The Friction on Cartilage Surfaces under Variable Wettability
Journal Title: Biomedical Journal of Scientific & Technical Research (BJSTR) - Year 2018, Vol 6, Issue 5
Abstract
The wettability of the articular surface of cartilage depends on the condition of its surface-active phospholipid overlay, which is structured as a multi-bilayer. We examined the characteristics of this membrane surface entity in both its normal and degenerated conditions using a combination of atomic force microscopy, contact angle measurement, and friction test. The observations have led to the conclusions that the friction coefficient is significantly dependent on the hydrophobicity (wettability) of the surface of the tissue, thereby confirming the hypothesis tested in this paper. Phospholipids are molecules present in various tissues and body fluids which are also named surfactants, substances which lower surface energy [1-3].The main phospholipid classes adsorbed onto the surface of cartilage surface-active phospholipids (SAL) were identified and quantified: phosphatidylcholine (41%), phosphatidyl ethanol amine (27%) and sphingomyelin (32%) were identified as the major components of the lipid bilayer coating a natural intact cartilage surface [4,5]. The human body naturally produces phospholipids. Phospholipids support most functions of organs, such as cardiovascular health, nerve health, liver function, digestion and, most importantly, certain phospholipids might act as boundary lubricants [1]. (Figure 1) (a) An electron microscopy image of the articular cartilage surface of a human knee demonstrating the oligo lamellar lining consisting of phospholipid bilayers [3]. The bar represents 50 nm and (b) Book cover “Articular cartilage: Lamellar-repulsive lubrication of natural joints” [1]. This smart surface characteristic creates a hydrophobic-hydrophilic balance resulting in a functional hydrophilic surface in the intact joint. One of the quantitative indicators of surface tribo chemical properties is wettability. This is measured as the contact angle between a drop of water and the reference surface, see (Figure 2a).
Authors and Affiliations
Aleksandra Mrela, Zenon Pawlak
Keywords
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- EP ID EP585809
- DOI 10.26717/BJSTR.2018.06.001404
- Views 151
- Downloads 0
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