No abstract

Materials and Methods Accessibility of siRNA in siRNA lipoplexesFA-PEG-modified siRNA lipoplexes and FA-PEG-and PEG-modified siRNA lipoplexes were prepared by mixing at charge ratios (+:-) of 1:1~4:1. Amounts of free siRNA in the siRNA lipoplexs were measured using exclusion assays with SYBR ® Green I Nucleic Acid Gel Stain (Takara Bio Inc., Shiga, Japan) and calculated based on the standard curves of free siRNA as previously reported [1].Cellular uptake of FA -PEG-modified siRNA lipoplexes KB cells were plated into 35-mm culture dishes at a density of 3 × 10 5 cells 24 h prior to each experiment. LP-0.5F5, LP-1F5, LP-2F5, and LP-3F5 lipoplexes with 50 pmol Cy5-siRNA were diluted in 1 mL of folate-deficient RPMI-1640 medium, and they were incubated with KB cells for 3 h. After the incubation, the cells were fixed with 4% formaldehyde. The localization of Cy5-siRNA was visualized using an Eclipse TS100-F microscope (Nikon, Tokyo, Japan).