Fig. 3.

Lipid nanoparticle formation utilizing a microfluidic platform with a staggered herringbone micromixer (SHM). Within the microfluidic channels, the SHM allows the aqueous phase (containing the nucleic acids, e.g. mRNA, under an acidic pH) and the water-miscible organic phase (containing the lipids and cholesterol) to proceed from laminar flow (pre-SHM) through several cycles of chaotic mixing until complete mixing of the phases has occurred (cycle 15). This process facilitates the complexation of cationic/ionizable lipids (dark pink) with the nucleic acids and the formation of micelles and early particle structures formed by the lipid mix, typically consisting of a cationic/ionizable lipid, a helper lipid (orange), cholesterol (brown), and a PEG-lipid (light pink), and eventually mRNA-encapsulated lipid nanoparticles.