Fig. 2: The si < (EG18L)2 structure achieves the longest circulation half-life and highest albumin association in plasma.
Cy5-labeled conjugate or parental siRNA structures were delivered i.v. to mice at 1 mg/kg. a Representative images of intravascular Cy5 fluorescence measured in mouse ear vasculature at 0 min and 30 min after treatment are shown. b Intravascular Cy5 fluorescence recorded over ~1 h following delivery was used to calculate absolute siRNA circulation half-life (t1/2). Each point represents the half-life calculated from an individual mouse (n = 3–4). c Cy5 fluorescence in kidneys, lungs, liver, spleen, and heart was measured ~1 h after treatment. Fluorescence values in kidneys relative to the total fluorescent values of all organs combined is shown; each point represents the ratio from an individual mouse (n = 3). d, e Plasma samples collected from mice ~1 h after treatment were fractionated and quantitated for Cy5 fluorescence by size exclusion chromatography. A representative trace is shown of fluorescence signal within each plasma fraction for each siRNA structure; the albumin-containing plasma fractions are highlighted. d Cy5 fluorescence within the albumin-containing fractions was quantitated relative to total plasma fluorescence. Each point represents the plasma taken from an individual mouse (n = 3) (e). For (b, c, e), each bar represents the average value (± S.D.). For (b, c), significance was determined using one-way ANOVA with Tukey’s multiple comparisons test. For (e), significance was determined by one-way ANOVA with Dunnett’s multiple comparisons test using si-PEG45 < L2 as the comparison group.
