Department of Physical-Chemistry, Institute of Chemistry, University of Campinas, UNICAMP, PO Box 6154, 13084-862, Campinas, SP, Brazil.
Carbohydr Res. 2010 Nov 2;345(16):2368-73. doi: 10.1016/j.carres.2010.08.015. Epub 2010 Aug 27.
Gels of κ-carrageenan were prepared in H₂O and D₂O. Rheological measurements revealed that in heavy water the elastic modulus is substantially higher. From the rheological view point, this result indicates the formation of a higher number of physical-crosslinking points in the structure of the gel. These crosslinking points are mainly associated with the aggregation of the double-helix of the κ-carrageenan, which is enhanced in D₂O. The thermal stability of the gels in both solvents (relative to the sol-gel transition) was also investigated by using polarimetric measurements (to measure the relative fraction of helix-coil) and micro-differential scanning calorimetry (micro-DSC). The results obtained using these techniques are very consistent and allow us to propose a model to explain the differences for the gels formed in light and heavy water based on the degree of double-helix aggregation.
κ-卡拉胶凝胶分别在 H₂O 和 D₂O 中制备。流变学测量表明，在重水中弹性模量显著提高。从流变学的角度来看，这一结果表明在凝胶结构中形成了更多的物理交联点。这些交联点主要与 κ-卡拉胶双螺旋的聚集有关，在 D₂O 中这种聚集得到增强。还通过偏光测量（测量螺旋-线圈的相对分数）和微差示扫描量热法（micro-DSC）研究了两种溶剂中凝胶的热稳定性（相对于溶胶-凝胶转变）。这些技术得到的结果非常一致，使我们能够提出一个模型，基于双螺旋聚集程度来解释在轻水和重水中形成的凝胶之间的差异。
