SL01 is an ionizable cationic lipid compound pKa 6.31）developed by Seqirus, characterized by a biodegradable ester backbone and tertiary amine headgroup, enabling pH-dependent charge modulation. Its structure incorporates twin hydrophobic tails with unsaturated carbon chains, enhancing membrane fluidity and promoting endosomal escape. The lipid’s pKa (~6.5–7.0) optimizes nucleic acid complexation at physiological pH while minimizing cytotoxicity. SL01 demonstrates robust mRNA encapsulation efficiency (~90%) in lipid nanoparticles (LNPs) and facilitates intracellular delivery via endocytosis. Preclinical studies highlight its efficacy in inducing potent humoral and cellular immune responses, particularly in influenza mRNA vaccines. Its ester linkages ensure gradual metabolic clearance, reducing long-term toxicity. SL01-based LNPs exhibit stability in serum and compatibility with scalable manufacturing processes, making it a versatile candidate for therapeutic mRNA delivery.
