Lipid Nanoparticles Formulated with a Molecular Hybridization-Derived Ionizable Lipid Enabled OVA-mRNA Delivery for Melanoma Prevention in Mice

Lipid nanoparticles (LNPs) have emerged as a powerful platform for mRNA vaccine delivery, with ionizable lipids playing a pivotal role in enhancing cellular uptake and endosomal escape, thereby improving therapeutic efficacy. In this study, we designed and synthesized 12 novel ionizable lipids via molecular hybridization, incorporating a hydroxyalkylamine headgroup, an ester linkage, and a cis -double bond tail. These lipids were then formulated into LNPs with helper lipids and eGFP or LUC mRNA. Through cell transfection and in vivo imaging experiments, the O2–N5–OLE LNP was identified with superior mRNA delivery capabilities, particularly in immune cells. Subsequently, it was employed to encapsulate the tumor model antigen ovalbumin (OVA) mRNA vaccine, and its preventive effects against mouse melanoma were evaluated. The results demonstrated that O2–N5–OLE LNP@OVA mRNA exhibits superior tumor suppression. Additionally, the OVA mRNA delivered by O2–N5–OLE LNP significantly elevated serum OVA-IgG and IFN-γ levels and activated dendritic cells and CD8 + T lymphocytes, indicating that the vaccine effectively activated both humoral and cellular immunity. Coupled with the excellent biocompatibility of the O2–N5–OLE LNP, these findings highlight its remarkable delivery efficacy and provide a strong experimental foundation for its potential clinical application.