Abstract

Poly(ethylene glycol) (PEG)-lipids endow lipid nanoparticles (LNPs) with colloidal stability but elicit anti-PEG immunity upon repeat dosing. Here it is replaced PEG-lipids with microbial rhamnolipids (RLs) to create PEG-free, self-adjuvanting LNPs. RL-LNPs show higher than 90% mRNA encapsulation and enhanced dendritic cell uptake via the mannose receptor and DEC205, redirecting expression to lymph nodes after intramuscular injection. Compared with size-matched PEG-LNPs, RL-LNPs enhance transfection and neutralizing capacity against pseudoviruses, while potently amplifying Th1-biased humoral and cytotoxic T-cell responses. Quantitative proteomics and western blotting reveal activation of the C-type lectin receptor (CLR)/NF-κB axis, corroborating intrinsic adjuvancy. Notably, RL-LNPs avoid PEG-associated mast-cell infiltration under repeat dosing while maintaining favorable systemic chemistry panels and histology. These data establish glycolipids as dual-function substitutes for PEG-lipids, coupling stabilization with receptor-programmed immunity for next-generation mRNA vaccines.