Materials Science and Engineering Department, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.
Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830.
Biointerphases. 2023 Apr 11;18(2):021005. doi: 10.1116/6.0002502.
Interactions between molecules in the synovial fluid and the cartilage surface may play a vital role in the formation of adsorbed films that contribute to the low friction of cartilage boundary lubrication. Osteoarthritis (OA) is the most common degenerative joint disease. Previous studies have shown that in OA-diseased joints, hyaluronan (HA) not only breaks down resulting in a much lower molecular weight (MW), but also its concentration is reduced ten times. Here, we have investigated the structural changes of lipid-HA complexes as a function of HA concentration and MW to simulate the physiologically relevant conditions that exist in healthy and diseased joints. Small angle neutron scattering and dynamic light scattering were used to determine the structure of HA-lipid vesicles in bulk solution, while a combination of atomic force microscopy and quartz crystal microbalance was applied to study their assembly on a gold surface. We infer a significant influence of both MW and HA concentrations on the structure of HA-lipid complexes in bulk and assembled on a gold surface. Our results suggest that low MW HA cannot form an amorphous layer on the gold surface, which is expected to negatively impact the mechanical integrity and longevity of the boundary layer and could contribute to the increased wear of the cartilage that has been reported in joints diseased with OA.
滑液中的分子与软骨表面之间的相互作用可能在形成吸附膜中发挥重要作用，这些吸附膜有助于软骨边界润滑的低摩擦。骨关节炎（OA）是最常见的退行性关节疾病。先前的研究表明，在 OA 病变关节中，透明质酸（HA）不仅分解导致分子量（MW）大大降低，而且浓度降低十倍。在这里，我们研究了脂质-HA 复合物的结构变化作为 HA 浓度和 MW 的函数，以模拟健康和患病关节中存在的生理相关条件。小角中子散射和动态光散射用于确定 bulk solution 中 HA-脂质囊泡的结构，而原子力显微镜和石英晶体微天平的组合则用于研究它们在金表面上的组装。我们推断 MW 和 HA 浓度对 bulk 和组装在金表面上的 HA-脂质复合物的结构有显著影响。我们的结果表明，低 MW 的 HA 不能在金表面上形成非晶层，这预计会对边界层的机械完整性和耐久性产生负面影响，并可能导致 OA 患病关节中报道的软骨磨损增加。
