Membrane stabilization and transformation in organoclay-vesicle hybrid constructs

We describe the preparation, characterization and properties of a novel inorganic-organic hybrid construct based on the incarceration of individual unilamellar vesicles of 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPG) within an ultrathin shell of polycationic organoclay oligomers. Unlike uncoated vesicles, the organoclay-vesicle nanocomposites show no temperature-dependent changes in size, and exhibit a 12 degrees C increase in the bilayer melting transition temperature (T(m)) due to charge neutralization at the membrane surface. Vesicles coated below Tm, show minimal reversibility in the transition from the L(beta) to L(alpha) state, whilst constructs produced in the bilayer fluid state demonstrate full reversibility for samples prepared with ultrathin organoclay shells. Release studies indicate that the organoclay-vesicle membranes show a similar permeability to entrapped ibuprofen as uncoated vesicles, suggesting that the constructs could be functionally effective under adverse conditions.