Studies On Nano-drug Delivery System Of Co-delivery Of Gene And Doxorubicin

The combination of chemotherapy and gene therapy may provide a method for overcoming multidrug resistance in cancer therapy. And the choosing of a kind of gene delivery carriers that with low toxocity and can transfer DNA into the nuclei of target cells with highly expression efficiency is a key factor for success of combination therapy. Cationic liposomes have been proposed as biocompatible gene delivery vectors, able to overcome the barriers imposed by cell membranes. Besides lipids, other surfactant molecules have been successfully used in the composition of gene carriers. Gemini surfactants are a new class of surfactant with two hydrocarbon chain, two ionic group, and a spacer linked them . In the present study, people do some physicochemical study on the interactions between plasmid DNA and liposome. And liposome/DNA complexes were prepared by mixing them and were examined as an efficient and gene delivery carriers. Besides, the codelivery system liposome/DNA/DOX complexes were prepared successfully and evaluated in the use of co-delivery system was examined. The results in this study are as follows:(1) Cationic liposomes were prepared by the film dispersion method. We investigated the size and zeta potential, morphology and physical stability of these plain lipid carriers. The results showed that the repeatability of the preparation technologies was well and the liposomes were stabile.(2) Agarose gel electrophoresis and the size and zeta potential of liposome/DNA complexes were measured to characterize the phsician of DNA in the liposome/DNA complexes. And circular dichroism (CD) was used to study the changes of DNA conformational in the liposome/DNA complexes at different N/P ratio. The results is that different liposomes showed significantly differences in the ability of binding and compacting DNA .The mean size of the liposome/DNA complexes was in the range of 100-130 nm.The zeta potential was increased by the adding of pozitive liposome. At low N/P ratio liposome/DNA complexes has a negative zeta potential .The zeta potentials were positive when the N/P ratio above 1 .(3) To study the compaction of DNA in liposome/DNA complexes, agarose gelelectrophoresis was studied. The fluorescence displacement and exclusion experiment was used to studied the differention of linking DNA in the four kinds of liposomes. Particle size and zeta potential was measured at different N/P ratio. To assess the cytotoxicities of the liposome, MTT assay was employed in A2780 cell line. Transfection experiment was determined by EGFP and Luccmv with A2780 cell line to search for a suitable and higly transfection efficiency of the complexes. The results showed that liposome and DNA can form a stable and compacted complexes when N/P ratios= 1. The cytotoxicities of the complexes in A2780 cells were low. In serum-free medium, the liposome can delivere DNA into the cells efficiently with a highly gene expression efficiency. Furthermore, the best N/P ratios for transfection was 1, Which was below the fully condensed point.(4) We prepared liposomes/DNA/DOX complexes. And the releasing of DOX was tested. Besides, transfection efficiency of the complexes were determined by the detection of EGFP and cmvLuc. And we can see that DNA was efficiently delivered into the cells with highly transfection efficiency.In conclusion, the transfection efficiency of liposomes was determined by the length and the symmetry of carbon chain line. In addition, liposomes can be used for the co-delivery system.