TLC—A rapid method for liposome characterization

Abstract

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 liquid medium in which they are introduced (blood plasma for in vivo studies and the saline buffer solution for in vitro studies). Using thin-layer chromatography (TLC) we compared the behaviour of phosphatidylcholine (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% O2 + 5% CO2). All variants contained the same amount of phosphatidylcholine. Thin-layer chromatography was performed on silica gel 60 as adsorbent. 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/alcohol/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 using 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.

Controlling Liposomal Drug Release with Low Frequency Ultrasound: Mechanism and Feasibility

“…The lipids of the liposomal dispersions before and after ultrasonic irradiation were extracted by the Bligh and Dyer procedure and analyzed by TLC (silica gel 60, Merck, Darmstadt, Germany), which was developed using a solvent system of chloroform/methanol/water (65:25:4 by volume). Spot detection was performed by spraying the plates with 1.6 M copper sulfate (Sigma) in 6.8% phosphoric acid, v/v (BioLab, Jerusalem, Israel), and then drying the plates with warm air. − …”

Thin layer chromatography as a simple and quick in-process tool for qualitative and semi-quantitative determination of unentrapped drugs in liposomal formulations

“…However, in case of Amphotericin B, the minimum level of detection was higher (20%) compared to the other two. The overall data shows that the detection of the free drugs is dependent on a various aspects such as the type of drug, intraction with stationary silica phase, liposome size, the radial migration rate, liposomal pH, polarity of intracting components and most importantly the mode of visualization [22,23,25,28]. 3; C1 to C6 denote free drug concentrations (range of 0.5 to 10 μg/ml) (b) Spots E1 -E6 denote increasing order of entrapped drug concentrations (range of 0.5 to 10 μg/ml) and (c) Spots J1 to J6 denote spiked free drug sample preparations with an increasing proportion of free drug (range 5 to 100 %) at the total drug concentration 10 μg/ml.…”

“…There has been a report utilizing TLC for evaluating modification of the different types of phosphatidylcholine liposomal vesicles e.g. multilamellar liposomes (MLV); small unilamellar vesicles (SUV); and reverse phase evaporation vesicles (REV), before and after storage for 15 min in Krebs-Henseleit solution [22]. A significant difference in migration pattern was observed in all type of vesicles with the optimized mobile phase.…”

TLC Characterization of Liposomes Containing Angiotensinogen, Angiotensine I, Angiotensine II and Saralazin

“…The liposomes used in these physiological studies were prepared from egg phosphatidylcholine (type X-E; Sigma), 60 mg lipid per mL of solution being incorporated, according to the method described by Bangham et al (1965), and modified by us (Brailoiu et al, 1994).…”

“…The liposomes for TLC studies were prepared from egg phosphatidylcholine type X-E (30 mg lipid per mL aqueous phase represented by triple-distilled water) (Sigma, St. Louis, MO, USA) according to the method described by Bangham et al (1965) and modified by us (Brailoiu et al, 1994) as follows. Diethyl-ether was added to the suspension of multilamellar vesicles in a 1:10 volume ratio.…”