Morphological observations on liposomes bearing covalently bound protein: Studies with freeze-fracture and cryoelectron microscopy and small angle x-ray scattering techniques

The appearance of protein bound to the surface of intact and microfluidized liposomes and its possible influence on their morphology was examined by freeze-fracture electron microscopy, cryo electron microscopy and small angle X-ray scattering (SAXS) techniques. Results obtained by the two microscopy techniques were in agreement with one another in terms of vesicle size and localization of protein (tetanus toroid or immunoglobulin G) on the surface of vesicles. Surface-bound protein was observed as particles (10-12 nm diameter) by freeze-fracture electron microscopy and was confirmed by immunogold cryo microscopy. SAXS was shown to be a suitable means to further characterize liposomes with, or without bound protein. (C) 1998 Elsevier Science B.V.