| Cationic liposome has great application value in drug delivery system.Bacterial surface protein,S-layer proteins(Slps),have been employed to modify liposome for improving the liposome stability and increasing the gastrointestinal adhesion,owning to their capability to reassemble on the surface of interface.And the Slps coating liposomes can be served as the good oral vaccine carrier.But the interaction information between Slps and positively charged liposome are destitute,as well as the application of oral vaccine carrier with Slps c oating liposomes.In this paper,the extraction methods among three kinds of denaturant were compared by using the purity and concentration of Slps.Finally,the extraction of Slps with 5 M of lithium chloride was determined.Slps extracted from Lactobacillus helveticus were reassembled on the surface of the two positively charged liposomes composed of Eudragit?RL100 and N,N-dimethyl-(N',N'-di-(stearoyl-1-ethyl))1,3-diaminopropane(DMSP)with different protein concentrations.By measuring the change of the potentials,particle sizes and observing the transmission electron microscope of the two kinds of Slps coating cationic liposomes,the dynamic process of the interaction between them would be reflected.With the adding of Slps,cationic liposome of Eudragit?RL100 had a decreasing potential value from +51.6 ± 2.3 mV to +14.6 ± 0.8 mV,cationic liposome of DMSP had a decreasing potential value from +50.8 ± 2.1 mV mV to +39.7 ± 2.4mV gradually as well.However,the particle s ize of cationic liposomes prepared by Eudragit?RL100(158.0 ± 2.1 nm)and the particle s ize of cationic liposomes prepared by DMSP(180.8 ± 10.3 nm)were almost unchanged.In order to investigate the properties of Slps coating liposomes,firstly the fluorescent liposomes were made and the effect of Slps on the fluorescence quenching effect was measured.Mixing the liposomes with octadecylamine fluorescein isothiocyanate grafting at high temperature,different concentrations of potassium iodide were added in fluorescent liposomes solution.After Slps encapsulating the fluorescent liposome,the Slps inhibition for potassium iodide of Eudragit?RL100 cationic liposome had the increasing fluorescence quenching percentage about 7.85~56.29%,DMSP cationic liposome had increasing fluorescence quenching percentage about 9.96%~89.97%.Secondly,comparing the freeze-dried Slps coating liposome powder and Slps,RLP physical mixtures powder by Fouriertransform infrared(FTIR)spectroscopy,it illustrated the existence of Slps coating liposome was the non-covalent bond interaction.At last,we observed that two kinds of cationic liposomes coated with Slps could increase the adhesion of gastrointestinal mucosa.Hepatitis B vaccine(Hep B)(Saccharomyces cerevisiae)was the model drug to investigate the effect of Slps coating cationic liposome as oral vaccine carrier.First,the dual wavelength G250 method was determined for entrapment efficiency test of liposome.Then preparing the Slps coating cationic liposomes carried vaccine with the particle size of 561.2 nm,potential of + 24 mV and vaccine entrapment rate of 85.3% by reverse phase evaporation method(total lipid/hepatitis B vaccine concentration ratio was 100:1 and total lipid /Slps was 5:1).At last The immunoglobulin G(IgG)concentrations in mouse serum were determined by IgG enzyme-linked immunosorbent assay(ELISA)at 8th week,10 week and 12 week after subcutaneously injecting Hep B,intragastric administrating Hep B,intragastric administrating cationic liposomes conveyed Hep B and intragastric administrating Slps coating cationic liposomes conveyed Hep B.The results showed that oral administration of Hep B vaccine group almost had no effect,cationic liposomes conveyed Hep B group and Slps coating cationic liposomes conveyed Hep B group could improve the Hep B vaccine to stimulate the body to produce more IgG.The Slps coating cationic liposomes conveyed Hep B group produces had produced the most IgG in all oral group s,but its immune effects still had some gaps for injection group. |
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