Figure 2.

ApoE binding to LNP as measured by LNP immobilized particles on a QCM-D sensor. The raw frequency shift for overtone 5, 7, and 9 is reported as a function of ApoE concentration (A). The frequency shift has been offset by the equilibrium value obtained after LNP injection/rinsing. The overlap for all overtones suggests that the ApoE is a rigid film adsorbed on the LNP (no change in dissipation occurs). Note that a negative change in frequency is related to an increase in adsorbed wet mass. The number of ApoE molecules per LNP as a function of ApoE concentration is calculated assuming hexagonal (gray squares) and random (black circles) packing by using the Sauerbrey equation (B). Transition of free ApoE⁴⁴ (PDB ID: 2l7b) into proposed hairpin-like configuration⁴³ adapted to fit on an 80 nm diameter LNP (green). Domains bound to the LNP surface are shown in red with hydrophobic leucines and isoleucines shown as sticks (C). The illustration was prepared using the PyMOL Molecular Graphics System, version 2.0, Schrödinger, LLC.