Liposome retention in size exclusion chromatography.
BACKGROUND
Size exclusion chromatography is the method of choice for separating free from liposome-encapsulated molecules. However, if the column is not presaturated with lipids this type of chromatography causes a significant loss of lipid material. To date, the mechanism of lipid retention is poorly understood. It has been speculated that lipid binds to the column material or the entire liposome is entrapped inside the void.


RESULTS
Here we show that intact liposomes and their contents are retained in the exclusion gel. Retention depends on the pore size, the smaller the pores, the higher the retention. Retained liposomes are not tightly fixed to the beads and are slowly released from the gels upon direct or inverted eluent flow, long washing steps or column repacking. Further addition of free liposomes leads to the elution of part of the gel-trapped liposomes, showing that the retention is transitory. Trapping reversibility should be related to a mechanism of partitioning of the liposomes between the stationary phase, water-swelled polymeric gel, and the mobile aqueous phase.


CONCLUSIONS
Retention of liposomes by size exclusion gels is a dynamic and reversible process, which should be accounted for to control lipid loss and sample contamination during chromatography.
Ruysschaert
Tristan
T
Groupe de biotechnologie des protéines, Institut de Pharmacologie et de Biologie Structurale, F-31077, Toulouse, France. tristan.ruysschaert@ipbs.fr
Marque
Audrey
A
Duteyrat
Jean-Luc
JL
Lesieur
Sylviane
S
Winterhalter
Mathias
M
Fournier
Didier
D
D000110:Acetylcholinesterase / Q000737:chemistry; D000818:Animals; D001709:Biotechnology / Q000379:methods*; D002627:Chemistry, Physical / Q000379:methods; D002845:Chromatography / Q000379:methods*; D002850:Chromatography, Gel / Q000379:methods; D004331:Drosophila melanogaster / Q000201:enzymology; D004337:Drug Carriers / Q000737:chemistry; D005452:Fluoresceins / Q000737:chemistry; D005782:Gels / Q000737:chemistry; D007700:Kinetics; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D010539:Permeability
D004337:Drug Carriers; D005452:Fluoresceins; D005782:Gels; D008055:Lipids; D008081:Liposomes; D008567:Membranes, Artificial; D000110:Acetylcholinesterase; C007740:fluorexon