Date recorded: January 23 2018

Duration: 47 minutes 44 seconds

Liposomes have been used in drug discovery and drug delivery for some time, and the biophysical characterization of these systems and their payloads is critical to understanding and optimizing their fabrication and function. This study looks at optimal conditions for extruding liposomes as well as their stability under different conditions. 

Our aim is to further educate the public about the intricacies of liposome formation and characterization as measured by Nanoparticle Tracking Analysis (NTA) from the NanoSight product range, Dynamic and Electrophoretic Light Scattering (DLS/ELS) from the Zetasizer product range, and Small-angle and Wide-angle X-ray scattering (SAXS/WAXS) from the X-ray analytical product range within Malvern Panalytical. 

A broad range of characterization information and combination of both NanoSight and Zetasizer systems helped further optimize fabrication and understand the function of liposomes as well as labeling efficiency of fluorescent lipids.  NTA through NanoSight provided number-based high resolution sizing, accurate distribution profiles, concentration (particles/mL), and fluorescence measurements.  DLS provided excellent reproducibility, mean size and PDI measurements over a broad range and non-invasive trend analysis.  ELS provided zeta potential as a functionality and stability metric of particles.  SAXS allowed to investigate the bilayer stacking in MLVs and from WAXS data the order of the alkyl chains (gel phase vs. liquid phase) could be studied as a function of sample temperature.

Table of contents
1. Welcome
00:11
2. Ragy Ragheb
00:33
3. Characterizing Liposome Formation, Structure, and Stability with Complementary Techniques
00:14
4. What are liposomes ?
00:51
5. Liposomes
01:14
6. Liposome preparation
00:34
7. Liposome extrusion
01:08
8. Malvern Panalytical’s tools for this study
00:28
9. Liposome characterization solutionsoffered by Malvern Panalytical
01:20
10. Zetasizer: Dynamic and Electrophoretic Light Scattering
00:19
11. Dynamic Light Scattering and Brownian Motion
00:23
12. Dynamic Light Scattering (DLS)
00:29
13. Intensity Fluctuations, Correlation, and Size Distributions
00:37
14. Zeta Potential
00:47
15. Electrophoretic Light Scattering
00:38
16. Laser Doppler Electrophoresis
00:21
17. NanoSight – Nanoparticle Tracking Analysis
00:11
18. Seeing is Believing!
00:00
19. Patented Optical Arrangement
00:56
20. Concentration: Quantify particles in known volume
00:00
21. Parameters measured by NTA
00:55
22. Zetasizer and NanoSight results
00:11
23. DOPC, 2mg/mL, checking size by extrusion pass # with various pore-sizes
00:36
24. Effect of varying lipid concentration on extrusion sizing by pass # through 100nm pore size
00:22
25. Effect of Freeze / Thaw cycles (5x) on particle size and concentration as extruded through 100 nm pores
00:25
26. Effect of Freeze / Thaw cycles (5x) on particle size and concentration as extruded through 100 nm pores
00:41
27. Effect of both Freeze / Thaw cycles (5x) and Step-Down extrusion on particle size and concentration (11x passes/pore size)
01:10
28. Effect of both Freeze / Thaw cycles (5x) and Step-Down extrusion on particle size and concentration (11x passes/pore size)
00:32
29. Effect of % Cholesterol on size, concentration, and zeta potential (1mM NaCl + 0.1mM MOPS) with diffusion barrier method
01:34
30. Effect of % Cholesterol on size, concentration, and zeta potential (1mM NaCl + 0.1mM MOPS) with diffusion barrier method
00:24
31. 2 mg/mL DOPC with varying mol% Rh-DPPE Fluorescence-mode concentration efficiency of Rhodamine labeled liposomes as a function of increasing dye loadings.
01:28
32. SAXS / WAXS on liposomes
01:20
33. What is SAXS ?
01:12
34. Schematics of a SAXS experiment
00:05
35. Schematics of a SAXS / WAXS experiment
01:15
36. EmpyreanVersatile platform for X-ray scattering & diffraction experiments
00:49
37. Experimental setup for SAXS / WAXS
01:01
38. SAXS and WAXS measurements
00:27
39. Temperature-controlled capillary holder
00:05
40. Investigated samples
01:34
41. Untitled
00:08
42. DPPC @ 20°CBefore extrusion - multilamellar vesicles
00:05
43. DPPC at different temperaturesBefore extrusion
00:58
44. DPPC at differenttemperatures Before extrusion
02:27
45. DPPC at different temperaturesBefore extrusion
01:43
46. DPPC vs. DOPC @ T = 20°CBefore extrusion
01:00
47. Untitled
00:15
48. DPPC @ T = 20°Cbefore and after extrusion
00:54
49. DPPC @ T = 20°Cafter extrusion
00:52
50. Electron density profile across a lipid bilayer
01:30
51. Model calculationUni-lamellar vesicle
01:30
52. Model calculationVariation of lamellarity N
00:05
53. DPPC @ T = 20°Cafter extrusion
00:42
54. Summary and conclusions
02:02
55. Thank you for attention
06:13