(260c) Liposomes Stabilized by Bilayer Conjugation to a Hydrogel Core

Liposomes are spherical lipid bilayer constructs with diameters in the range of tens to hundreds of nanometers. They have become essential tools for characterizing cell membrane properties and presenting membrane proteins for biochemical analysis, and they have found widespread application in drug delivery. Their applications are hindered, however, by their inherent instability and short shelf-life and by the relative complexity of liposome fabrication techniques.

We have developed a new class of hybrid polymer-lipid liposomes in which vinyl-modified lipids are covalently conjugated to a hydrogel matrix at the liposome core. These bilayer-anchored liposome nanogels demonstrate superior stability relative to standard liposomes and provide a nanoscale surface-modified template for simple and rapid assembly of membranes with varying compositions.

To generate a hydrogel-anchored lipid species, phosphatidylethanolamine lipids were modified with a short-chain poly(ethylene glycol) (PEG)-acrylate moeity. These lipids were then used to fabricate liposomes according to standard protocols. The liposomes encapsulated a hydrogel precursor solution consisting of PEG-diacrylate molecules and a free radical photoinitiator. Upon initiation of hydrogel polymerization, the acrylate-modified lipids were incorporated into the polymer chains. The product nanogel liposomes were characterized by size-exclusion chromotography, dynamic light scattering, and cryo-transmission electron microscopy.