Dedic J, Okur H I, Roke S
Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Department of Chemistry and National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey.
Sci Adv. 2021 Mar 3;7(10). doi: 10.1126/sciadv.abf2558. Print 2021 Mar.
Hyaluronan (HA) is an anionic, highly hydrated bio-polyelectrolyte found in the extracellular environment, like the synovial fluid between joints. We explore the extended hydration shell structure of HA in water using femtosecond elastic second-harmonic scattering (fs-ESHS). HA enhances orientational water-water correlations. Angle-resolved fs-ESHS measurements and nonlinear optical modeling show that HA behaves like a flexible chain surrounded by extended shells of orientationally correlated water. We describe several ways to determine the concentration-dependent size and shape of a polyelectrolyte in water, using the amount of water oriented by the polyelectrolyte charges as a contrast agent. The spatial extent of the hydration shell is determined via temperature-dependent measurements and can reach up to 475 nm, corresponding to a length of 1600 water molecules. A strong isotope effect, stemming from nuclear quantum effects, is observed when light water (HO) is replaced by heavy water (DO), amounting to a factor of 4.3 in the scattered SH intensity.
透明质酸（HA）是一种阴离子型、高度水合的生物聚电解质，存在于细胞外环境中，如关节之间的滑液。我们使用飞秒弹性二次谐波散射（fs-ESHS）来探索HA在水中的扩展水合壳结构。HA增强了取向水-水相关性。角度分辨fs-ESHS测量和非线性光学建模表明，HA的行为类似于被取向相关水的扩展壳包围的柔性链。我们描述了几种使用被聚电解质电荷取向的水量作为对比剂来确定水中聚电解质浓度依赖性大小和形状的方法。水合壳的空间范围通过温度依赖性测量确定，可达475纳米，相当于1600个水分子的长度。当轻水（H₂O）被重水（D₂O）取代时，观察到源于核量子效应的强烈同位素效应，散射的二次谐波强度增加了4.3倍。
