(224h) Translation of Lnp Mixing Conditions By Micromixing Time Mapping

Lipid nanoparticles (LNPs) are a versatile non-viral nucleic acid delivery platform for various vaccine, protein replacement, and gene editing therapies. LNPs are formed by rapidly mixing an aqueous stream of nucleic acid payload(s) and an ethanolic stream of ionizable and helper lipids. This nanoprecipitation process is considered to have profound impacts on physicochemical attributes of the resultant particles and efficacy of the final drug product. Consequently, the mixing conditions must be repeatedly optimized throughout the product development cycle for various mixer sizes and types to match the appropriate scale, from benchtop microfluidic mixing for discovery to large-scale multi-inlet vortex and impingement jet mixers for clinical and GMP manufacturing contexts. However, formulating and benchmarking batches of LNPs, for each mixer under different mixing conditions, can be time- and materials- intensive, particularly at larger scales. Instead, using a pair of competitive chemical test reactions and kinetic modeling, we mapped the inherent micromixing times as a function of mixer geometry, total flow rates, and flow rate ratios. This mapping, shown to be consistent with relevant trends in LNP physicochemical characteristics, not only allowed us to facilely scale up and down among mixers without extensive experimentation, but also revealed fundamental timescales of particle formation in the microscale.