It was found that Emulsion tightness is correlated with resins to asphaltene content of the sample. As the R/content increases the emulsion becomes unstable. The effect of additives such as toluene and dodecyle benzene sulfonic acid (DBSA) on the stability of various emulsion samples collected from oil field are also reported. A 2 wt% of DBSA was found to resolve all the water from emulsion samples collected from Burgan oilfield.     

非传统晶体生长的早期观察

晶体早期生长的研究揭示,在某些体系中,晶体生长可能并不遵循传统路径.借由某些聚合物或生物分子的帮助,无机晶体的前驱体或纳米晶体在生长初期有可能聚集为无序的大块颗粒.这些聚集体表面晶化形成高结晶度高密度的外壳,随后完成从表面到核心的晶化过程.此逆向晶体生长机理在一些诸如沸石、钙钛矿、金属和金属氧化物等无机化合物体系中均已被发现,在其他材料体系里也将得到验证.认识这一新的晶体生长路径将给予我们更多的自由度来实现晶体形态控制,也有助于我们对于许多天然矿物形成机制的理解.本文简要回顾了最近本领域研究中一些典型逆向晶体生长的例子.