Study of Chitin and Chitosan for Bio-medical Materials Application

我们发现甲壳素溶解在氯化钙二水饱和甲醇中形成透明的溶液。在简单的研究中，甲壳素的溶解行为取决于溶液中的钙、甲醇和水的含量。由于甲壳素在高含水率介质中的溶解度急剧下降，在甲壳素溶液中加入水形成了甲壳质水凝胶。得到的材料是一种高度膨胀的水凝胶，其水分含量超过95%。透析是必要的，以去除水凝胶中多余的钙。同样，在甲壳素溶液中加入甲醇也可以得到凝胶状的材料。然而，从甲壳素溶液中沉淀出来需要两倍量的甲醇。此外，有必要进行长期透析，以去除凝胶材料中的钙。这些结果表明甲壳素水凝胶的溶解条件是不同的。对甲壳素水凝胶的性质进行了多种测试。比较了甲壳素水凝胶与粉状甲壳素的酶消化速度。用几丁质酶和溶菌酶消化几丁质水凝胶比粉末快10倍左右。结果表明，甲壳素水凝胶具有良好的生物相容性和生物消化特性，适合于生物医学应用。甲壳素水凝胶中的水分去除后，甲壳素再次再生。在此基础上，利用常规过滤装置进行除水，得到甲壳素片材。一旦甲壳素水凝胶中的水被除去，加入的水就不会再得到水凝胶。这种现象可能是通过甲壳素分子间氢键网络的再生来实现的。这张纸非常有趣，因为这张纸是由100%的甲壳素制成的，没有任何胶水。染料吸附实验表明，阴离子染料具有较高的选择性，提示有可能作为药物输送系统的载体。

We have found that chitin dissolves in calcium chloride dihydrate saturated methanol to form a clear solution. In the briefly study, solubility behavior of chitin depend on the calcium, methanol and water content of the solution. Since the solubility of chitin decreased drastically in the medium of high water content, the chitin hydro gel appeared by the addition of water in the chitin solution. Obtained material was a highly swelled hydro gel containing more than 95 % of water. Dialysis was necessary to remove excess calcium from the hydro gel. In the same manner, addition of methanol in the chitin solution also gave gel like material. However, two fold amount of methanol was required to precipitate out from the chitin solution. In addition, long term dialysis was necessary to remove calcium from the gel material. These results suggest that the solubility condition is different from each other.Properties of the chitin hydro gel were examined by several manners. Enzyme digestion rate of chitin hydro gel was compared with that of powder. Chitin hydro gel digested about ten times faster than powder using chitinase and lysozime. The results strongly suggests that chitin hydro gel has excellent biocompatible and biodigestive feature and is appropriate for bio medical usage. Removal of water from the chitin hydro gel regenerated chitin again. Based on the result, the removal of water by the use of conventional filtration apparatus gave chitin sheet. Once the water was removed from the chitin hydro gel, addition of water did not gave hydro gel again. The phenomenon may be carried out by the regeneration of hydrogen bond network between chitin molecules. The sheet is very interesting because this is a sheet made up of 100 % of chitin without of any glue. Dye adsorption examination afforded high preference for anionic dye, which suggest the possibility for the carrier of drug delivery system.