Tuning Targeted Liposome Avidity to Cells via Lipid Phase Separation.

The addition of both cell-targeting moieties and polyethylene glycol (PEG) to nanoparticle (NP) drug delivery systems is a standard approach to improve the biodistribution, specificity, and uptake of therapeutic cargo. The spatial presentation of these molecules affects avidity of the NP to target cells in part through an interplay between the local ligand concentration and the steric hindrance imposed by PEG molecules. Here, we show that lipid phase separation in nanoparticles can modulate liposome avidity by changing the proximity of PEG and targeting protein molecules on a nanoparticle surface. Using lipid-anchored nickel-nitrilotriacetic acid (Ni-NTA) as a model ligand, we demonstrate that the attachment of lipid anchored Ni-NTA and PEG molecules to distinct lipid domains in nanoparticles can enhance liposome binding to cancer cells by increasing ligand clustering and reducing steric hindrance. We then use this technique to enhance the binding of RGD-modified liposomes, which can bind to integrins overexpressed on many cancer cells. These results demonstrate the potential of lipid phase separation to modulate the spatial presentation of targeting and shielding molecules on lipid nanocarriers, offering a powerful tool to enhance the efficacy of NP drug delivery systems.