Rapid and sensitive fluorometric analysis of novel galactosylated cationic liposome interaction with siRNA

RNA interference (RNAi) is being harnessed for application in the gene knockdown approach to the treatment of disease conditions. Targeted delivery of small interfering RNA (siRNA) is however an important consideration for application of this technology. We report here on the preparation of two new hepatocyte-directed liposomes designed for this purpose, containing the cholesteryl cytofectins 3 beta[N-(N', N'-dimethylaminopropane)-carbamoyl] cholesterol (Chol-T) and 3 beta[N-(N', N', N'-trimethylammonium propane)-carbamoyl] cholesterol iodide (Chol-Q). Further we describe a simple yet sensitive fluorometric assay based on the displacement of siRNA-bound SYBR Green, to monitor the association of the duplex RNA with cationic liposomes under the conditions of high dilution encountered in transfection experiments.