School of Medical Science and Technology, Indian Institute of Technology, Kharagpur 721 302, India.
Carbohydr Res. 2011 Nov 29;346(16):2582-8. doi: 10.1016/j.carres.2011.08.028. Epub 2011 Sep 1.
Incorporation of phosphate groups into a material may be of particular interest as they act as templates for hydroxyapatite growth through complexation with Ca(2+) and thus improve the osteoconduction property. The phosphate groups can be incorporated into chitosan through ionotropic gelation with tripolyphosphate (TPP). Interestingly, the ion pairs formed through negatively charged phosphate groups with protonated amine functionality of chitosan in ionotropic gelation are expected to provide chitosan with an amphoteric character, which may facilitate protein adhesion following enhanced attachment of anchorage dependant cells than chitosan, which shows poor cell adhesion properties. In this study, chitosan-tripolyphosphate (TPP) fibers with varying phosphate contents were prepared through wet spinning in STPP baths of different pH. Gelation kinetics and gel strength of chitosan with STPP solutions of three different pH were evaluated and compared with that of NaOH solution for evaluation of their influence on nature of gelation. The solution pH of STPP baths was found to have significant control on the extent of ionic cross-linking and physico-chemical properties of the fibers. Moreover, this kinetically driven ionotropic gelation of chitosan by TPP results in low degree of crystallinity of chitosan-TPP fibers and consequently their lower thermal stability than chitosan fibers.
将磷酸基团掺入材料中可能特别有趣，因为它们通过与 Ca(2+) 络合作为羟基磷灰石生长的模板，从而提高了骨传导性。磷酸基团可以通过三聚磷酸钠（TPP）的离子凝胶化掺入壳聚糖中。有趣的是，通过带负电荷的磷酸基团与壳聚糖的质子化氨基功能之间形成的离子对有望赋予壳聚糖两性特征，这可能有助于蛋白质黏附，增强锚定依赖性细胞的附着能力，而壳聚糖的细胞黏附性能较差。在这项研究中，通过在不同 pH 的 STPP 浴中进行湿法纺丝，制备了具有不同磷含量的壳聚糖-三聚磷酸钠（TPP）纤维。评估了壳聚糖与三种不同 pH 的 STPP 溶液的凝胶化动力学和凝胶强度，并与 NaOH 溶液进行了比较，以评估它们对凝胶化性质的影响。发现 STPP 浴的溶液 pH 对纤维的离子交联程度和物理化学性质具有显著的控制作用。此外，TPP 引发的壳聚糖的动力学离子凝胶化导致壳聚糖-TPP 纤维的结晶度降低，因此其热稳定性低于壳聚糖纤维。
