Preparation and characterization of polymer coated small unilamellar vesicles

Glucose oxidase was entrapped in small unilamellar vesicles composed of phosphatidylcholine, dicetyl phosphate and cholesterol. Prediction of the enzyme content of liposomes by calculations based on input concentrations of lipid and protein, dimensions of the lipids and the liposomes yielded one protein per vesicle. The entrapment efficiency was experimentally determined to be about 13%. On the other hand the entrapment efficiency for the small chromate ions was found to be significantly lower (0.1%). The liposomes were then coated with a polymer, poly(1,4-pyridinium diylethylene salt). It was possible to remove the lipoid material from underneath the polymer layer with various techniques. The effect of sonication and treatment with organic solvents (tested for this purpose) on enzyme activity were found to be very significant and Triton X-100 was chosen for this purpose. It was shown that the enzyme within the remaining net has 89% of its original activity.