Process Robustness in Lipid Nanoparticle Production: A Comparison of Microfluidic and Turbulent Jet Mixing

The recent clinical and commercial success of lipid nanoparticles(LNPs) for nucleic acid delivery has incentivized the developmentof new technologies to manufacture LNPs. As new technologies emerge,researchers must determine which technologies to assess and how toperform comparative evaluations. In this article, we use a quality-by-designapproach to systematically investigate how the mixer technology usedto form LNPs influences LNPstructure. Specifically, a coaxial turbulentjet mixer and a staggered herringbone microfluidic mixer were systematicallycompared via matched formulation and process conditions. A full-factorialdesign-of-experiments study with three factors and three levels wasexecuted for each mixer to compare process robustness in the productionof antisense oligonucleotide (ASO) LNPs. ASO-LNPs generated with thecoaxial turbulent jet mixer were consistently smaller, had a narrowerparticle size distribution, and had a higher ASO encapsulation ascompared to the microfluidic mixer, but had a greater variation ininternal structure with less ordered cores. A subset of the studywas replicated for mRNA-LNPs with comparable trends in particle sizeand encapsulation, but more frequent bleb features for LNPs producedby the coaxial turbulent jet mixer. The study design used here providesa road map for how researchers may compare different mixer technologies(or process changes more broadly) and how such studies can informprocess robustness and manufacturing control strategies.