Polarized fluorescence and absorption spectroscopy of 1,32-dihydroxy-dotriacontane-bis-rhodamine 101 ester. A new and lipid bilayer-spanning probe

We report on the properties of 1,32-dihydroxy-dotriacontane-bis-rhodamine 101 ester (Rh101C₃₂Rh101) in lipid bilayers of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and in liquid solvents. The results are compared with those of rhodamine 101 octadecanyl ester (Rh101C₁₈). Both molecules are solubilized in the lipid bilayer and the Rh101 moieties are anchored in the lipid-water interface, so that the electronic transition dipole moments (S ₀ S ₁) are oriented preferentially in the plane of the bilayer. At low concentrations of the dyes in lipid bilayers of DOPC, the fluorescence relaxation is single exponential with a lifetime of =4.9±0.2 ns. The relative fluorescence quantum yield of _C32/_C18 0.95 in DOPC vesicles. These results strongly suggest that only a small fraction of the Rh101C₃₂Rh101 molecules are quenched, by, for example, intra- or intermolecular dimers in the ground state at mole fractions of less than 0.1% in the lipid bilayers. For Rh101C₃₂Rh101 in lipid vesicles, the steady-state and time-resolved fluorescence anisotropies are compatible with efficient intramolecular electronic energy transfer. It is concluded that nearly every Rh101C₃₂Rh101 molecule is spanning across the lipid bilayer of DOPC.     

油酸囊泡层状液晶作为模板电化学合成银纳米颗粒

在油酸囊泡的层状液晶中利用电化学沉积法成功地制备了银纳米颗粒。并用扫描隧道显微镜(STM)和透射电子显微镜(TEM)对银纳米颗粒进行了表征，发现银纳米颗粒能够均匀地分散在油酸囊泡中，并且油酸囊泡能够有效地阻止产生的银纳米颗粒发生聚集反应。此外，我们还提出了银纳米颗粒形成的机理。     

The Nature and Efficiency of Neurotransmitter Exocytosis also Depend on Physicochemical Parameters

Exocytosis is an important biological process used by cells to deliver messengers or effectors to target cells with high spatial, quantitative, and kinetic precision. This process occurs by interaction and fusion of vesicles containing the (bio)chemical information with the cell membrane to release their contents into the surrounding medium. Because of its importance for life, this mechanism underlies many biological controlling factors, including different families of proteins and enzymes. Tremendous efforts have been made over the last decade toward their determination. However, in parallel, many studies have also shown that the physical and chemical characteristics of the exocytosis actors (vesicle, membrane, and extracellular medium) could directly affect the quantitative or kinetic features of secretion. The major pieces evidence for this influence, which have been reported in the literature, are reviewed herein. It demonstrates undoubtedly that pure biological aspects cannot be segregated from the physicochemical context of living mechanisms.     

磷脂酰乙醇胺型聚磷酸酯脂质体膜材的合成

以Ｐ，Ｐ－二氯磷酸β－－氯乙酯与季戊四醇的双脂肪酸酯为单体，通过缩聚反应合成磷酸酯，再经氨基化制备了四种磷酰乙醇胺型聚磷酸酯脂质膜材，用逆相蒸发法制备了脂质体，偏光显微镜及电镜表明，脂质体为大单层，以５－氟尿嘧啶为模型药物进行包封，测定了包封率和体外释放性能。     

Effects of Added Urea and Alkylureas on Gel to Liquid-Crystal Transitions in Doab Vesicles

The gel to liquid-crystal transition for vesicles in aqueous solution formed by dimethyldi-n-octadecylammonium bromide (DOAB) occurs at 44.7°C. Moreover, the shapes of the scans recorded by a sensitive DSC microcalorimeter are very similar when the vesicular solutions are prepared starting with solid DOAB and comparable amounts of either solid urea or solid alkylureas. Therefore, the DOAB vesicles in aqueous solution accommodate this class of solutes without marked changes in the melting temperature and the enthalpy of the transition. The contrast with effects of added surfactants and simple organic solutes such as THF and ethanol is particularly significant. This revised version was published online in August 2006 with corrections to the Cover Date.     

Colorimetric detection of oligonucleotides using a polydiacetylene vesicle sensor

A new system for the colorimetric detection of oligonucleotides was developed using polydiacetylene vesicles, which play the dual role of an indicator of color transition and an amplification tag. The results are of significance in understanding the mechanism of color transition of biological recognition in polydiacetylene systems and in designing new biosensors.     

Control of mechanically activated polymersome fusion: Factors affecting fusion

Previously, it was found that extruded (200 nm) polymer vesicles are capable of fusion into giant polymersomes using agitation in the presence of salt. In this study, several factors contributing to this phenomenon, including the effects of (i) polymer vesicle concentration, (ii) agitation speed and duration, and (iii) variation of the salt and its concentration are investigated. To accomplish these goals dynamic light scattering is used in conjunction with fluorescence microscopy, which provides insight into vesicles above the practical limit for DLS characterization. Increasing the concentration of the polymer dramatically increases the production of giant vesicles through the increased collisions of polymersomes. Likewise, increasing the frequency of agitation increases the efficiency of fusion, although ultimately the size of vesicle that could be produced is limited due to the high shear involved. Finally, salt‐mediation of the fusion process was not limited to NaCl, but is instead a general effect facilitated by the presence of solvated ionic compounds, albeit with different salts initiating fusion at different concentrations. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 297–303     

Synthesis and Vesicle Formation of Ethyl 2-[2′-(F-alkyl)ethyl] 2-alkyl Malonic Acid Disodium Salts

Abstract

A series of new di-anionic perfluoroalkylated amphiphiles with mixed F-alkyl/alkyl long chains and a malonic acid disodium salt head group has been synthesized. Among these new F-alkyl-containing amphiphiles, some were found to self-assemble in stable vesicles by hand shaking in water at room temperature. The vesicular aggregates were viewed by freeze-fracture electron microscopy and measured with photon correlation spectroscopy. Surface-activity of all amphiphiles was also investigated. Their CMCs were in particular determined from curves giving surface tension versus concentration.     

Vesicles in Nature and the Laboratory: Elucidation of Their Biological Properties and Synthesis of Increasingly Complex Synthetic Vesicles

The important role of vesicles in many aspects of cell function is well‐recognized, but only recently have sophisticated imaging techniques begun to reveal their ubiquity in nature. While we further our understanding of the biological properties of vesicles and their physiological functions, increasingly elegant artificial vesicles are being developed for a wide range of technological applications and basic research. Herein, we examine the state of the art of biological and synthetic vesicles and place their biological features in the context of recent synthetic developments, thus providing a unique overview of these complex and rapidly developing fields. The challenges and opportunities associated with future biological and synthetic studies of vesicles are also presented.