pH-triggered shape response of cubical ultrathin hydrogel capsules
pH-triggered shape response of cubical ultrathin hydrogel capsules
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DOI：
10.1039/c2sm25641j
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发表时间：
2012-01-01
期刊：
影响因子：
3.4
通讯作者：
Kharlampieva, Eugenia
中科院分区：
文献类型：
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作者：
Kozlovskaya, Veronika;Wang, Yun;Kharlampieva, Eugenia
我们报告了两种基于聚甲基丙烯酸 (PMAA) 的立方体水凝胶微容器（胶囊），它们对 pH 变化的形状响应明显不同。通过氢键逐层（LbL）薄膜的化学交联，将微容器制备为立方体无机模板的复制品。两种类型的中空水凝胶，即单组分 (PMAA) 和 PMAA-聚(N-乙烯基吡咯烷酮) (PMAA-PVPON)，在形状对 pH 变化的响应方面表现出巨大差异。当从 pH 3 过渡到 pH 8 时，立方体 (PMAA) 20 胶囊变成相同尺寸的凸出球形结构。相比之下，立方体 (PMAA-PVPON)(5) 胶囊在 pH 3 时保持其立方体形状，而在 pH 8 时尺寸增加。pH 触发的立方体胶囊尺寸变化是完全可逆的。 pH 触发的形状响应的差异通过水凝胶刚性的差异合理化，水凝胶刚性的差异表示为相邻交联之间的聚合物轮廓长度与持久性聚合物长度的比率。 (PMAA) 和 (PMAA-PVPON) 系统的比率分别为 22.7 和 2，表明双组件系统更加刚性，因此在所有方向上均匀膨胀。我们相信，这些结果为开发具有可预测形状和尺寸变化特性的聚合物材料提供了新的前景，用于微流体装置中受控药物输送、细胞摄取和 pH 调节运输行为。
We report on two types of poly(methacrylic acid) (PMAA)-based hydrogel microcontainers (capsules) of cubical shape with distinctly different shape responses upon pH variations. The microcontainers were prepared as replicas of cubical inorganic templates through chemical cross-linking of hydrogen-bonded layer-by-layer (LbL) films. The two types of hollow hydrogels, a single-component (PMAA) and PMAA-poly(N-vinylpyrrolidone) (PMAA-PVPON), showed drastic differences in their shape response to pH variations. Cubical (PMAA) 20 capsules turned into bulged sphere-like structures of the same size when transitioned from pH 3 to pH 8. In contrast, cubical (PMAA-PVPON)(5) capsules retained their cubical shape at pH 3 while increasing in size at pH 8. The pH-triggered size change of cubical capsules was completely reversible. The difference in pH-triggered shape responses was rationalized through the difference in hydrogel rigidity expressed as the ratio of the polymer contour length between the neighboring cross-links to the persistence polymer length. The ratios of 22.7 and 2 for (PMAA) and (PMAA-PVPON) systems, respectively, suggested that the dual-component system is more rigid and therefore expands uniformly in all directions. We believe that the results provide new prospects for developing polymeric materials with predictable shape and size-changing properties for controlled drug delivery, cellular uptake, and pH-regulating transport behavior in microfluidic devices.