ALC-0315 is a synthetic ionizable lipid, designed specifically for use in lipid nanoparticle (LNP) formulations. It plays a pivotal role in the delivery of nucleic acids, particularly messenger RNA (mRNA), by forming stable complexes that protect the fragile genetic material from enzymatic degradation. ALC-0315 is a tertiary amine that becomes protonated under acidic conditions, such as those found in endosomes, which facilitates the release of mRNA into the cytoplasm after cellular uptake. This property makes it exceptionally effective in promoting intracellular delivery and expression of therapeutic genes.

In medicine and biotechnology, ALC-0315 has gained prominence as a key component of mRNA-based vaccines, most notably in the Pfizer-BioNTech COVID-19 vaccine. Within the LNP system, ALC-0315 works synergistically with other lipids to encapsulate and stabilize mRNA, ensuring efficient transport into antigen-presenting cells.