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. Author manuscript; available in PMC: 2014 Jul 1.
Published in final edited form as: Biomaterials. 2013 Apr 1;34(20):4839–4848. doi: 10.1016/j.biomaterials.2013.03.021

Figure 2. Effect of PLL block length, modifying siRNA with 3’-cholesterol, and complexation with nuclease-resistant Chol-siRNA on protection of complexed siRNA from degradation in high serum concentrations by PLL-PEG(5K).

Figure 2

(A) siRNA (siCtrl: 5’- UGG UUU ACA UGU CGA CUA A - 3’ with 3’-UU overhangs), (B) Chol-siRNA (siCtrl modified with 3’-cholesterol on the sense strand), or (C) nuclease-resistant Chol-*siRNA (Chol-siCtrl without 3’-UU overhangs on the sense stand) was incubated with PLL-PEG(5K) in HEPES buffer at room temperature for 30 min at the indicated minimum N/P ratio required for complexation. Polyplexes were then incubated in the presence or absence of 90%v/v murine serum at 37°C for the indicated time, disassembled by heparin, and resolved with or without water solubilized cholesterol (*Cholesterol) as described in Fig.1. The single band for (A) truncated siRNA (open symbols), (B) full-length Chol-siRNA (closed symbols), or (C) full-length Chol-*siRNA (closed symbols) from serum-treated polyplexes was quantified by densitometry and normalized to the respective full-length band from untreated polyplexes at the same N/P ratio. Percent protection ± SD (n=2) is an average of two independent experiments. siRNA and Chol-siRNA were completely degraded within 1 h and Chol-*siRNA was degraded within 1.5 h under the same conditions.