Vesicle size, laser light scattering

Determination of Vesicle Size by Laser Light Scattering... 

The vesicle size is an important parameter not only for in-process control but particularly in quality assurance, because the physical stability of the vesicle dispersion depends on particle size and particle size distribution. An appropriate and particularly quick method is laser light scattering or diffraction. Laser light diffraction can be applied to particles > 1 pm and refers to the proportionality between the intensity of diffraction and the square of the particle diameter according to the diffraction theory of Fraunhofer. 

Unfortunately, these indices are difficult to determine. Furthermore, most vesicle dispersions contain a dispersed mesophase with particle sizes below 200 nm up to 1 pm. Therefore photon correlation spectroscopy (PCS), on the basis of laser light scattering, provides an appropriate method of investigation [18]. 

Electron microscopy provides direct evidence that the polymerized dispersions still contain spherical liposomes (Fig. 20). Laser light scattering measurements also demonstrate the presence of vesicles in the irradiated dispersions16). The size distribution of vesicles is not significantly altered by polymerization 13) (Fig. 21) as confirmed by gel filtration before and after irradiation of vesicles of (7). 

Mean hydrodynamic diameters of vesicles (liposomes, nanospheres, nanobeads) can be determined by dynamic laser light scattering, e.g. the NICOMP 380 particle sizing instrument, Particle Sizing Systems (Sta. Barbara, CA, USA). 

Uniform Bi2S3 flowers with a size of 3-5 fim, which are composed of nanowires with a diameter of 60-80 nm, can be prepared in large scale by the template effect of the ionic liquid solution, in which vesicles are formed as confirmed by laser light scattering analysis. With prolonged aging time, the flowerlike structures tend to become loose and fall off from the mother flowers, and finally the individual nanowires will form. 

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