Formation And Fusion Of Phospholipid Vesicle And Niosome

1. Study on the formation of phospholipid vesiclePhospholipid vesicle is observed by the methods of imaging analysis, negative-staining transmission electron microscope (NS-TEM) and atomic force microscope (AFM), whose particle size of vesicle is about 200 nm. Some fators that effect the phospholipid vesicle is researched such as the concentration of lecithin, sonicate, salt, pH, ethanol and amino acid. The size of vesicle increases with increasing the concentration of lecithin but decreases after sonicating. Vesicle is prepared easily by adding NaCl, but phospholipid vesicle is destroyed when the salt concentration is 0.04 mol/L. And pH impacts less on the lecithin vesicle. Ethanol has a detrimental effect on the vesicle. The vesicle is destroyed when the concentration of phospholipid is small, and the size distribution narrowed when the concentration of phospholipids is large. but the size distribution narrowed. And the size of vesicles increases by adding amino acid. Phospholipid vesicle is Newtonian liquid. Though its viscoelasticitie is very small, it has certain linear viscoelasticities in the low frequency region.2. Study on formation of Span 80/PEG 400/H2O niosomeThe properties of highly stable niosome in Span 80/PEG 400/H2O system are further systemic researched. The morphology of vesicle is observed by use of atomic force microscope, and the particle size is measured with dynamic light scattered. It is researched that the effects on niosome of the concentration of PEG 400 and water, pH, amino acid. The absorbance of niosome increases with increasing the concentration of surfactant. Since the winding structure of Span 80 and PEG 400 makes the presence of fluorescence, the intensity of fluorescence increases with adding the concentration of surfactants. The size of niosome decrease first slowly and then has sharp decline with increasing the PEG 400 content. And the number of vesicles decreases gradually With increasing water content. In the range of 5-7, the number of vesicles decreases with pH increaseing. There is the coexistence of vesicles and microspheres after the addition of amino acid. By the view of viscosity and viscoelasticity, rheological properties of Span 80/PEG 400/H2O niosome are studied. Span 80/ PEG 400/ H2O niosome is Newtonian liquid. The factors that effect on vesicle such as viscosity of water content, PEG 400 content, the concentration of salt and amino acid are considered and the viscoelasticity is researched through oscillation test. The viscosity of niosome decreases with increasing water content. The addition of NaCl makes the viscosity of niosome have an ascent after a initial decline trend. When PEG 400 content is increased, the viscosity of niosome increases gradually. And the viscosity increases slightly by adding amino acid. Though its viscoelasticitie is very small, it has certain linear viscoelasticities in the low frequency region.3. Study on the behavior of vesicle fusion of niosome and phospholipid vesicleThe dynamic fusion of Span 80/ PEG 400/ H2O niosome system and phospholipid vesicles is observed and recorded by use of imaging analysis techniques in normal condition. And the result shows that the rate of fusion of phospholipid vesicles is faster than Span 80/ PEG 400/ H2O niosome. The fusion process of Span 80/ PEG 400/ H2O niosome can last about 2 min, but that of phospholipid vesicles ends within one minute. The membrane fusion mechanism is proposed that the process of vesicle fusion occurred through closing, contact, semi-fusion, pore formation, pore expansion of vesicle membrane. Then the change of Gibbs free energy in niosome and phospholipids vesicle system is calculated.