Millisecond Rapid Mixing Stopped-Flow BioSAXS Study Comparing the mRNA and Ribonucleoprotein Loading Mechanism in BioNTech/Pfizer and Modern

The interaction kinetics of lipid nanoparticle (LNP) with its payloads such as proteins and mRNAs controls product stability, loading and release efficiency, as well as efficacy after administered in the biological system. We still have very limited understanding of interactions between charged LNPs and the gene-editing therapeutic candidates such as mRNAs and RNPs. The aim of the proposal is to investigate the structural dynamics of LNPs upon mRNAs and ribonucleoprotein (RNPs) loading on a millisecond time scale using the rapid mixing stopped-flow BioSAXS facility at the ID02 beamline. Steady state SAXS experiment has shown that the ionisable ALC-0315 lipid can form lyotropic liquid crystalline cubic and hexagonal mesophases which are responsive to pH. We will investigate how model mRNAs and RNPs drive nanostructural changes of cationic LNPs, including the BioNTech/Pfizer COVID-19 Vaccine LNPs (ALC-0315 and ALC-0159), and the Moderna COVID-19 Vaccine LNPs (SM-102 and PEG-DMG).