Abstract: AIMTo investigate factors affecting the properties of antisense oligodeoxy nucleotides (ASON)-liposomes complex and their cellular uptake. METHODSThree types of blank liposomes were prepared by reverse-phase evaporation vesicles, and the complex were obtained through physical absorption. The light microscope was used to observe morphology characteristics of the complex. Drug loading capacity was analyzed by agarose gel electrophoresis. The transfected cell percentage and means fluorescence intensity were determined by flow cytometric analysis using M₃ myeloma cell as a model. RESULTSThe neutral liposome showed no aggregation while the cationic liposomes appeared some different extent aggregation in different medium when associated antisense oligodeoxynucleotides. The drug loading capacity depended on the ratio of +/- and the cationic charge density on the lipid membrane. The two kinds of cationic liposomes appeared different principles of loading ASON. As far as cellular uptake, The neutral liposomes showed no improvement of cellular uptake of ASON. However, the cationic liposomes were shown to enhance the cellular uptake of ASON if the appropriate +/- charge ratio was used. The optimal cellular uptake was achieved when +/- charge ratio was at 0.5∶1 and 1∶1 for SA-I liposome and SA-II liposomes,respectively. CONCLUSIONThe cationic liposomes improved the loading capacity and cell uptake of antisense oligodeoxynucleotides, which was determined by +/- charge ratio and charge density.