Drug-Induced Phase Transition from Cubic Phase to Vesicle

The effect of caffeine on the phase behavior of aqueous dispersion of cubic phase was studied. The morphologies of the dispersed particles were observed by means of cryo-transmission electron microscopy (TEM) and the sizes of the dispersed particles were determined by dynamic light scattering (DLS). It was found that the addition of caffeine could lead to the phase transition from cubic phase to vesicle, and this might be due to the “salt out” effect of caffeine on the monoglyceride molecules in aqueous phase.     

二氧化钛纳米晶囊泡微乳液在聚氨酯涂饰体系中的应用

以钛酸丁酯为原料,十六烷基三甲基溴化铵与十二烷基苯磺酸钠自组装形成的囊泡为微反应器,制备了二氧化钛纳米晶囊泡微乳液.将二氧化钛纳米晶囊泡微乳液与水性阳离子聚氨酯复配,得到聚氨酯/TiO2囊泡微乳液(UPC/TVM)复合皮革涂饰剂,采用TEM、马尔文粒径分析和紫外漫反射等方法,研究了TiO2囊泡微乳液和聚氨酯配比对涂饰剂分散、成膜、涂饰性能的影响.研究结果表明,TiO2囊泡微乳液与聚氨酯形成均一的微乳液,粒径尺寸在80 nm左右.TiO2囊泡微乳液的加入,使得UPC/TVM3膜与UPC膜相比,抗张强度、断裂伸长率和吸水性都有所提高并出现明显的抗紫外效果.UPC/TVM复合皮革涂饰剂应用实验结果表明涂层的抗水性提高,耐折性能没有改变.     

A sensitive amperometric sensor for hydrazine and hydrogen peroxide based on palladium nanoparticles/onion-like mesoporous carbon vesicle

Onion-like mesoporous carbon vesicle (MCV) with multilayer lamellar structure was synthesized by a simply aqueous emulsion co-assembly approach. Palladium (Pd) nanoparticles were deposited on the MCV matrix (Pd/MCV) by chemical reduction of H₂PdCl₄ with NaBH₄ in aqueous media. Pd(X)/MCV (X wt.% indicates the Pd loading amount) nanocomposites with different Pd loading amount were obtained by adjusting the ratio of precursors. The particular structure of the MCV results in efficient mass transport and the onion-like layers of MCV allows for the obtainment of highly dispersed Pd nanoparticles. The introduction of Pd nanoparticles on the MCV matrix facilitates hydrazine oxidation at more negative potential and delivers higher oxidation current in comparison with MCV. A linear range from 2.0 × 10⁻⁸ to 7.1 × 10⁻⁵ M and a low detection limit of 14.9 nM for hydrazine are obtained at Pd(25)/MCV nanocomposite modified glassy carbon (GC) electrode. A nonenzymatic amperometric sensor for hydrogen peroxide based on the Pd(25)/MCV nanocomposite modified GC electrode is also developed. Compared with MCV modified GC electrode, the Pd(25)/MCV nanocomposite modified GC electrode displays enhanced amperometric responses towards hydrogen peroxide and gives a linear range from 1.0 × 10⁻⁷ to 6.1 × 10⁻³ M. The Pd(25)/MCV nanocomposite modified GC electrode achieves 95% of the steady-current for hydrogen peroxide within 1 s. The combination of the unique properties of Pd nanoparticles and the porous mesostructure of MCV matrix guarantees the improved analytical performance for hydrazine and hydrogen peroxide.     

Didodecyldimethylammonium Bromide Bilayer Vesicle-Catalyzed and Uranine-Sensitized Chemiluminescence for Determination of Free Cyanide at Picogram Levels by Flow Injection Method

Abstract

A novel chemiluminescence system, didodecyldimethylammonium bromide-uranine-sodium hydroxide, is described for the determination of ultratraces of free cyanide by flow injection method. Organized surfactant assemblies(bilayer vesicles) incorporated with a sensitizer (uranine) permit the determination of free cyanide very selectively with a limit of determination of 1 pg (20-μ1 sample injection). Sulfide, the strongest CL inducer after free cyanide, provides a signal 0.1 % of that for free cyanide.     

