Anisotropic Structure of Calcium-Induced Alginate Gels by Optical and Small-Angle X-ray Scattering Measurements
Anisotropic Structure of Calcium-Induced Alginate Gels by Optical and Small-Angle X-ray Scattering Measurements
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DOI：
10.1021/bm200223p
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发表时间：
2011-06-01
影响因子：
6.2
通讯作者：
Wakabayashi, Katsuzo
中科院分区：
文献类型：
--
作者：
Maki, Yasuyuki;Ito, Kei;Wakabayashi, Katsuzo
首次报道在阳离子流作用下制备的海藻酸盐凝胶出现双折射现象是在50多年前，但对海藻酸盐凝胶的各向异性结构尚未进行详细研究。在本研究中，制备各向异性的钙-海藻酸盐凝胶内透析管中的高钙浓度的外部浴，并进行光学和小角X射线散射（SAXS）测量，以表征凝胶的结构。用正交偏振器和圆偏振器观察凝胶显示分子取向垂直于Ca 2+流动的方向。SAXS强度分布的分析表明，形成的棒状原纤维组成的几十个藻酸盐分子和凝胶的各向异性是由大原纤维的圆周方向。从观察到的不对称SAXS图案，发现各向异性结构的旋转对称轴平行于Ca 2+流动的方向。从SAXS强度数据计算的排列因子（A（f））证实了原纤维的取向垂直于Ca 2+流动的方向。
It was more than 50 years ago that an appearance of birefringence in alginate gels prepared under cation flow was reported for the first time, however, the anisotropic structure of the alginate gel has not-been studied in detail.. In the present study, anisotropic Ca-alginate gels were prepared within dialysis tubing in a high Ca2+-concentration external bath, and optical and small-angle X-ray scattering (SAXS) measurements were performed to characterize the structure of the gel. The observation of the gel with crossed polarizers and with circular polarizers revealed the molecular orientation perpendicular to the direction of Ca2+ flow. Analysis of the SAXS intensity profiles indicated the formation of rod-like fibrils consisting of a few tens of alginate molecules and that the anisotropy of the gel was caused by the circumferential orientation of the large fibrils. From the Observed asymmetric SAXS pattern, it was found that the axis of rotational symmetry of the anisotropic structure was parallel to the direction Ca2+ flow. The alignment factor (A(f)) calculated from the SAXS intensity data confirmed that the orientation of the fibrils was perpendicular to the direction of Ca2+ flow.