The EmulsiFlex range from Avestin uses extrusion to enhance liposome formation
8 Dec 2016
Avestin’s EmulsiFlex range of high-pressure homogenisers increases liposome reproducibility while decreasing the number of passes required to produce consistently sized liposomes.
A liposome is a spherical lipid vesicle made up of natural and/or synthetic phospholipids having at least one lipid bilayer. Liposomes, thanks to their biocompatibility, biodegradability, low toxicity, and ability to trap both hydrophilic and lipophilic compounds are of particular interest as vehicles for the administration of pharmaceutical drugs and nutrients. They also allow detailed analysis of protein-protein and protein-lipid interactions.
There are different types of liposomes including: small (20-100 nm) unilamellar liposome vesicles (SUVs), large (100-250 nm) unilamellar vesicles (LUVs) and 1-5 μm multilamellar vesicles (MLVs) that have several lamellar phase lipid bilayers.
Homogenous liposomes of defined size are desirable as they permit the analysis of the effect of membrane curvature, which is crucial in cell signalling, endocytosis, exocytosis, membrane fusion and protein trafficking Multivesicular liposomes are less useful for research and drug pharmaceutical applications, as both stability and drug dosage are hard to control and core volume can be small.
Forcing MLVs through polycarbonate filters with defined pore sizes tears them apart to create smaller fragments that can reform as more stable LUVs or SUVs with high encapsulation capacity. Increasing the number of extrusion passes results in a greater uniformity of liposomes and altering pore size can affect the
SUV/LUV ratios. Extrusion therefore offers distinct advantages over other liposome production techniques, such as sonication, freeze-thaw or sedimentation. All these approaches have drawbacks, particularly with regard to consistency and efficiency of liposome preparation with highly curved surfaces (i.e. diameter <100nm). And although reverse phase evaporation and detergent dialysis can produce LUVs, lipid solubility and removal of detergent can be problematical.
The EmulsiFlex range of high-pressure homogenisers from Avestin allows operators to perform both extrusion and homogenisation of liposomes in solution, increasing reproducibility while reducing the number of extrusion passes required.
This expertise isn’t limited to benchtop homogenisation/extrusion systems either. Pilot and production scale options are also available, so whatever level of liposome manufacturing you may be considering Biopharma’s Avestin equipment range can provide what you need. To read the full piece on their blog click here.