动态光散射分析不同物化条件下酪蛋白的聚集行为及其胶束尺寸

采用动态光散射技术考察了酪蛋白胶束在各种物化条件(温度、浓度、pH、离子强度、乙醇)下的聚集行为,并测定了胶束尺寸。结果表明:热处理导致酪蛋白胶束发生离解,平均流体力学半径(Rh)值不断减小,且当蛋白浓度较低时热离解过程为可逆,而浓度较高时则为不可逆;酪蛋白胶束的Rh值随蛋白浓度及离子强度的增加均呈现先减小后逐渐增大的趋势,并分别在2g/L和0.1mol/L时达到最小值;而Rh值随pH值的增加则先增大再逐渐减小,并在pH7.0时达到最大值;添加乙醇使酪蛋白胶束不断聚集,Rh值逐渐增加,溶液散射光强(Iθ)呈指数增长。     

激光光散射研究天花粉蛋白的聚集过程

运用激光光散射技术研究天花粉蛋白在水溶液及不同浓度KSCN水溶液中的聚集过程．KSCN的加入能提高天花粉在水溶液中的稳定性. KSCN浓度大于0．5mol•L－1时，天花粉溶液透明、稳定，溶液中天花粉以单个分子与聚集体两种形式存在．聚集体主要是由约120个天花粉分子组成，平均流体力学半径Rh值约为49nm，在溶液中排列疏松，类似θ溶剂中的无规线团。     

Laser Light Scattering Study on Aggregation of Cellulose Diacetate in Acetone

We have investigated the properties of cellulose diacetate in solution by using laser light scattering. The cellulose diacetate molecules can form micelles and micellar clusters in acetone besides the individual chains. As the concentration increases, the average hydrodynamic radius （Rh） linearly increases, whereas the ratio of gyration radius to hydrodynamic radins 〈Rg〉/〈Rh〉 linearly decreases. It indicates that the micelles associate and form micellar clusters due to the intermolecular interactions.     

Interaction between phospholipid vesicular structures with long chain zwitterionic surfactants

Solubilization of different zwitterionic phospholipid vesicles structures such as L--phosphatidylcholine (PC) and 1,2-didecanoyl-sn-glycero-3-phosphocholine (DPC) have been studied in aqueous bulk by using zwitterionic surfactant dimethylhexadecylammoniopropanesulfonate (HPS). This has been done by studying the aggregation of HPS in pure water and in the presence of 7–36 M of fixed concentrations of each lipid with the help of pyrene fluorescence intensity (I ₁/I ₃) measurements. The fluorescence measurements showed that HPS monomers undergo two kinds of aggregation process, which were identified by the three breaks in a plot of pyrene fluorescence versus HPS concentration. The first two breaks, C ₁ and C ₂, indicate the onset and completion of vesicle solubilization respectively, upon incorporation of HPS monomers into the vesicles and led to solubilization in the form of mixed micelles. This process was not clearly visible at low lipid concentration. We evaluated the partition coefficient (K), which defines the degree of partitioning of surfactant monomers into the vesicles with respect to the aqueous medium. A high K value of HPS-lipid aggregates indicates the stronger interactions between surfactant and lipid vesicles. The K values evaluated for PC and DPC are quite close to each other, which indicates that K values were independent of phospholipid chain length.     

凝胶化反应中标度行为及凝胶化点关系

在苯乙烯(St)-二乙烯苯(DVB)自由基聚合的凝胶化反应过程中,定时取样,得到凝胶化点前后及直至反应终点的一系列溶胶样品,利用光散射技术研究了溶胶相的重均分子量M_w、尺寸均方旋转半径R_g的变化过程,建立了M_w、R_g和反应时间t的标度关系,并在此基础上提出一神新的准确求取凝胶化时间t_gel的方法.     

光散射技术在高分子表征研究中的应用

光散射技术是高分子领域中重要的表征手段之一.静态光散射和动态光散射的结合能够获得丰富的关于高分子的信息,如重均分子量、回转半径、第二维里系数、流体力学半径、尺寸分布、分子链构象等.除合成高分子外,光散射技术同样适用于研究生物大分子、微生物、胶体、纳米粒子、病毒、囊泡等在溶液或悬浮液中的行为.本综述重点介绍稀溶液中静态光...     

Mixed micellization of anionic–nonionic surfactants in aqueous media: a physicochemical study with theoretical consideration

Mixed micellization of binary and ternary mixtures of anionic and nonionic surfactants, such as lithium dodecyl sulfate, polyoxyethylene(23)laurylether, and polyoxyethylene-tert-octylphenylether, is studied in aqueous solution using tensiometric, conductometric, and spectrophotometric methods. Although tensiometry and conductometry complement each other closely, the spectroscopic critical micellar concentration (cmc) is far from agreement with tensiometric study. Several parameters, e.g., cmc, degree of counterion binding, free energies of micellization, and interfacial adsorption, have been evaluated. Established theories of Clint, Rosen, Rubingh, Motomura, Georgiev, Maeda, and Blankschtein were applied to evaluate the mole fraction of different components in the self-aggregated phase, the interaction parameter, free energy contributions, and expected cmc.     

