Liposome
Liposomes can be classed via their size and lamellarity, as shown in Figure 1. It is these characteristics, along with lipid composition that determine the stability and encapsulation efficiency.

Liposome
 
Figure 1. Classification of liposomes based on size and lamellarity.

 

Multilamellar vesicles (MLVs) are relatively unstable, and are not effective drug carriers due to the small core volume. Extrusion may be performed, whereby the MLVs are forced through polycarbonate filters with defined pore sizes. This disrupts the lipid bilayers of the vesicles, and if the force is strong enough, the MLV is completely torn apart, creating smaller fragments, which immediately form as small unilamellar vesicles (SUVs) or large unilamellar vesicles (LUVs) at the other side of the membrane, with a diameter reflecting the pore size. The resulting unilamellar vesicles are more stable, retaining high encapsulation capacity.

By performing a number of passes through the membrane, a particle size may further reduce, along with a narrower particle size distribution, as shown in Figure 2 (below).
 


Liposome Extrusion Membrane
 
Liposome Membrane with 100nm Pore Size

Liposome Extrusion Mechanism
 
Schematic representation of the extrusion process.

Liposome Extrusion Size Distribution
 
Graph reflecting uniformity of size via repeated passages of the liposomes through the membrane.
 
Figure 2. Forming unilamellar liposomes of the defined size by extrusion through a defined pore membrane filter. 
 

 

In addition, LUVs may be the desired product of extrusion, as they also show high encapsulation efficiency due to its large core volume. Producing these rather than SUVs would simply be a case of increasing the filter pore sizes in the extruder membranes.

Liposome HandExtruder Jacketed Liposome Extruder Lab, Pilot 2mL-3000mL Online Liposome Extruder
Hand Liposome Extruder 
Lab 0.5mL-2mL
Jacketed Liposome Extruder
Lab, Pilot 2mL-3000mL
Online Liposome Extruder
Lab, Pilot, Production 2mL-100L
Hand Drive   Compressed Gas High Pressure Homogenizer or Pump
 

Comparation of three Methods for Preparation of the Liposome
 
 Methods     Liposome Extruder  High Pressure Homogenizer High Pressure Homogenizer
and Liposome Extruder
Speed Slow Quick Quick
Capacity 0.5mL-100L 10mL-1000L 10mL-100L
Size Uniform Size, as small as 50nm Gaussian distribution, large than 180nm Uniform Size, as small as 50nm
Appication pharmaceuticals, Lab research Production, Food, Cosmetics, nutrient pharmaceutical production
Equipment Hand Liposome Extruder
Jacketed Liposome Extruder
Online Liposome Extruder
NanoGenizer; PilotGenizer  HandGenzier+Extruders
Nanogenize+Extruders
PilotGenizer+Extruders