Vesicles in solution

A concise approach for the analysis of isotropic scattering curves of spherical and cylindrical particles with a radial density profile has been developed by Burger [207], In practice it is useful for the study of latices and vesicles in solution. 

Soo PL, Eisenberg A. Preparation of block copolymer vesicles in solution. J Polym Sci B Polym Phys 2004 42 923-938. 

Release of liposome-encapsulated CF from HA/PLL films has been observed at temperatures above the lipid transition temperature (Fig. 4f). Below this temperature, the vesicles were stable at least for a few hours. The polyelectrolyte network destabilizes the embedded vesicles, which show higher lipidic bilayer permeability upon heating than do vesicles in solution [84], No change in film properties upon heating has been reported as proof of the polyelectrolyte destabilization effect. 

The authors also reported on the supramolecular self-assembly from rod—coil—rod triblock copolymers prepared by copolymerization of 5-acetyl-2-aminob-ezophenone with diacetyl functionalized polystyrene with low polydispersity (Scheme 12).110 In contrast to the rod—coil diblock copolymers which exhibit multiple morphologies, the triblock copolymers were found to spontaneously form only microcapsules or spherical vesicles in solution as evidenced by optical polarized, fluorescence optical, and scanning electron microscopies (Figure 33). 

Fig. 22 The stepwise fabrication of vesicle patterns is shown in the sequence of AFM images a-c (image size 20 xm x 20 xm). The scanning probe lithographic modification and the adsorption process of vesicles in solution onto the altered part of the bUayer is depicted schematically in d (no molecular-level structural details of the AFM tip-induced line are implied in the schematic)...

Liposomes or vesicles in solution can be modeled as nonconducting spheres embedded in a conductive medium. The measured capacity of the ensemble of vesicles is converted to a capacitance per unit area of membrane surface which, in turn, determines the membrane thickness. 

Double-chain quaternary ammonium surfactants on mica show fiat, featureless images [22] consistent with previous models of a uniform bilayer [11]. In this case no conflict exists between preferred curvature in solution and that at the surface, since dialkyl-dimethylammonium surfactants form bilayers (and vesicles) in solution. 

These researchers subsequently showed that these CB[8]-encapsulated charge transfer pairs can act as supramolecular amphiphiles, and spontaneously form vesicle in solution [140], They were able to investigate the structure and physical properties of these vesicles, which had a typical diameter of around 400-950 nm as indicated by SEM images. Furthermore, TEM images... 

Vesicles are bilayers that have folded into a three-dimensional spherical structure, sort of like a micelle with two layers of molecules. Vesicles form because they get rid of the edges of bilayers, protecting the hydrophobic chains from the water, but they still allow for relatively small layers, hi order for a flat bilayer to exist without edges, it must have infinite length. Molecules that form vesicles usually have a fluid double chain and a large optimal area. Lipids found in biological membranes spontaneously form vesicles in solution. 

Figure 17.5 Reversibility of vesicles in responsive to increasing or decreasing water content for PAA44-Z7-PS300 in THF/dioxane. (Reprinted with permission from L. Luo and A. Eisenberg, Thermodynamic size control of block copolymer vesicles in solution, Langmuir, 17, 22, 6804-6811, 2001. 2001 American Chemical Society.)...

Luo, L. and Eisenberg, A. (2001) Thermodynamic size control of block copolymer vesicles in solution. Langmuir, 17,6804-6811. 

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