Figure 3.

Encapsulated siRNA is immobilized on the NMR time scale. (A) ³¹P signal from free (phosphothioate) siRNA. Note that phosphothioate siRNA, which gives rise to a ³¹P NMR resonance ∼56 ppm downfield of the phosphodiester peak, was used to avoid overlap with the ³¹P NMR signal arising from the DSPC phosphorus. (B) ³¹P NMR spectrum of phosphothioate siRNA encapsulated at a siRNA/lipid ratio of 0.06 (w/w) in LNP containing DLinKC2-DMA/DSPC/Chol/PEG-lipid (40/11.5/47.5/1; mol/mol). (C) ³¹P NMR signal arising from the same sample as (B) after the addition of 1% SDS to solubilize the particle. The spectra depicted were obtained from 15 000 transients as described in the Experimental Section.