With rich experience in liposome research and development, Creative Biostructure offers world-leading liposomal products and services to customers by applying our comprehensive Mempro™ Liposome Technology in various fields. Lipid content analysis is an important service supported by Mempro™ Liposome Analysis.
Figure 1. Bending moduli of different liposomes prepared by a variety of lipids. Three thermodynamic phase states of the liposomes were separated by dotted lines. A schematic illustration of phase-dependent liposome membrane rigidity is shown below. (Y. Takechi-Haraya, et al., 2016)
Lipid content exerts great influence on the characteristics of liposomes produced from a specific lipid fraction. There are a series of methods that can be used to measure the lipid content of a fraction in order to identify the classes of lipid or calculate the total amount of lipid material presented.
The measurement of the lipid concentration of a liposome sample is generally performed by the measurement of phosphorous content since the most of the lipid classes to form liposomes contain an equal amount of phosphorus. Phosphorous content is usually measured by using molybdate-containing reagents that yield a product with blue-color.
A method that known as the Bartlett assay measures the absorbance of an acid-digested phosphate at 830 nm. Lipids can also be analyzed by the absorbance measurement of complex formed of lipids and ammonium ferrothiocyante at 488 nm. 31P-NMR can be applied in determination of total amount of phosphorus as well.
High performance liquid chromatography (HPLC):
It is very accurate in quantitative measurements of the phosphatidyl choline (PC) levels, which provide higher resolution for the minor components. Whereas, UV range of HPLC analysis of lipid is limited from 200 nm to 210 nm because of the lack of chomophores in lipid structure.
Thin layer chromatography (TLC):
TLC shows great potentials to efficiently separate and quantify the lipids in liposome samples. A mixture of chloroform, methanol and water is used as a mobile phase in TLC methods to faciliate the determination of lipid. To detect the phosphate and primary amino groups, molybdenum blue in sulphuric acid and ninhydrin stains were used.
NMR is also used to quantify the specific kind of lipid present in a liposome sample. Different lipids give their signals with slight differences since each particular lipid molecule will result in a specific resonance frequency of phosphorus. Quantitative results can be subsequently achieved by comparison of the resonance frequency.
Besides lipid content analysis, Creative Biostructure also offers a variety of liposome analysis services shown in related sections to meet your custom requirements. Please feel free to contact us for a detailed quote.
Y. Takechi-Haraya, et al. (2016). Atomic Force Microscopic Analysis of the Effect of Lipid Composition on Liposome Membrane Rigidity. Langmuir, 32: 6074-6082.
L. H. Klausen, et al. (2016). Mapping surface charge density of lipid bilayers by quantitative surface conductivity microscopy. Nature Communications, 7: 12447.
H. Kobayashi, et al. (2003). Comparative study of the product components of lipid oxidation in aqueous and organic systems. Chemistry and Physics of Lipids, 126: 111-120.