Control over Different Crystallization Stages of CaCO3-Mediated by Silk Fibroin

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• 作者：Ting Wang ; Renchao Che ; Wentao Li ; Ruixin Mi ; Zhengzhong Shao
• 刊名：Crystal Growth & Design
• 出版年：2011
• 出版时间：June 1, 2011
• 年：2011
• 卷：11
• 期：6
• 页码：2164-2171
• 全文大小：958K
• 年卷期：v.11,no.6(June 1, 2011)
• ISSN：1528-7505

文摘

The crystallization process of CaCO₃-mediated by the addition of silk fibroin at different crystalline stages was examined. During earlier stages of crystallization, time-resolved transmission electron microscopy (TEM) was applied to demonstrate that the crystallization of an amorphous precursor was based on randomly oriented domains. Different addition times of silk fibroin primarily led to two kinds of morphology of CaCO₃, that is, lens-like and multilayered vaterite. Additionally, the thickness or number of layers of such vaterite would increase with the delay of silk fibroin addition, ascribing to the control of silk fibroin over different basic units during the aggregation and reorientation process. It was found that those squeezed-out silk fibroins, which probably resulted from the relatively weak interaction between silk fibroin chains and (001) plane of vaterite phase during the crystallization process could lead to the formation of oblate aggregates via vectorial assembly of units with consistent orientation (nanoparticle for lens-like vaterite or flake for layered vaterite) and inhibition to the growth of (001) faces of fused intermediates. For comparison, the crystallization process of CaCO₃ regulated by poly (acrylic acid) (PAA) was observed by cryoSEM, presenting a 鈥渟tepwise aggregation鈥?pathway to form spherical polycrystals which may be attributed to strong electrostatic interaction between carboxyl groups in PAA chains and nanoparticles. Therefore, the extent of binding affinity between organic and inorganic substances was proposed to be relevant to the reconstructuring process and the morphologies of final product.