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As nature effective antioxidant, vitamin E plays an important role in food preservation and supply of nutrients, but at the same time sensitive to vitamin E against light, heat, oxygen and other environmental factors, poor water solubility and in vivo absorption rate is low. This issue through polyethylene glycol surface of conventional liposomes modified to entrapped vitamin E, freeze drying against external environmental factors or destruction, to avoid oxidation and loss of physiological activity, while focusing on the vitamin E before fat physicochemical properties and controlled release of plasmid. Film homogenization method and response surface optimization of coated vitamin E polyethylene glycol liposome formulations using the Box-Behnken central composite design principles. The encapsulation rate response values, according to the experimental results of the proportion of the volume of the organic solvent, the ratio of phospholipid to cholesterol, phospholipids, and the core material and the phosphate buffer solution at pH value single factor, design 4 factors, 3 levels response surface optimization experiments, according to the experimental results the linear regression equation to mathematical analysis of the regression equation, and the final selection of the formula as follows: The volume of the organic solvent 26.18mL, phospholipids and cholesterol ratio was 1.62:1, and the ratio of phospholipid and VE as 1.17:1, the pH of the PBS solution was 6.78. Under this condition, according to the selected recipe, conventional liposomes (CL) of the resulting vitamin E encapsulation efficiency of 90.53%, the average particle diameter of 96.7nm. Zeta potential was negatively charged, can be observed under transmission electron microscopy to the liposome surface is smooth, and most of the single-layer structure. Encapsulation efficiency and particle size as index to determine the two-step method for the preparation of polyethylene glycol-coated vitamin E liposomes (PL) method, and when the polyethylene glycol has a mass fraction of 2.0% and a molecular weight of 4000 when the package closure rate of 91.03%, the average particle size of about 111.3nm outer wall than conventional liposomes thick, polyethylene glycol wrap CL phenomenon observed under a transmission electron microscope. Preparation of polyethylene glycol-coated vitamin E lyophilized SYSTEM proliposome: TEM observation after rewatering proliposome (RPLP) there is a certain degree of aggregation, sphere opaque to the film forming conditions can not be observed. ; having irregular and porous structure of the surface of the scanning electron microscope to the lyophilized powder. Complex water after liposome encapsulation efficiency was 83.87%, the particle size of 164.2nm. The liposomes were prepared in three different simulated release medium in vitro release, Cl, PL and RPLP much slower than free release of vitamin E, and the RPLP and PL and CL is compared with the absolute slow release of advantages. The first within 6h CL in simulated intestinal fluid VE release rate of 35%, reached 62.0% after 48 hours. The release rate within the first 6h PL and RPLP, respectively, 17.4% and 16.0%, 53.0% and 54.1% after 48 hours, respectively. After the 48h the release the PL and RPLP in the VE release rate due to the sensitive nature of the acid-polyethylene glycol, when the release medium to strong acidic simulated gastric were 70.9% and 70.1%, respectively, higher than the simulated intestinal fluid and phosphate buffer solution about 15%. After 15 days of storage stability test, the PLPs The retention rate was significantly higher than CL, and stored at 4 ℃ 15 days after the retention rate can be as high as 89.81%. VE, IR spectra indicated that of the polyethylene glycol and the PLP PLP located at 1112.50 cm-1 CO stretching vibration intensity, while the VE benzene ring characteristic peaks from 1208.44 cm-1 moved to 1143.48 cm-1; polyethylene glycol hydroxy peaks from 3489.23 cm-1 moved to 3403.27 cm-1, and the strength are significantly reduced. This shows that the form of electrostatic interactions between the polyethylene glycol and the phospholipid binding polyethylene glycol liposome, such that through the force between the both successfully entrapped VE. Liposome transdermal experiments early existence of the burst effect, with the controlled-release in vitro results are consistent, which indicates that the PLP has good transdermal performance.
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