可调节的基于鸟苷的超分子水凝胶的结构和胶凝机理,Langmuir

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可调节的基于鸟苷的超分子水凝胶的结构和胶凝机理
Langmuir ( IF 3.7 ) Pub Date : 2010-04-12 00:00:00 , DOI: 10.1021/la100211y
Zheng Li ₁ , Lauren E. Buerkle ₁ , Maxwell R. Orseno ₂ , Kiril A. Streletzky ₂ , Soenke Seifert ₃ , Alexander M. Jamieson ₁ , Stuart J. Rowan ₁

Affiliation

利用静态光散射的组合研究了50/50 w / w鸟苷（G）和2'，3'，5'-三-O-乙酰鸟苷（TAcG）的混合物在0.354 M KCl水溶液中的凝胶化机理。SLS），偏振和去偏振动态光散射（VV和VH DLS），小角中子和X射线散射（SANS和SAXS）以及粘度测试。SLS和粘度测定法分别在0.2 wt％和0.3 wt％时表观分子量和流体力学体积显着增加，表明G / TAcG自缔合的临界浓度进入柱状组件的四重态含量低于0.2 wt％。超过此浓度时，SANS和SAXS会生成有关各个柱状烟囱结构的补充信息。VV和VH DLS结果表明双峰相关函数，其性质分别暗示了双峰分布的粒子的平移和旋转扩散。快速模式似乎源自G / TAcG柱状四方组装体的原纤维团聚体，而慢速模式则来自微凝胶域。SLS数据的Guinier图分析探查了微凝胶域的内部结构。总体而言，结果表明溶胶和微凝胶相共存于宏观凝胶点以下，并且溶胶相包含单独的G / TAcG柱状堆叠体这些柱状组件的横向聚集形成了四重态和原纤维聚集体。随着浓度的增加，DLS数据表明微凝胶域的体积分数逐渐增加，最终导致宏观凝胶化。在低温下对瞬态网络对凝胶流变性的贡献的先前观察归因于凝胶网络内单个柱状叠层的存在。

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Structure and Gelation Mechanism of Tunable Guanosine-Based Supramolecular Hydrogels

The mechanism of gelation of 50/50 w/w mixtures of guanosine (G) and 2′,3′,5′-tri-O-acetylguanosine (TAcG) in aqueous 0.354 M KCl was investigated using a combination of static light scattering (SLS), polarized and depolarized dynamic light scattering (VV and VH DLS), small-angle neutron and X-ray scattering (SANS and SAXS), and viscometric experiments. SLS and viscometry show a dramatic increase in apparent molecular weight and hydrodynamic volume at 0.2 wt % and 0.3 wt %, respectively, indicating the critical concentration for self-association of G/TAcG quartets into columnar assemblies lies below 0.2 wt %. Above this concentration, SANS and SAXS generate complementary information on the structure of the individual columnar stacks. VV and VH DLS results indicate bimodal correlation functions, whose properties suggest, respectively, translational and rotational diffusion of a bimodal distribution of particles. The fast mode appears to originate from fibrillar agglomerates of G/TAcG columnar quartet assemblies, while the slow mode comes from microgel domains. Guinier plot analysis of the SLS data probes the internal structure of the microgel domains. Collectively, the results suggest that sol and microgel phases coexist below the macroscopic gel point, and that the sol phase contains individual columnar stacks of G/TAcG quartets and fibrillar aggregates formed via lateral aggregation of these columnar assemblies. With increasing concentration, the DLS data indicate a progressive increase in the volume fraction of microgel domains, which ultimately leads to macroscopic gelation. Prior observation of a transient network contribution to the gel rheology at low temperature is attributed to the presence of individual columnar stacks within the gel network.

更新日期：2010-04-12

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