Preparation Of Spin Trapping Liposome And Its Character Study

Liposome is used as a carrier of drugs was extensively studied in recent years. In this study, liposome loaded with two spin traps, were discussed. It was reported that this way will improve the stability and targeting of the spin traps to a certain extent.PBN (N-tert-Butyl-α-phenylnitrone), a model of spin trap, liposome, was prepared by the film-ultrasonic technique. The orthogonal design was applied to the optimization of the preparation technology on the basis of the single factor evaluation. The entrapment ratio of the PBN liposome was 74.38%, and the mean diameter was 100.8nm. BMPO(5-tert-Butoxycarbonyl5-methyl-l-pyrrolineN-oxide)liposomes were made by Reverse-phase Evaporation Vesicle method. Orthogonal design was applied to optimize the preparation technology on the basis of the single factor evaluation. By investigated the entrapment efficiency, the appropriate quantity of lecithin, pH of the buffer, the time of ultrasonic and the volume of buffer for hydration were studied. The particle size of the resulting BMPO liposome was 125.9nm, the entrapment efficiency and drug loading were 92.02% and 2.30% respectively.The effect of PBN liposome on HepG2 hepatoma cells and normal Chang liver cells was analyzed and compared. The affinity of PBN liposome to cells was assessed through monitoring the concentration of PBN in cells by HPLC, and the growth inhibition of PBN liposome to cells was analyzed by MTT method. The results show that the concentration of PBN in cells was in a dose and time dependent manner; PBN liposome had higher affinity to liver cell than free PBN. The growth inhibition in HepG2 hepatoma cells in response to PBN liposome was stronger than that in normal Chang cells.The purposes are to prepare magnetoliposome (MLP) containing PBN encapsulated magnetite (Fe₃O₄) by sonic-film method, and to examine its physicochemical properties and its in vivo behavior on SD mice. Then the basic properties of MLP and in vivo distribution were studied. The results were that the mean diameter of MLP was 304.4nm and the final concentration of encapsulated Fe₃O₄ was170.224mg·L^-1.Most of the MLP were taken up by liver after the administration via tail vain, but the liver distribution of SD mice with the magnetic field is larger than natural conditions. The formulation was stable and encapsulated high amount of Fe₃O₄.The delivery system could be oriented to certain tissues under magnetic field and satisfying magnetic responsiveness was observed. The results indicated that PBN magnetic liposome has apparent characteristic of targeting to liver.