Synthesis of poly(ε-lysine)-grafted dextrans and their pH- and thermosensitive hydrogelation with cyclodextrins
Synthesis of poly(ε-lysine)-grafted dextrans and their pH- and thermosensitive hydrogelation with cyclodextrins
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DOI：
10.1002/cphc.200400598
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发表时间：
2005-06-13
期刊：
影响因子：
2.9
通讯作者：
Yui, N
中科院分区：
文献类型：
--
作者：
Choi, HS;Yamamoto, K;Yui, N
为了获得热可逆超分子结构水凝胶体系的pH敏感性，将聚e -赖氨酸（PL）作为阳离子聚合物接枝到葡聚糖上，并与α -环糊精（α - cds）进行包合。用H-1 NMR对合成的接枝共聚物进行了表征，并通过x射线衍射和固态C-13 NMR分析证实了水凝胶的形成。在pH值为10.0的缓冲溶液中，水合右旋糖酐和疏水聚集的包合物形成相分离结构，引起水化反应。制备的水凝胶表现出热可逆的凝胶-溶胶相变和ph敏感的相变，通过紫外/可见透射率的变化记录了这些相变。当pH值降至4.0时，由于质子化客体聚合物与A - cds之间的解离过程，观察到从凝胶到溶胶的快速相变。通过调节接枝PL的取代度和与a-CDs的结合，改善了水凝胶的刺激响应物理性质。
To give pH sensitivity to a thermoreversible supramolecular-structured hydrogel system, poly(E-lysine) (PL), as a cationic polymer, was grafted to dextran and used for inclusion complexation with alpha-cyclodextrins (alpha-CDs). The synthesized graft copolymer was characterized by H-1 NMR spectroscopy, and the hydrogel formation was confirmed by X-ray diffraction and solid-state C-13 NMR analysis. The hydrogelation was induced from a phase-separated structure of hydrated dextrans and hydrophobically aggregated inclusion complexes in buffer solution at pH 10.0. The prepared hydrogels showed thermoreversible gel-sol transitions as well as pH-sensitive phase transitions, which were recorded by the changes in UV/Vis transmittance. A rapid phase transition from gel to sol was observed upon decreasing the pH value to 4.0, which resulted from the dissociation process between the protonated guest polymer and a-CDs. The stimuli-responsive physical properties of the hydrogels were improved by modulating the degree of substitution of the grafted PL and the combination with a-CDs.