Chen Xinyue, Richter Ralf P
CIC biomaGUNE, San Sebastian, Spain.
School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK.
Interface Focus. 2019 Apr 6;9(2):20180061. doi: 10.1098/rsfs.2018.0061. Epub 2019 Feb 15.
Hyaluronan (HA) is a linear, regular polysaccharide that plays as a chief structural and functional component in peri- and extracellular matrices, thus contributing significantly to many basic cellular processes. To understand more comprehensively the response of the supramolecular organization of HA polymers to changes in their aqueous environment, we study the effects of Ca concentration and pH on the morphology and rigidity of films of end-grafted HA polymers on planar supports (HA brushes), as a well-defined model system of HA-rich matrices, by reflection interference contrast microscopy and quartz crystal microbalance. The thickness and softness of HA brushes decrease significantly with Ca concentration but do not change with pH, within the physiological ranges of these parameters. The effect of Ca on HA brush thickness is virtually identical to the effect of Na at 10-fold higher concentrations. Moreover, the thickness and softness of HA brushes decrease appreciably upon HA protonation at pH less than 6. Effects of pH and calcium ions are fully reversible over large parameter ranges. These findings are relevant for understanding the supramolecular organization and dynamics of HA-rich matrices in biological systems and will also benefit the rational design of synthetic HA-rich materials with tailored properties.
透明质酸（HA）是一种线性规则多糖，在细胞周围和细胞外基质中作为主要的结构和功能成分，对许多基本细胞过程有重要贡献。为了更全面地了解HA聚合物超分子组织对其水环境变化的响应，我们通过反射干涉对比显微镜和石英晶体微天平，研究了钙浓度和pH值对平面支撑物上末端接枝HA聚合物薄膜（HA刷）的形态和刚性的影响，HA刷是富含HA的基质的一个明确模型系统。在这些参数的生理范围内，HA刷的厚度和柔软度随钙浓度显著降低，但不随pH值变化。钙对HA刷厚度的影响与浓度高10倍的钠的影响几乎相同。此外，在pH值小于6时，HA质子化会使HA刷的厚度和柔软度明显降低。在较大参数范围内，pH值和钙离子的影响是完全可逆的。这些发现有助于理解生物系统中富含HA的基质的超分子组织和动力学，也将有利于合理设计具有定制特性的合成富含HA的材料。
