Liposomes
These are systems in which lipids are added to an aqueous buffer to form vesicles, structures that enclose a volume much like a balloon. The wall or skin of the balloon is made up of a lipid bilayer (two molecules thick of an ordered sheet of these lipid molecules) with the inside volume of liquid different from or the same as the continuous phase. The chemical nature of the lipids and the lipid concentration in water dictates whether or not vesicles will be formed.
Most often used in the Pharmaceutical, Food and Personal Care/Cosmetics industries, liposomes are used to carry drugs, peptides, proteins, vitamins, and other actives to specific target destinations (organs). Before Microfluidizer® processors were available, the only way to make liposomes was with equipment like rotor-stator mixers. These mixers are incapable of the tight particle distribution, and particle size reduction that can be achieved with a Microfluidizer® processor. Therefore, many products were not scalable to production volumes. However, with Microfluidics high-shear processors, customers can easily achieve particle sizes less than 100 nanometers, providing narrow size distribution and increased stability.
Lipids are sensitive to temperature in a different way from oil/water emulsions. Most ordered microstructures, such as the lipids forming the bilayer wall of a liposome vesicle, have a transition temperature at which they become fluid. Caution must be exercised to prevent too much heat causing degradation of the lipids, resulting in undesirable by-products. Since most lipids are derived from mammals, a good rule is to keep lipids at or slightly above body temperature. Warming the batch prior to processing, running several passes with controlled cooling, and maximum cooling on the final pass are recommended. Cooling options are available on all Microfluidizer processors.
Liposomes have similarities to oil/water emulsions. Like emulsions, there are separate physical structures that are fluid. When processing liposomes with a Microfluidizer processor, the higher the pressure, the more energy imparted, the smaller they get; and with more passes, the more uniform they get.
In general, the important guidelines for processing Liposomes are:
Microfluidizer processors are guaranteed to scaleup from laboratory to production processes.
Below is a liposomal sample that was processed in our laboratory.
Home
ProcessorsNewsSeminarsCustomer SupportRepresentativesEmploymentContact Us
Copyright © 2004-2006 MFIC Corporation. All rights reserved. Microfluidizer® is a registered trademark of Microfluidics.
