Polymers, Nanoparticles and Phospholipids

Abstract

In addition, we find binding of charged nanoparticles to the outer surface of phospholipid liposomes produces particle-stabilized liposomes that repel one another and do not fuse. Subsequently, the volume fraction can be raised as high as ∼50%, reversibly, still without fusion. In studies of liposome longevity, we verify the stability of particle-stabilized liposome suspensions with volume fraction up to 16% for up to 50 days, the longest period investigated. In contrast to the stabilized liposomes, the volume fraction of the same liposomes without nanoparticles is typically less than ∼2% with a longevity of 4∼5 days. Fluorescent dyes are encapsulated within the particle-stabilized liposomes, without leakage. Although these particle-stabilized liposomes are stable against fusion, ∼75% of the outer liposome surface remains unoccupied, which is still biofunctionalizable tested with ligand-receptor binding. This work not only provides a robust nanoparticle-liposome complex system which possesses many potential biomedical and biotechnological applications, but also offers new understanding and scholarship on the physical and biological characteristics of phospholipid liposomes such as membrane stability, permeability, rigidity, and biofunctionality. It also generates a new brand of colloids, which are soft, hollow and functionalizable compared with the conventional hard spheres.