IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Biomaterials Wednesday Sessions
       Session BI+SS-WeM

Paper BI+SS-WeM6
Surface-bound Liposomes for Biomedical Applications

Wednesday, October 31, 2001, 10:00 am, Room 102

Session: Biological Interface & Surface Science
Presenter: H.J. Griesser, CSIRO, Australia
Authors: P. Vermette, CSIRO, Australia
E. Gagnon, Universite Laval, Canada
L. Meagher, CSIRO, Australia
D. Dunstan, Melbourne University, Australia
H.J. Griesser, CSIRO, Australia
C. Doillon, Universite Laval, Canada
Correspondent: Click to Email
Injectable liposomes, in particular PEG-coated liposomes, are well known in the pharmaceutical industry for drug delivery. However, much of the drug never reaches the intended target site. We have developed methods for binding liposomes onto surfaces of biomedical devices for controlled local delivery of drugs adjacent to implanted biomedical devices. In this way we aim to reduce drug amounts and wastage, and control the local host response to the implant, a response which with most current biomaterials typically is dominated by fibrous tissue encapsulation. We have produced liposomes with encapsulated drugs and model substances, characterized them in terms of size and release performance, and bound them onto polymeric surfaces. PEGylated phospholipid liposomes were produced by extrusion through polycarbonate membranes of various pore sizes. The diameters of the liposomes were characterized by photon correlation spectroscopy. For binding liposomes, polymer surfaces were coated with streptavidin, which was used for affinity capture of biotinylated PEGylated liposomes. Streptavidin was covalently bound onto polymer surfaces via an amine plasma (glow discharge) polymer interlayer and a layer of polyacrylic acid, onto whose carboxylate groups the streptavidin was attached by carbodiimide chemistry. Detailed surface analyses were used to characterize and verify each step in the fabrication of the liposome coated surfaces. To test the in vivo efficacy of liposome coated biomaterials, an angiogenesis promoting drug was encapsulated and the liposomes attached. Both in vitro and in vivo there occurred markedly enhanced angiogenesis. Another way of using the same concept may be to implant streptavidin coated biomedical implants and then inject drug-loaded liposomes. Experiments are currently underway to investigate whether circulating biotinylated liposomes can thus be enriched at an implant surface by affinity capture with surface-immobilized streptavidin.