Figure 4.

Serum stability of siRNA after complex formation. Representative image of gel electrophoresis and a bar graph summarizing the percentage of intact siRNA after 24 h of exposure to serum at 37 °C for linear (A) and cyclic (B) peptide/siRNA complexes at peptide/siRNA w/w ratios of 2.5–10 and 20–80, respectively. PC and NC represent positive control (scrambled siRNA exposed to saline for 24 h at 37 °C, quantified as 100%) and negative control (representing “naked” siRNA incubated with serum for 24 h at 37 °C), respectively. Linear and cyclic peptides conjugated with C16 and C18 fatty acids as well as the unconjugated cyclic peptide showed the most protection against enzymatic degradation of siRNA. Data are presented as mean, n = 3, and the error bars represent standard deviation.