LIPID A6

Ionizable lipid A6 (di(dec-3-yn-1-yl) 9-((4-(dimethylamino) butanoyl)oxy) heptadecanedioate) was developed by modifyingthe backbone structure of Dlin-MC3-DMA through introducing alkynyl and ester groups into the lipid tails. Alkyne lipid A6 demonstrated a significant improvement in transfection efficiency (~8.5, ~2.0, and ~2.5-fold higher than the original MC3, C12-200 and cKK-E12 containing LNPs, respectively).The performanceof the A6 coprepared into iLNPs with other amine-containinglipid materials (cKKE12) was evaluated, and the molar ratio ofthe formulation was changed to 35:16.0:46.5:2.5 (A6/cKKE12:DOPE: Chol: PEG). The results showed that these formulationssynergistically facilitated more effective mRNA delivery andimproved tolerability following single and repeated dosing. Itwas confirmed that albumin-associated macrophage phagocytosisand endocytosis is an apolipoprotein-independent cellularinternalization pathway of iLNPs in the liver.According to the fusion kinetics, the lipids with highfrequencytail protrusion and high lateral diffusion coefficientcan perturb and trigger membrane sprouting, which in turn promotesmembrane fusion. The application of iLNPs with thoselipids (such as A6) may be an effective method to further enhancethe release of mRNA in vivo.