Lipid N2-3L is an ionizable cationic lipid with a pKa of 8.99, utilized in the formation of supramolecular lipid nanoparticles (SMLNPs) for enclosing mRNA in both in vitro and in vivo applications. Lipid N2-3L-containing SMLNPs accumulate at the injection site and draining lymph nodes in mice, featuring a luciferase reporter gene. Additionally, SMLNPs made with Lipid N2-3L that encapsulate ovalbumin mRNA and the Toll-like receptor 7/8 (TLR7/8) agonist R-848 serve as adjuvants. These enhance dendritic cell maturation and antigen presentation, reducing tumor volume and increasing survival rates in MC-38-OVA colon cancer mouse models.