Construction of Spleen-Accumulated Polysorbate 20-Containing Ionizable Lipid Nanoparticles for mRNA Delivery.

Messenger RNA therapy represents a transformative therapeutic in vaccine development, tumor immunotherapy, and genetic disease intervention. Polyethylene glycol (PEG) lipid, a key component of ionizable lipid nanoparticles (iLNPs) for mRNA delivery, and the PEG antibodies induced by PEG are associated with hypersensitivity and accelerated blood clearance. To address the above PEG-associated challenges, we systematically investigated polysorbate 20 (PS20) as an alternative for constructing PEG-free iLNPs. The formulation of PS20-incorporated iLNPs (PS20-iLNPs) for carrying mRNA was systematically investigated by analyzing the particle size, pKa, endosomal escape efficiency, and cellular internalization efficiency of iLNPs with different molar ratio PS20 content (0.5-5.0%). iLNPs with a relative molar ratio of 2.5% were identified as the optimal mRNA delivery carrier. This carrier exhibited excellent resistance to serum protein adsorption capacity, with serum stability 1.3-fold higher than PEG-iLNPs. At high lipid concentrations (2.7 mg/mL), the cell viability of PS20-iLNPs was maintained at 91.1%, which was 1.07-fold higher than PEG-iLNPs. Under serum interference, PS20-iLNPs achieved a transfection efficiency of 46.5%, marking a 10.6% improvement over PEG-iLNPs under identical conditions. Notably, PS20-iLNPs exhibited 24 times higher spleen accumulation than PEG-iLNPs. These findings highlight PS20 as a viable PEG substitute for developing PEG-free spleen-accumulated mRNA delivery platforms with enhanced therapeutic potential.