Polycaprolactone-b-Poly(ethylene oxide) Biocompatible Micelles as Drug Delivery Nanocarriers: Dynamic Light Scattering and Fluorescence Experiments

Summary: Dynamic light scattering (DLS) and fluorescence experiments were carried out to study PCL₄₄-b-PEO₁₁₄ biocompatible micelles used as nanocarriers in drug delivery. Micelles prepared by a simple procedure (THF removal under nitrogen flow) exhibited a narrow size distribution with an average diameter of 100 nm. For micelles containing a hydrophobic model compound (pyrene) within the PCL core, a smaller average micellar size of 80 nm was observed, with a simultaneous broadening in the size distribution profile. In parallel to DLS results, fluorescence experiments showed evidence of pyrene encapsulation, and that the onset of the micellization process occurs at approximately 10/90 (v/v) THF/water mixtures in the case of PCL₄₄-b-PEO₁₁₄ polymer.     

Formation of Vesicles and Micelles in Aqueous Systems of Tetrameric Acids as Determined by Dynamic Light Scattering

A comprehensive dynamic light scattering (DLS) study on the system BP10Na₄/water is presented. BP 10Na₄ is a tetrameric fatty acid in sodium form. In order to change molecular packing conditions both electrolyte (NaCl) and alcohol (1-butanol, 1-pentanol) are added to the surfactant system. Phase diagrams of the systems reveal not only an extensive micellization, but also the occurrence of a lamellar liquid crystalline D phase. The DLS study shows an existence of vesicles at very dilute BP10Na₄ concentrations ( ?cmc) and also a co-existence of micelles and vesicles at higher BP10Na₄ concentrations. Cryo-TEM pictures verify the existence of the vesicles. Based on the DLS and SLS experiments the weight-average molar mass of the micelles are estimated to be 13500 g/mol at 100 mM NaCl and 22700 g/mol at 600 mM. The corresponding aggregation numbers are 13 and 22, respectively.     

时间分辨激光光散射测量系统

自选设计，装配了一套时间分辨的激光光散射测量系统，该系统摄像机，录像机，计算机和自编的软件实现了一体化的数据采集，显示和分析过程，本文给出了该系统的应用实例，球晶的光散射和环氧树脂的固化反应诱导的相分离过程。     

Determination of Nucleic Acid Using the Resonance Light Scattering Technique with the Mixed Complex La(phen)(o-phthalic acid)

A mixed complex of lanthanum with o-phenanthroline (phen) and o-phthalic acid (C₈H₆O₄) was synthesized. The resonance light scattering (RLS) and UV characteristics of interaction between La(phen)(C₈H₆O₄) and ctDNA were studied. Based on the enhancement of RLS intensity of La(phen) (C₈H₆O₄) by DNA at 400nm in the pH range of 6.5 to 7.5, a new method for determination of nucleic acids has been developed. The calibration curve was linear in the range of 0.023 to 1.87µgmL^–1. The detection limit (3) was 0.023µgmL^–1. Interference by coexisting substances in the determination of DNA was also examined. Three synthetic samples were determined with satisfaction.     

Light Scattering Experiments on Shear Induced Structures of Micellar Solutions

The formation of shear induced structures (SIS) of a mixed micellar solution of tetradecyldimethylaminoxide and sodium dodecylsulfate is studied by light scattering experiments under shear (rheo-optical method). In the shear rate- as well as in the time-dependent measurements we found an aggregation process taking part in the SIS formation. Below the critical shear rate for the occurrence of SIS, the shear rate dependent experiments show an increased scattering intensity, indicating micellar associates. Above the critical shear rate, we found structures oriented in the direction of flow. The time dependent measurements show that the SIS formation can be regarded as a process which can be divided into three stages: induction—aggregation—orientation. After the aggregation, we found a temporal process in which the orientation increases to reach complete orientation in the direction of flow.     

混合反胶束的电导与微结构研究

反胶束是两亲分子在非极性溶剂中形成的一种有序组合体，在医药、化工、采油、胶束催化及酶催化等领域中有重要应用．与胶束溶液相比，人们对反胶束的形成与结构的了解至今仍不充分．特别是对于由混合表面活性剂形成的反胶束的研究几乎无人涉及．本文采用动态光散射、电导及荧光光谱等手段对阴离子表面活性剂AOT与非离子表面活性剂形成的混合反胶束进行了研究，旨在探讨利用表面活性剂的复配来调节和控制反胶束的结构和性能．亚实验部分二异辛基磺化琉璃酸钠（AOT，Sigma公司）；Brij30为含4个氧乙烯基（EO基）的十二碳醇（AcrosOrgani…     

Solution Crystallization Analysis by Laser Light Scattering (SCALLS)

Summary: Solution crystallization analysis by laser light scattering offers a direct way of studying the solution crystallization of polyolefins. The technique yields similar results to Crystaf, but in a shorter time and with apparently greater sensitivity in some cases. The use of SCALLS is demonstrated for the study of selected propylene/higher α-olefin copolymers. Some conclusions are also drawn regarding the effect of molecular weight on the solution crystallization of polyolefins.     

