306-O12B (Triscormin)

306-O12B is a cationic lipidoid.306-O12B LNP is more efficient than MC-3 LNP in inducing loss-of-function mutations in Angptl3 through CRISPR-Cas9-based genome editing. It has been used in the generation of lipid nanoparticles (LNPs). Intravenous administration of LNPs containing 306-O12B and encapsulating an mRNA reporter accumulate specifically in the mouse liver. LNPs containing 306-O12B and encapsulating mRNA encoding the Cas9 nuclease (mCas9) and single-guide RNA targeting Angptl3 (sgAngptl3), the gene encoding angiopoietin-related protein 3, have been used to induce CRISPR-mediated gene knockdown in mice resulting in a reduction of serum Angptl3 protein, LDL, and triglyceride levels. A novel ionizable lipids library was constructed by a combinatory solvent-free Michael addition reaction between disulfide bondincorporated acrylate lipid tails and amine-containing heads. In this library, the tail-branched bioreducible ionizable lipid 306-O12B was screened out. Due to the presence of special ester bonds and branches in lipid tails, the accumulation of iLNPs in the liver was increased, and endosome escape was prompted. These iLNPs were used to deliver CRISPR-Cas9 mRNA and sgRNA targeting to angiopoietin-like 3 (Angptl3). Compared with FDA-approved MC3, 306-O12B induced more specific and efficient Angptl3 gene knockout in the liver, resulting in significant decrease in the levels of serum Angptl3 protein, low-density lipoprotein cholesterol (LDL-C), and triglyceride. According to the molecular shape hypothesis outlined several decades ago, the increase of branches can create ionizable lipids with more cone-shaped structure to enhance the destructiveness of the membrane structure of the endosome and increase mRNA release. However, it is unknown whether the structural stability of iLNPs will be sacrificed with the increase of branches. The optimal branches and chain length need to be further explored.