季铵盐型Gemini表面活性剂诱导囊泡结构改变机理研究

用动态光散射技术以及荧光探针方法, 研究了不同连接基长度的季铵盐型Gemini表面活性剂对卵磷脂囊泡结构改变的影响, 并借助理论模型和临界堆积参数理论探索了Gemini表面活性剂诱导囊泡结构改变的机理. 实验结果表明, 表面活性剂诱导囊泡结构改变的主要原因是表面活性剂嵌入到囊泡的双分子层中, 从而改变了囊泡的表面电荷强度以及嵌入后的表面活性剂在囊泡双分子层中分布的不均匀性. 此外, 表面活性剂分子的结构也会对其产生影响, 不同连接基长度的季铵盐型Gemini表面活性剂对囊泡结构改变的影响不完全相同, 但会呈现出一定的规律性.     

Dissipative particle dynamics simulation study of the bilayer-vesicle transition

A bilayer structure is an important immediate for the vesicle formation. However,the mechanism for the bilayer-vesicle transition remains unclear. In this work,a dissipative particle dynamics(DPD) simulation method was employed to study the mechanism of the bilayer-vesicle transition. A coarse-grained model was built based on a lipid molecule termed dimyristoylphosphatidylcholine(DMPC). Simulations were performed from two different initial configurations:a random dispersed solution and a tensionless bilayer. It was found that the bilayer-vesicle transition was driven by the minimization of the water-tail hydrophobic interaction energy,and was accompanied with the increase of the position entropy due to the redistribution of water molecules. The bulk pressure was reduced during the bilayer-vesicle transition,suggesting the evolved vesicle morphology was at the relatively low free energy state. The membrane in the product vesicle was a two-dimensional fluid. It can be concluded that the membrane of a vesicle is not interdigitated and most of the bonds in lipid chains are inclined to orient along the radical axis of the vesicle.     

可聚合囊泡体系(烯丙基-二甲基-十二烷基溴化胺和十二烷基硫酸钠)在溶液中的盐效应

高稳定的囊泡广泛用于制作生物模型、药物输送以及合成纳米材料的模板。获得高稳定囊泡结构的重要方法之一是用聚合反应固定囊泡结构。作为可聚合囊泡制备的前期基础工作,研究了一种可聚合的囊泡体系：1-丙烯基－2,2,二甲基－十二烷基溴化胺（ADDB）和ADDB与十二烷基磺酸钠（SDS）的等摩尔比混合体系。该囊泡体系即使在高浓度盐水中也能够自发地形成均相的囊泡溶液。在聚合之前,采用动态激光光散射（DLS）、冷冻蚀刻透射电镜（FF-TEM）技术研究了可聚合囊泡的盐效应。DLS测试发现没有盐存在时,囊泡大小为83 nm,盐的浓度增加到250 mmol/L时,囊泡尺寸增大到250 nm。然而继续增大盐浓度到1000 mmol/L, 囊泡尺寸减小到180nm. FF-TEM结果发现盐浓度小于150 mM时, 单个囊泡为70 nm左右,然而明显存在囊泡的絮凝与融合;当盐浓度增加到400 mM时,单个囊泡尺寸减小到20 nm. 因此DLS 观测到囊泡尺寸增大的原因是由于囊泡的絮凝与融合;而尺寸减小的原因是由于在高盐浓度下,盐屏蔽了带电颗粒之间的静电相互作用,在熵增的驱使下,大囊泡变成小囊泡。     

Electron microscopic and light scattering observation on a system with two iridescent phases

Electron microscopic observations and classical light-scattering measurements have been carried out for dodecyldimethylaminoxide/hexanol/water mixtures in the concentration range where iridescent colors occur. This system has two different iridescent phases. The iridescent phase with more hexanol forms quickly, and the phase with less hexanol forms very slowly. Three different isotropic phases which show strong flow birefringence are found near both iridescent phases. The electron microscopic pictures show clearly that only one of these isotropic phases with strong flow birefringence is a bicontinuous sponge phase (L_3h -phase). This is the phase which comes out by adding some alkanol to the upper lamellar phase. The flow birefringent phase below the lower lamellar phase forms unilamellar vesicles. The flow birefringent phase which occurs between both iridescent phases contains multilamellar vesicles and is shown to be a precursor of a lamellar phase.     

高分子微泡体系中光解水的研究：（Ⅱ）聚卵磷脂微泡在光解水中的应用

本文研究以卵磷脂为单体形成的微泡体系,以Co~(60)辐照为聚合方式,通过超声波作用将联吡啶钌和EDTA,甲基紫精和铂溶胶等光解水的试剂置于微泡的不同区域,从而获得不同的光解水效果。