Liposome Preparation by a New High Pressure Homogenizer Gaulin Micron Lab 40

Abstract

High pressure expansion of lipid dispersions with a lab-scale homogenizer (Gaulin Micron LAB 4 0) was tested to produce forced lecithin hydration and subsequent liposome formation. A single-step liposome preparation method was developed. Lipid composition, pressure and the number of passages as the main process parameters were varied. Homogenizing with the new apparatus leads to small unilamellar vesicles (SUV), when 10% (w/w) lipid dispersions are used. Depending on the lipid composition the resulting vesicles ly from 25 up to 50 nm and show quite narrow particle size distribution. The cumulation of SUVs at their theoretical low size limits was detected after negative staining by transmission electron microscopy. Cryo-electron microscopy (CEM) of very thin vitrified layers of unfixed and unstained dispersions of vesicles confirmed in principle the negative staining data. Erosions of the especially stressed parts of the homogenizer, the valve, were monitored by scanning electron microscopy (SEM). They turned out, to be low, and this is particularly important for parenteral administration.