Berts Ida, Fragneto Giovanna, Hilborn Jöns, Rennie Adrian R
Science for Life Laboratory, Department of Chemistry - Ångström Laboratory, Uppsala University, Box 538, 751 21 Uppsala, Sweden.
Eur Phys J E Soft Matter. 2013 Jul;36(7):70. doi: 10.1140/epje/i2013-13070-7. Epub 2013 Jul 16.
The present paper investigates the structure and composition of grafted sodium hyaluronan at a solid-liquid interface using neutron reflection. The solvated polymer at the surface could be described with a density profile that decays exponentially towards the bulk solution. The density profile of the polymer varied depending on the deposition protocol. A single-stage deposition resulted in denser polymer layers, while layers created with a two-stage deposition process were more diffuse and had an overall lower density. Despite the diffuse density profile, two-stage deposition leads to a higher surface excess. Addition of calcium ions causes a strong collapse of the sodium hyaluronan chains, increasing the polymer density near the surface. This effect is more pronounced on the sample prepared by two-stage deposition due to the initial less dense profile. This study provides an understanding at a molecular level of how surface functionalization alters the structure and how surface layers respond to changes in calcium ions in the solvent.
本文利用中子反射技术研究了固液界面处接枝透明质酸钠的结构和组成。表面的溶剂化聚合物可用向本体溶液呈指数衰减的密度分布来描述。聚合物的密度分布因沉积方案而异。单阶段沉积导致聚合物层更致密，而两阶段沉积过程形成的层更弥散且总体密度更低。尽管密度分布弥散，但两阶段沉积导致更高的表面过剩量。钙离子的加入会使透明质酸钠链强烈塌缩，增加表面附近的聚合物密度。由于初始密度较低，这种效应在两阶段沉积制备的样品上更为明显。本研究在分子水平上提供了对表面功能化如何改变结构以及表面层如何响应溶剂中钙离子变化的理解。
