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Small-Angle Neutron Scattering Study of Temperature-Induced Structural Changes in Liposomes
Sofiya Matviykiv1, Hans Deyhle1, Joachim Kohlbrecher2
1Biomaterials Science Center, Department of Biomedical Engineering , University of Basel , Allschwil 4123 , Switzerland.
Langmuir : the ACS Journal of Surfaces and Colloids
|July 26, 2019
Summary
Artificial liposomes show temperature-dependent structural changes. Pad-PC-Pad liposomes flatten and thicken, making them unsuitable for drug delivery, while Rad-PC-Rad liposomes remain stable for in-body applications.
Area of Science:
- Materials Science
- Biotechnology
- Physical Chemistry
Background:
- Artificial phospholipids form mechanically responsive liposomes capable of releasing therapeutics in response to physical stimuli like blood flow.
- Understanding liposome structural changes within the physiological temperature range (22-42 °C) is crucial for targeted drug delivery applications.
Purpose of the Study:
- To investigate the temperature-induced structural alterations of specific artificial liposomes (Pad-PC-Pad, Rad-PC-Rad, etc.) between 22 and 42 °C.
- To determine the suitability of these liposomes for drug delivery in the human vasculature, particularly in atherosclerotic conditions.
Main Methods:
- Small-angle neutron scattering (SANS) was utilized to analyze liposome structure as a function of temperature.
- Cryogenic transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS) were employed to corroborate SANS findings and assess liposome morphology.
Main Results:
- Liposomes like Rad-PC-Rad, Pad-Pad-PC, Sur-PC-Sur, and Sad-PC-Sad exhibited stable structures as their phase transition temperatures exceeded 42 °C.
- Pad-PC-Pad and Pes-PC-Pes liposomes, with phase transitions below 42 °C, showed significant structural changes: flattening (decreased eccentricity) and increased bilayer thickness (20%) due to lost interdigitation.
- Pad-PC-Pad liposomes demonstrated thermal instability within the relevant physiological range.
Conclusions:
- Pad-PC-Pad liposomes are not suitable for local drug delivery in the human atherosclerotic vasculature due to temperature-induced structural destabilization.
- Rad-PC-Rad liposomes exhibit thermal stability and are promising candidates for in-body therapeutic applications.
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