Science2014-06-13 5:39 PM

当凝胶不膨胀时,那就太妙了 Nonswellable' Hydrogel Without Mechanical Hysteresis

论文摘要 

由于一项新的研究,水凝胶在生物医学中的应用可能会变得更加广泛。 尽管水凝胶一直被用于包括向体内目标位置的持续性输送药物的应用,但这些果冻样材料(大部分由水组成)通常会在生理条件下膨胀。膨胀会使其变得较薄弱而且它的功效也会降低,而且这也使得在病人体内放入确切容量变得困难,例如在关节中。为了制备更好的水凝胶,如一种能够适应于如渗透压变化等生理条件的水凝胶,Hiroyuki Kamata及其同事求助于制作形状记忆多聚物所用的技巧,形状记忆多聚物被设计成在接触到温度、光线或pH值变化时能改变其形状。他们将一种平常的水凝胶化学与一种会在温度上升时发生收缩反应的成分相结合。因此,当他们的水凝胶从室温情况下的淡水进入到生理环境中时,其膨胀与收缩的趋势会相抵,从而使容量保持恒定。这些凝胶不会像平常的水凝胶那样破裂,即使是在被拉伸至其大小的7倍以上时也是如此。

Abstract 

Hydrogels are three-dimensional polymer networks that contain a large amount of water inside. Certain hydrogels can be injected in solution and transformed into the gel state with the required shape. Despite their potential biomedical applications, the use of hydrogels has been severely limited because all the conventional hydrogels inevitably “swell” under physiological conditions, which drastically degrades their mechanical properties. We report the synthesis of injectable “nonswellable” hydrogels from hydrophilic and thermoresponsive polymers, in which two independently occurring effects (swelling and shrinking) oppose each other. The hydrogels can endure a compressive stress up to 60 megapascals and can be stretched more than sevenfold without hysteresis. Our results demonstrate that the suppression of swelling helps retain the mechanical properties of hydrogels under physiological conditions.

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