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Updated: Dec 24, 2025
10:15
Atomic Force Microscopy Imaging and Force Spectroscopy of Supported Lipid Bilayers
Published on: July 22, 2015
15.3K
Normal and shear forces between boundary sphingomyelin layers under aqueous conditions
Yifeng Cao1, Nir Kampf1, Weifeng Lin1
1Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 76100, Israel. Jacob.klein@weizmann.ac.il.
Soft Matter
|April 7, 2020
Summary
Sphingomyelin acts as an excellent boundary lubricant in joints, reducing friction between cartilage surfaces. This phospholipid contributes significantly to the natural lubrication of synovial joints, similar to phosphatidylcholine.
Area of Science:
- Biophysics
- Tribology
- Biochemistry
Background:
- Lipids, particularly sphingomyelin, are crucial for the boundary lubrication of articular cartilage in synovial joints.
- The lubrication behavior of sphingomyelin has been under-investigated despite its abundance in joints.
Purpose of the Study:
- To investigate the boundary lubrication properties of sphingomyelin under aqueous conditions.
- To quantify the friction and normal forces of sphingomyelin layers using a surface force balance.
Main Methods:
- Egg sphingomyelin vesicles adsorbed onto mica surfaces via calcium bridging or salt screening.
- Measurement of normal and shear forces using a surface force balance.
- Calculation of friction coefficients at varying contact stresses and ionic conditions.
Main Results:
- Sphingomyelin layers exhibited long-range weak repulsion and short-range strong repulsion.
- Achieved very low friction coefficients, ranging from (7.2 ± 1.7) × 10-4 to (0.8-3.5) × 10-3.
- Friction coefficients in water were comparable to those of known biolubricants like phosphatidylcholine.
Conclusions:
- Sphingomyelin demonstrates excellent boundary lubrication capabilities, attributed to hydration lubrication.
- Sphingomyelin plays a vital role in the lubrication of synovial joints, alongside phosphatidylcholine.
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