Hydrodynamic Radius Characterization of a Vinyl-Type Polynorbornene by Size-Exclusion Chromatography with a Static and Dynamic Laser Light Scattering Detector

Both absolute molecular weight and molecular sizes (radius of gyration and hydrodynamic radius) of a vinyl-type polynorbornene eluting from size-exclusion chromatography columns were determined by combined with a static and dynamic laser light scattering detector. The hydrodynamic radius of polymer fraction eluting from size-exclusion chromatography columns was obtained from dynamic laser light scattering measurements at only a single angle of 90° by introducing a correction factor. According to the scaling relationship between molecular sizes and molecular weight and the ratio between radius of gyration and hydrodynamic radius, the vinyl-type polynorbornene took a random coil conformation in 1,2,4-trichlorobenzene at 150 °C.     

动态光散射法研究季铵盐Gemini表面活性剂的胶团化行为

用动态光散射技术在10～70℃温度范围内,通过测定胶团的平均流体力学半径随温度、盐浓度和联接基团长度的变化情况,研究联接基团为聚亚甲基链的阳离子季铵盐Gemini表面活性剂胶团在无机盐介质中的长大规律.实验结果表明,增加盐量、降低温度和减小联接基团的长度均使平均流体力学半径变大,Gemini表面活性剂胶团长大时是由球状转变为棒状.从实验测定的平流体力学半径求算了支配球-棒转变的平衡常数及热力学函数值,并用NNLS(non-negatively constrainedleast square)算法对胶团的粒径分布情况进行了分析.此外,对具有短联接基团的Gemini表面活性剂胶团长大所具有的独特性质进行了讨论.     

Use of a Dynamic Light Scattering Technique for SDS/Water/Pentanol Studies

The interpretation of micelle/aggregate size obtained by use of the DLS technique for SDS/water/pentanol systems was discussed by comparison of the results of measurement with theoretical data. For most of the studied systems, the apparent radii (R _h,app ) did not satisfactorily characterize the size of the aggregates (R _h,app  < 1 nm). The use of a correction factor (f = 0.26) confirmed that the discrepancies were associated with the electrostatic intermicellar interactions. However, the fuzzy optical interface between dispersed and dispersing phases can also be the reason of such results. An increase of pentanol content caused a decrease of the droplet radius in w/o systems but in o/w systems the changes were negligible.     

混合胶束中Gemini阳离子表面活性剂14-s-14与常规表面活性剂的协同作用:连接臂及反离子效应(英文)

The mixed micelle formation of binary cationic 14-s-14 gemini with conventional single chain surfactants was studied by conductivity measurements.The critical micelle concentration(cmc) and the degree of counterion binding values(g) of the binary systems were determined.The results were analyzed by applying regular solution theory(RST) to calculate micellar compositions(X),activity coefficients(f1,f2),and the interaction parameters(β).The synergistic interactions of all the investigated cationic gemini+conventional surfactant combinations were found to be dependent upon the length of hydrophobic spacer of the gemini surfactant.The excess Gibbs free energy of mixing was evaluated,and it indicated relatively more stable mixed micelles for the binary combinations.     

电解质溶液中牛血清白蛋白分子相互作用的动态光散射研究

溶液中粒子斥与吸引作用力,这种依赖关系可以通过作用参数λ来的扩散系数对浓度的依赖关系主要取决于粒子在溶液中所占的体积分数和粒子间的排表示。本研究利用动态光散射技术测量了不同离子强度下牛血清白蛋白分子的扩散系数,求出了相应条件下的λ值。结果表明,在低离子强度下,λ是正值,蛋白质分子间的作用以排斥力为主,随着离子强度的逐渐增大,λ变为负值,蛋白质分子间的作用以吸引力为主,当离子强度大于0．5mol／L的时候,蛋白质开始发生聚集。利用DLVO理论的两体硬球相互作用模型解释了蛋白质分子间相互作用的变化规律：随着离子强度的增加,静电斥力被屏蔽,范德华分子作用力起主要作用。根据值与离子强度变化的相关性,回归出了蛋白质参数：在实验条件下,蛋白质所带的有效电荷Zr=-9．0e、Hamaker常量AH=2．8kBT。实验结果表明：动态光散射技术可以有效地用来研究蛋白质分子间的相互作用。     

两相催化1—十二烯氢甲酰化反应中混合胶束的作用研究

研究了RhCl(CO)(TPPTS)2催化-1-十二烯氢甲酰化反应中,十六烷基三甲基溴化铵（CTAB）与十二烷基硫酸钠（SDS）形成的混合胶束对反应的促进作用。研究结果表明,随SDS在混合表面活剂溶液中比例的增大,1-十二烯生成醛的转华率先增大后又降低,并从混合胶束的临界胶束浓度及混合胶束对底物增溶作用的变化对这一结果进行了讨论。