Conceptualisation of articular cartilage as a giant reverse micelle: A hypothetical mechanism for joint biocushioning and lubrication


Autoria(s): Pawlak, Zenon; Oloyede, A.
Data(s)

2008

Resumo

Phospholipid (PL) molecules form the main structure of the membrane that prevents the direct contact of opposing articular cartilage layers. In this paper we conceptualise articular cartilage as a giant reverse micelle (GRM) in which the highly hydrated three-dimensional network of phospholipids is electrically charged and able to resist compressive forces during joint movement, and hence loading. Using this hypothetical base, we describe a hydrophilic-hydrophilic (HL-HL) biopair model of joint lubrication by contacting cartilages, whose mechanism is reliant on lamellar cushioning. To demonstrate the viability of our concept, the electrokinetic properties of the membranous layer on the articular surface were determined by measuring via microelectrophoresis, the adsorption of ions H, OH, Na and Cl on phospholipid membrane of liposomes, leading to the calculation of the effective surface charge density. The surface charge density was found to be -0.08 ± 0.002 cm-2 (mean ± S.D.) for phospholipid membranes, in 0.155 M NaCl solution and physiological pH. This value was approximately five times less than that measured in 0.01 M NaCl. The addition of synovial fluid (SF) to the 0.155 M NaCl solution reduced the surface charge density by 30% which was attributed to the binding of synovial fluid macromolecules to the phospholipid membrane. Our experiments show that particles charge and interact strongly with the polar core of RM. We demonstrate that particles can have strong electrostatic interactions when ions and macromolecules are solubilized by reverse micelle (RM). Since ions are solubilized by reverse micelle, the surface entropy influences the change in the charge density of the phospholipid membrane on cartilage surfaces. Reverse micelles stabilize ions maintaining equilibrium, their surface charges contribute to the stability of particles, while providing additional screening for electrostatic processes. © 2008 Elsevier Ireland Ltd. All rights reserved.

Identificador

http://eprints.qut.edu.au/45895/

Publicador

Elsevier Ireland Ltd

Relação

DOI:10.1016/j.biosystems.2008.05.028

Pawlak, Zenon & Oloyede, A. (2008) Conceptualisation of articular cartilage as a giant reverse micelle: A hypothetical mechanism for joint biocushioning and lubrication. Biosystems, 94(3), pp. 193-201.

Direitos

Copyright 2008 Elsevier Ireland Ltd.

Fonte

Faculty of Built Environment and Engineering; Institute of Health and Biomedical Innovation

Palavras-Chave #060000 BIOLOGICAL SCIENCES #060100 BIOCHEMISTRY AND CELL BIOLOGY #090000 ENGINEERING #090302 Biomechanical Engineering #Cartilage Lubrication, Lamellar Biolubrication, Microelectrophoresis, Surface Charge Density, Liposome, Reverse Micelle
Tipo

Journal Article