Microvortex-induced turbulent mixing for reconstitution of high-density lipoprotein-mimicking nanoparticles with aggregation-prone phosphatidylcholine.

Lipid nanoparticles often contain a phosphatidylcholine with a long chain fatty acid, 1,2-distearoyl--3-phosphocholine (DSPC). However, their preparation often encounters difficulties such as the inability to yield <20 nm nanoparticles due to the aggregation-prone behavior of DSPC. High-density lipoproteins (HDLs) are ∼10 nm protein-bound lipid nanoparticles in our body, and microfluidic preparations of HDL-mimicking nanoparticles (μHDL) have been reported. Herein, we report a new microfluidic mixing mode that enables preparation of μHDL with DSPC in high yield (≥90% on a protein basis). The critical mechanism of this mode is a spontaneous asymmetric distribution of the ethanol flow injected in a symmetric manner followed by turbulent mixing in a simple rectangular parallelepiped-shaped chip.