Fig. 3: Identification of filled and empty inverse hexagonal structures.

a Representative cryoTEM and FFTs of 49PE-LNP-noRNA showing two distinct structures: straight lines and hexagons. Scale bars are 50 nm. b Quantification of lattice spacings of structures found in 49PE-LNP at different RNA amounts: no RNA (n = 63, 4.78 nm ± 0.11 nm), NP = 6 (total: n = 77, 5.31 nm ± 0.67, low population: n = 50, 4.84 nm ± 0.16 nm, high population: n = 27, 6.20 nm ± 0.17 nm) and NP = 1 (n = 81, 6.06 nm ± 0.13 nm). c Schematic representation of ‘empty’ and ‘filled’ inverted hexagonal structures. d CryoET slices of 3 separate 49PE-LNP-noRNA particles. Identified spherical and tubular structures in each slice are indicated as blue circles and yellow lines respectively. Scale bars are 50 nm. Tomogram is a representative selection of triplicate of reconstructions. e Reconstruction of the three-dimensional tomogram shown as the middle LNP in (d). f CryoET slices through an individual 49PE-LNP-NP1 particle. EM images represent slices at two different heights of the tomogram, showing straight lines (top) and hexagonally packed regions (bottom). Scale bars are 50 nm. g Surface rendering indicates internal liquid crystalline structures. h Fitted siRNA-lipid models to the electron density derived from cryoET, showing different orientations of the same structure (RNA in purple, lipid tails in yellow). Abbreviations used: NP = Nitrogen to phosphate ratio. Source data are provided as a Source Data file.