The Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel.
The Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 32000, Israel; Department of Chemical Engineering, Technion - Israel Institute of Technology, Haifa 32000, Israel.
Carbohydr Polym. 2015;127:28-37. doi: 10.1016/j.carbpol.2015.03.039. Epub 2015 Mar 27.
We report on intriguing new phenomena related to the creation of chitosan hydrogels crosslinked with genipin. We found that the reaction between chitosan and genipin is very slow, sometimes requiring more than four days until completed. Further, we discovered that altering the pH within the small range of 4.00-5.50 dramatically affects the reaction, leading to hydrogels differing both in appearance and in properties. Increasing the pH by 1.5 units led to an almost fourfold decrease in the gelation time and more than tenfold equilibrium swelling. A correlation between the percentage of unreacted genipin molecules and the hydrogel properties was identified. The strong pH dependency was attributed to the degree of chitosan protonation and to the inability of protonated chitosan to react with genipin. This research shows, for the first time, that minor changes in the pH can lead to substantially different hydrogels.
我们报告了与壳聚糖水凝胶用京尼平交联相关的有趣的新现象。我们发现壳聚糖和京尼平之间的反应非常缓慢，有时需要超过四天才能完成。此外，我们发现改变 pH 值在 4.00-5.50 的小范围内会显著影响反应，导致水凝胶在外观和性质上有所不同。增加 pH 值 1.5 个单位会导致凝胶时间几乎缩短四分之三，平衡溶胀增加十倍以上。确定了未反应的京尼平分子的百分比与水凝胶性质之间的相关性。强 pH 值依赖性归因于壳聚糖质子化的程度和质子化壳聚糖与京尼平反应的能力。这项研究首次表明，pH 值的微小变化可以导致完全不同的水凝胶。
