Effects of hyaluronan molecular weight on the lubrication of cartilage-emulating boundary-layers.

Effects of hyaluronan molecular weight on the lubrication of cartilage-emulating boundary-layers. Biomacromolecules. 2020 Sep 15;: Authors: Liu Z, Lin W, Fan Y, Kampf N, Wang Y, Klein J Abstract Osteoarthritic joints contain lower molecular weight (MW) hyaluronan (hyaluronic acid, HA) than healthy joints. To understand the relevance of this HA-size effect for joint lubrication, the friction and surface structure of cartilage-emulating surfaces with HA of different MW were studied using a surface force balance (SFB), and atomic force microscopy (AFM) . Gelatin (gel)-covered mica surfaces were coated with either high MW HA (HHA), medium MW HA (MHA) or low MW HA (LHA), and lipids of Hydrogenated Soy L-α-phosphatidylcholine (HSPC) in the form of small unilamellar vesicles, using a layer-by-layer assembly method. SFB results indicate that the gel-HHA-HSPC boundary layer provides very efficient lubrication, attributed to hydration lubrication at the phosphocholine head-groups exposed by the HA-attached lipids, with friction coefficients (COF) as low as l0-3-10-4 at contact stresses at least up to P = 120 atm. However, for the gel-MHA-HSPC and gel-LHA-HSPC surfaces, the friction, initially low, increases sharply at much lower pressures (up to 30-60 atm at most). This higher friction with the shorter chains may be due to their weaker total adhesion energy to the gelatin, where the attraction between the negatively-charged HA and the weakly-...
Source: Biomacromolecules - Category: Biochemistry Authors: Tags: Biomacromolecules Source Type: research