pH-Dependent Schemes of Calcium Carbonate Formation in the Presence of Alginates
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- 作者：Ashit Rao ; Patricio Vásquez-Quitral ; María S. Fernández ; John K. Berg ; Marianela Sánchez ; Markus Drechsler ; Andrónico Neira-Carrillo ; José L. Arias ; Denis Gebauer ; Helmut Cölfen
- 刊名：Crystal Growth & Design
- 出版年：2016
- 出版时间：March 2, 2016
- 年：2016
- 卷：16
- 期：3
- 页码：1349-1359
- 全文大小：643K
- ISSN：1528-7505
文摘
From recent studies on bone and shell formation, the importance of polysaccharides in biomineralization processes is gradually being recognized. Through ion-complexation and self-assembly properties, such macromolecules have remarkable effects on mineralization. However, their influences on the different regimes of crystallization including the interactions with precursor species are unclear. The present study therefore addresses calcium carbonate mineralization in the presence of alginates, a class of linear copolymeric saccharides composed of β-1,4 linked class="smallcaps">d-mannuronic and class="smallcaps">l-guluronic acid. During mineralization, this biopolymer is found to exert pH-dependent control over mineralization pathways in terms of the stability of prenucleation clusters, inhibitory effect toward nucleation and initially formed postnucleation products. Remarkably in the presence of this macromolecular additive, either amorphous or crystalline vaterite particles can be selectively nucleated in a pH-dependent manner. This is validated by electron microscopy wherein vaterite particles are intimately associated with alginate assemblies after nucleation at pH 9.75. At lower pH, aggregates of amorphous particles are formed. Thus, in addition to the general focus on biochemical properties of additives, solution pH, a physiologically fundamental parameter significantly alters the scheme of mineralization.