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Figure 1. Lamellarity analysis of liposomes prepared by different methods. The liposomes with intensities that are below the lowest dashed line were characterized to be unilamellar, while the liposomes with intensities that are between the two lowest dashed lines were characterized to be bilamellar, and so on (A & C); A schematic diagram of a liposome under an epifluorescence microscope by side view (B); Lamellarity distributions of the liposomes prepared by different methods (D). (M. Chiba, et al., 2014)
Why lamellarity analysis is important to liposome?
Liposome lamellarity refers to the number of lipid bilayers of liposomes. Liposomes that prepared by different methods vary quite a lot among their lamellarities. Liposome lamellarity plays a crucial role in determining encapsulation efficiency, mediating diffusion rate of encapsulated agents out of liposomes, controlling drug release, penetration, etc. Moreover, liposome lamellarity has significant effect on the the intracellular fate of the drugs delivered by liposomes after they were taken up or processed in the cell. Therefore, liposome lamellarity is considered as one of the most important parameters needed to be characterized.
Liposome lamellarity determination methods
31P- nuclear magnetic resonance (NMR)
The determination of size and lamellarity of liposome is a direct application of nuclear magnetic resonance (NMR) in liposome quality control. In 31P-NMR, the external shift reagents include Mn2+, Co2+, and Pr3 are widely used. The Mn2+ ion is a paramagnetic ion that is able to interact with the phospholipids, leading to perturbations of the nuclear spin relaxation times of 31P-NMR resonance. Therefore, liposome lamellarity can be analyzed by calculating 31P- NMR signals both before and after adding the shift reagent.
Small angle X-ray scattering (SAXS)
Small angle X-ray scattering (SAXS) is anther widely used techniques for lamellarity determination. Liposomes were put into glass capillaries in this method, and then scattering curves of both the sample and the blank were recorded by a camera with a single-dimensional position sensitive detector. The Indirect Fourier Transformation provides the electron distance distribution p(r) in the measured sample, which helps collect the data. This method provides accurate information of liposome lamellarity.
Other methods for quantitative determination of liposome lamellarity
Label-free differential interference contrast (DIC) microscopy,
Electron microscopy etc.
The thickness and lamellarity level of liposomes can be determined by using imaging analysis for quality control. Our services are cost effective and fast, providing high resolution images and accurate statistical data. Besides lamellarity analysis, Creative Biostructure also provides lots of liposome analysis services listed in related sections to meet our clients’ requirements. Please feel free to contact us for a detailed quote.
M. Chiba, et al. (2014). Quantitative Analysis of the Lamellarity of Giant Liposomes Prepared by the Inverted Emulsion Method. Biophysical Journal, 107: 346-354.
C. Chen, et al. (2013). Analytical techniques for single-liposome characterization. Analytical Methods, 5: 2150–2157.
R. Suzuki, et al. (2014). Mono-cationic detergents play a critical role in the development of liposome-based gene vector via controlling its lamellarity. Nanoscale Research Letters, 16: 2227.