PH SENSITIVE LIPOSOME COMPOSITIONS FOR CONTROLLING SURFACE TOPOGRAPHY AND BINDING REACTIVITY IN FUNCTIONALIZED LIPOSOMES

摘要

Methods for controlling surface topography and binding reactivity in functionalized lipid layers, including in the form of liposomes, using pH-dependent processes. During direct cell-to-cell communication, lipids on the extracellular side of plasma membranes reorganize, and membrane associated communication-related molecules co-localize. At co-localization sites, sometimes identified as rafts, the local cell surface topography and reactivity are altered. Integration of these processes on nanometer-sized lipid vesicles used as drug delivery carriers would precisely control their interactions with diseased cells minimizing toxicities. Included are pH-dependent processes on functionalized lipid bilayers demonstrating reversible sharp changes in binding reactivity within a narrow pH window. Cholesterol enables tuning of the membrane reorganization to occur at pH values not necessarily close to the reported pKa's of the constituent titratable lipids. One illustrative function of the invention is to use liposomes to deliver bioactive agents to cancer or tumor cells and compositions of specific lipids that form liposomes to deliver a biologically active agent.