Previous work has shown that ionizable lipids with branching tails increases the efficiency of mRNA delivery by LNPs. However, two major issues have prevented a systematic analysis of the effect of branching ionizable lipids. First, tail branching leads to an enormous diversity of chemicals; second, the number of commercially available branching ionizable lipids is limited.
To overcome these hurdles, the researchers generated a systematic lipid library of branching ionizable lipids, and limited this library to a specific subset of branching lipids which could be described with just two parameters: total carbon number and symmetry. They then tested the 32 lipids in this library for their effect on the stability of LNPs containing mRNA (LNP-RNA).