Enhancement of target toxin neutralization effect in vivo by PEGylation of multifunctionalized lipid nanoparticles

Abstract

Protein–protein (e.g., antibody–antigen) interactions comprise multiple weak interactions. We have previously reported that lipid nanoparticles (LNPs) bind to and neutralize target toxic peptides after multifunctionalization of the LNP surface (MF-LNPs) with amino acid derivatives that induce weak interactions; however, the MF-LNPs aggregated after target capture and showed short blood circulation times. Here we optimized polyethylene glycol (PEG)-modified MF-LNPs (PEG-MF-LNPs) to inhibit the aggregation and increase the blood circulation time. Melittin was used as a target toxin, and MF-LNPs were prepared with negatively charged, hydrophobic, and neutral amino-acid-derivative-conjugated functional lipids. In this study, MF-LNPs modified with only PEG5k (PEG5k-MF-LNPs) and with both PEG5k and PEG2k (PEGmix-MF-LNPs) were prepared, where PEG5k and PEG2k represent PEG with a molecular weight of 5000 and 2000, respectively. PEGylation of the MF-LNPs did not decrease the melittin neutralization ability of nonPEGylated MF-LNPs, as tested by hemolysis assay. The PEGmix-MF-LNPs showed better blood circulation characteristics than the PEG5k-MF-LNPs. Although the nonPEGylated MF-LNPs immediately aggregated when mixed with melittin, the PEGmix-MF-LNPs did not aggregate. The PEGmix-MF-LNPs dramatically increased the survival rate of melittin-treated mice, whereas the nonPEGylated MF-LNPs increased slightly. These results provide a fundamental strategy to improve the in vivo toxin neutralization ability of MF-LNPs.