Synthesis And Properties Of Mannose-based Cationic Liposomes For Gene Delivery

The cationic lipids is become one of the most potential non-viral vectors, because of them have the potential advantages of low cell toxicity, none immune response, easy preparation, easy facilitate inspection and simple storage.In this paper, two series of mannose-based cationic lipids were synthesized. One series of cationic lipids with different lengths of hydrophobic chains attached to the sugar ring such as di-C12-Man-TMA,di-C14-Man-TMA, di-C16-Man-TMA, di-C18-Man-TMA, were constructed from mannose via acetylation, selective deprotection of1-O-acetyl, trichloroacetimidation, glucosidation, azidation, deacetylation,4,6-O-benzylidenation, Williamson etherification, debenzylidenation,reductive amination and quaternarization. The other series of cationic lipids with different lengths of hydrophobic chains attached to the headgroup such as Man-DiC12 MA, Man-Di C14 MA, Man-DiC16 MA,Man-DiC18 MA were prepared from mannose via acetylation, selective deprotection of 1-O-acetyl, trichloroacetimidation, glucosidation,azidation, deacetylation, reductive amination, tertiary amination and quaternarization.Dissolved the lipids in double distilled water, the solution was ultrasonic until clear. Then the liposome/DNA complexes were preparedby combining liposomes with plasmids DNA with EGFP. Cationic lipids and complexes had a regular spherical surface by atom force microscopy.The average particle size, size distribution and zeta potential of cationic lipids and complexes were detected using Zetasizer Nano ZS. Results indicated that the average practical size of the lipids di-C18-Man-TMA and Man-DiC18 MA were 624.1 nm, 502.2 nm respectively. Larger size of the lipids not contribute to gene transfection experiments. The size of other lipids and lipid-DNA complexes were 40-200 nm and 60-200 nm respectively. The zeta potential of cationic lipids were more than 35 mv expect the lipid di-C18-Man-TMA was 26 mv. The DNA binding ability of the cationic lipids were assessed by gel retardation assay. Results suggested that the binding capability of DNA to lipids increased with the proportion for deliver reagent in the complex(N/P), and the DNA delay action was strengthened. When the N/P ratio was increased to 3 : 1, the lipids was fully integrated with the plasmid DNA. These results showed that the cationic liposomes is suitable for transfection of plasmid DNA.By using Lipo2000 as the positive control, the lipids were applied to transfer pEGFP into in HEK293 cell lines. The results showed that the lipids with the hydrophobic tails in the sugar-ring had poor transfection efficiency. However, the lipids with hydrophobic tails in the headgroup had higher efficiency. Among of them, lipids Man-Di C16 MA were most effective in transfer pEGFP.Furthermore, the lipids Man-DiC14 MA and Man-DiC16 MA were applied to transfer pEGFP into Hela and HepG2 cell lines. The results showed that Man-DiC16 MA possessed better transfection efficiency in Hela and HepG2 cell, but is lower than Lipo2000; Man-DiC14 MA has no transfection efficiency.