Kang H W, Tabata Y, Ikada Y
Institute for Frontier Medical Sciences, Kyoto University, Japan.
Biomaterials. 1999 Jul;20(14):1339-44. doi: 10.1016/s0142-9612(99)00036-8.
A novel method which employs water present in swollen hydrogels as a porogen for shape template was suggested for preparing porous materials. Biodegradable hydrogels were prepared through crosslinking of gelatin with glutaraldehyde in aqueous solution, followed by rinsing and washing. After freezing the swollen hydrogels, the ice formed within the hydrogel network was sublimated by freeze-drying. This simple method produced porous hydrogels. Irrespective of any rinsing and washing processes, water was homogeneously distributed into the hydrogel network, allowing the hydrogel network to uniformly enlarge and the ice to act as a porogen during the freezing process. Different porous structures were obtained by varying the freezing temperature. Hydrogels frozen in liquid nitrogen, had a two-dimensionally ordered structure, while the hydrogels prepared at freezing temperatures near -20 degrees C, showed a three-dimensional structure with interconnected pores. As the freezing temperature was lowered, the hydrogel structure gradually became more two-dimensionally ordered. These results suggest that the porosity of dried hydrogels can be controlled by the size of ice crystals formed during freezing. It was concluded that the present freeze-drying procedure is a bio-clean method for formulating biodegradable sponges of different pore structures without use of any additives and organic solvents.
提出了一种新方法，该方法利用溶胀水凝胶中的水作为形状模板的致孔剂来制备多孔材料。通过在水溶液中将明胶与戊二醛交联，然后冲洗和洗涤来制备可生物降解的水凝胶。将溶胀的水凝胶冷冻后，通过冷冻干燥升华水凝胶网络内形成的冰。这种简单的方法产生了多孔水凝胶。无论任何冲洗和洗涤过程，水都均匀地分布在水凝胶网络中，使得水凝胶网络均匀膨胀，并且冰在冷冻过程中充当致孔剂。通过改变冷冻温度获得了不同的多孔结构。在液氮中冷冻的水凝胶具有二维有序结构，而在接近-20℃的冷冻温度下制备的水凝胶显示出具有相互连接孔隙的三维结构。随着冷冻温度降低，水凝胶结构逐渐变得更加二维有序。这些结果表明，干燥水凝胶的孔隙率可以通过冷冻过程中形成的冰晶尺寸来控制。得出的结论是，目前的冷冻干燥程序是一种生物清洁方法，用于在不使用任何添加剂和有机溶剂的情况下制备具有不同孔结构的可生物降解海绵。
