(605f) A 3D-Printed Microfluidic Device for High-Throughput Production of mRNA-Lipid Nanoparticles

Lipid nanoparticles (LNPs) play a vital role in drug delivery as seen in the recent life-saving messenger RNA (mRNA) vaccines against coronavirus disease 2019 (COVID-19), mRNA-1273 and BNT162b. The entrapment of mRNA is accomplished during particle formation, when the cationic lipids interact with anionic mRNA. Production of LNPs via microfluidic hydrodynamic focusing has been thoroughly investigated, where a focused stream of lipids is generated by two sheathing streams of aqueous buffer containing the mRNA. LNPs are formed as the lipids are rapidly mixed with the aqueous buffer. Microfluidic hydrodynamic focusing is a popular LNP production technique due to its unique advantages: 1) continuous-flow production, 2) controllable and tunable particle size, and 3) single-step fabrication. Despite its success, current microfluidic hydrodynamic focusing devices are fabricated by elastomer molding, which is an expensive and laborious device fabrication technique. The resulting devices often have poor user interfaces, are prone to clog due to the small channels, and are made of delicate materials that can only be used at low flow rates (µL/min range) which greatly limits the production throughput. To address these issues, we redesigned the hydrodynamic focusing devices by replacing the original planar channels with three-dimensional flow paths. By stereolithography printing, we fabricated a microfluidic device that is made of durable methacrylate-based materials and implements readily adaptable interfaces by commercial fluidic connectors. We demonstrated encapsulation of 4knt mRNA and characterized the resulting LNPs. With larger microchannels than conventional microfluidics, our 3D-printed microfluidic device can be used at higher flow rates (mL/min range), potentially increasing LNP production throughput by > 30-fold.