Role of the biomolecular interactions in the structure and tribological properties of synovial fluid

The analysis of healthy rat synovial fluid (SF) by electron microscopy proved the existence of lipid multilamellar vesicular discontinuities of several hundred nm in diameter. To understand the discontinuities' role in biolubrication, their intermolecular and tribological properties were studied using AFM and biotribological techniques. Hyaluronic acid and lubricin exhibited high affinity and high friction coefficients for lipid bilayers while biomimetic SF vesicles including glycoproteic components conferred low friction coefficients. These results suggest that SF's volume is composed by a network of vesicles containing glycoproteic gel separated by lipid multilayers, lubricin's role being devoted to anchor lipid layers on the cartilage. (c) 2012 Elsevier Ltd. All rights reserved.