TLC - A RAPID METHOD FOR LIPOSOME CHARACTERIZATION

One of the most important problems for the use of liposomes as a drug delivery system is the modification of the vesicle induced by the liqu id medium in which they are introduced (blood plasma for in vivo studi es and the saline buffer solution for in vitro studies). Using thin-la yer chromatography (TLC) we compared the behaviour of phosphatidylchol ine (used for liposomes preparation) to that of the following unfilled liposomes: multilamellar liposomes (MLV); small unilamellar vesicles (SUV); and reverse phase evaporation vesicles (REV), before and after storage for 15 min in Krebs-Henseleit solution (37 degrees C, pH 7.4, aerated continuously with 95% O-2+5% CO,). All variants contained the same amount of phosphatidylcholine.Thin-layer chromatography was perfo rmed on silica gel 60 as adsorbant. Two types of solvents were tested: one based on chloroform/alcohol (n-butanol or n-propanol or methanol) /water mixture (in different ratios) and another based on alcohol/alco hol/water mixture (n-butanol/n-propanol/water in 4/3/3 volume ratio). In all variants of chloroform containing solvents no differences were found between phosphatidylcholine and all types of liposomes. When usi ng as solvent n-butanol/n-propanol/water significant differences were found between all types of liposomes before and after storage in Krebs -Henseleit solution. Their presence, after TLC treatment, was shown in electron microscopy studies.