Liposomes can be classified by their size and lamellarity. These characteristics, along with lipid composition, determine the liposomes' stability and encapsulation efficiency.

Multilamellar vesicles (MLVs) are relatively unstable, and they are not effective drug carriers due to their small core volume. This can be addressed by performing extrusion, 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. These fragments 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 and retain high encapsulation capacity.

Additional passes through the membrane may further reduce the particle size and narrow the 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. 

LUVs may be the desired product of extrusion, as they have high encapsulation efficiency due to their large core volume. Producing these, rather than SUVs, can be achieved simply by 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
Comparison of three liposome preparation methods
 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
Application pharmaceuticals, Lab research Production, Food, Cosmetics, nutrient pharmaceutical production
Equipment Hand Liposome Extruder
Jacketed Liposome Extruder
Online Liposome Extruder
NanoGenizer; PilotGenizer  HandGenzier+Extruders