Lipid C16-C is an ionizable cationic lipid utilized in creating lipid nanoparticles (LNPs) for mRNA delivery both in vitro and in vivo. LNPs with lipid C16-C are preferentially directed to the liver and spleen in mice over other organs such as the lungs, kidneys, lymph nodes, and heart. These LNPs, when encapsulating mRNA for HER2-targeting chimeric antigen receptor (CAR), prompt CAR expression in human macrophages ex vivo and have shown to induce cytotoxic effects in HER2-expressing SKOV3 ovarian cancer cells in vitro.