Ferreira L, Figueiredo M M, Gil M H, Ramos M A
INEB-Instituto de Engenharia Biomédica, Laboratório de Biomateriais, Rua do Campo Alegre 823, 4150-180 Porto, Portugal.
J Biomed Mater Res B Appl Biomater. 2006 Apr;77(1):55-64. doi: 10.1002/jbm.b.30394.
This work reports the results of structural analysis in novel dextran-acrylate (dexT70-VA) hydrogels generated chemoenzymatically. Porous structure as well as hydrogel surface and interior morphologies were evaluated by mercury intrusion porosimetry (MIP), nitrogen adsorption (NA), and scanning electron microscopy (SEM) analyses, as a function of the degree of substitution (DS), and initial water content used in the preparation of the hydrogel. MIP analysis showed that the overall networks were clearly macroporous with pore sizes ranging from 0.065 to 10 microm. As expected, the average pore size decreased as DS increased and as initial water content decreased. Moreover, the porosity values ranged from 75 up 90%, which shows that these hydrogels present an interconnected pore structure. Nitrogen adsorption analyses showed that the specific surface area of dexT70-VA hydrogels increased either by increasing the DS or by decreasing the initial water content of the hydrogel. SEM results revealed that the surface of hydrogels with lower DS presented either a porous structure or a polymeric "skin" covering the pores, whereas hydrogels with higher DS were totally porous. Furthermore, the interior morphology varied according to the DS and the initial water content of the hydrogels. Finally, the average pore size was also determined from the swelling of hydrogel using a theoretical model developed by Flory-Rehner. The comparison of the SEM and MIP results with the ones obtained by the equilibrium swelling theory of Flory-Rehner shows that this approach highly underestimates the average pore size.
本研究报告了通过化学酶法制备的新型葡聚糖 - 丙烯酸酯（dexT70 - VA）水凝胶的结构分析结果。通过压汞法（MIP）、氮吸附（NA）和扫描电子显微镜（SEM）分析，评估了多孔结构以及水凝胶表面和内部形态，这些分析结果是取代度（DS）和水凝胶制备中使用的初始含水量的函数。MIP分析表明，整体网络明显为大孔结构，孔径范围为0.065至10微米。正如预期的那样，平均孔径随着DS的增加和初始含水量的降低而减小。此外，孔隙率值范围为75%至90%，这表明这些水凝胶具有相互连接的孔隙结构。氮吸附分析表明，dexT70 - VA水凝胶的比表面积通过增加DS或降低水凝胶的初始含水量而增加。SEM结果显示，DS较低的水凝胶表面呈现多孔结构或覆盖孔隙的聚合物“皮层”，而DS较高的水凝胶完全是多孔的。此外，内部形态根据水凝胶的DS和初始含水量而变化。最后，还使用Flory - Rehner开发的理论模型从水凝胶的溶胀中确定了平均孔径。将SEM和MIP结果与通过Flory - Rehner平衡溶胀理论获得的结果进行比较表明，这种方法高度低估了平均孔径。
