Research Of Vitamin C-containing Liposome

In this paper, vatimin C-containing lipome was researched. On the basis of studying the stability of vitamin C, choosing the proper film material of lipome and the methods for preparing liposome and measuring encapsulation, one-factor tests and response surface analysis were carried out to get optimum conditions.Then the stability of vitamin C-containing liposome was evidently improved by coating PEG.Under the light-avoiding, low-temperature, acidic or neutral condition, vitamin C was stable and its preservation rate was still above 90% in 24 hours. Comparing with the liposomes which were prepared by alkylpolyglucosides, span and tween surfactants, the liposome prepared with lecithin had better stability. The film dispersion-ultrasonic emulsify method was taken, because of the stability of vitamin C. The free vitamin C was separated from liposome by dialysis in deionized water for 16 hours, and the encapsulation was measured by RP-HPLC.The optimum conditions determined by one-factor tests and response surface analysis were as follow: the ratio of lecithin and cholesterol was 9.61︰1(w/w), pH of PBS was 6.52 and the quality of vitamin C was 1.28g. The encapsulatin of vitamin C liposome prepared under this condition was 41.47% averagely, close to 41.61% resulted from response surface analysis. And the result recured all right. The PEG-coated vitamin C-containing liposome was prepared by simply mixing the liposomal suspension with the PEG solution. The best PEG for coating was PEG1500, and when its concemtration was 3%, the encapsulation was 56.88% maximally.The structure determined by electron microscope confirmed the existence of polymer on the surface of liposome particles and those particals were in the shape of pellet. By comparison with the non-coated liposome whose diameter was 300nm approximately, the polymer coated one with 450nm had larger particle size.The physical and chemical stability of lipome was investigated by measuring the changes of diameter, leakage rate and the malondialdehyde(MDA) content. With the time going up, the particals would assemble, the leakage rate would increase and the lecithin would be oxidated. However, these changes were evidently restrained by coating PEG 1500.