A solution study of silica condensation and speciation with relevance to in vitro investigations of biosilicification.
A solution study of silica condensation and speciation with relevance to in vitro investigations of biosilicification.
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DOI：
10.1021/jp101347q
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发表时间：
2010-08-12
影响因子：
3.3
通讯作者：
Perry, Carole C.
中科院分区：
文献类型：
--
作者：
Belton, David J.;Deschaume, Olivier;Patwardhan, Siddharth V.;Perry, Carole C.
生物硅具有温和的合成条件、高水平的组织和功能，是材料科学家和生物学家的奇迹和灵感来源。为了了解这些生物材料是如何形成的，并将这些知识应用于新型生物启发材料的产生，需要对在生物相关条件下形成的材料进行详细研究。在这方面的贡献，数据从一个详细的研究使用模型生物启发的二氧化硅前体（硅儿茶酚复合物，SCC）的二氧化硅形态和缩合。硅复合物在中性pH条件下快速可控地解离为原酸的明确定义的亚稳溶液。硅钼（蓝）配合物的形成被用来监测和研究不同阶段的柠檬酸缩合。与此同时，硅钼（黄色）络合物形成的速率，与存在的物种的数学建模被用来遵循的解决方案形态的聚碳酸酯。从这两种测定法获得的结果相关性良好，并且可以鉴定单体聚乳酸、三聚体聚乳酸和不同类别的低聚乳酸和二氧化硅核，并且可以测定它们在二氧化硅缩合的早期阶段的稳定期。在273- 323 K的温度范围内进行的实验中，三聚体形成的活化能为77 kJ·mol-1。在273-293 ± 1 K温度范围内，单体与聚碳酸酯的正、逆缩合反应的活化能分别为55.0和58.6kJ·mol-1。当温度高于293 K时，这些能量分别降低到6.1和7.3 kJ·mol−1，表明主要的缩合机制可能发生了变化。测定了pH值对缩合速率的影响。三聚体形成的表观三级速率常数与pH（4.7-6.9 ± 0.1）之间存在直接相关性，而可逆的一级速率值在环中性pH下达到一个平台。这些不同的行为参照普遍接受的二氧化硅缩合机理进行了讨论，其中阴离子硅酸盐溶液物种是缩合过程的中心。本文提出的结果支持使用的前体，如硅儿茶酚复合物在体外生物硅化的研究。需要进一步详细的实验来增加我们对特定生物分子二氧化硅相互作用的理解，这些相互作用最终会产生我们在周围世界中观察到的复杂，精细的硅质结构。
With both mild synthesis conditions, a high level of organisation and functionality, biosilicas constitute a source of wonder and inspiration for both materials scientists and biologists. In order to understand how such biomaterials are formed and to apply this knowledge to the generation of novel bioinspired materials, a detailed study of the materials, as formed under biologically relevant conditions, is required. In this contribution, data from a detailed study of silica speciation and condensation using a model bio-inspired silica precursor (silicon catechol complex, SCC) is presented. The silicon complex quickly and controllably dissociates under neutral pH conditions to well-defined, metastable solutions of orthosilicic acid. The formation of silicomolybdous (blue) complexes was used to monitor and study different stages of silicic acid condensation. In parallel, the rates of silicomolybdic (yellow) complex formation, with mathematical modelling of the species present was used to follow the solution speciation of polysilicic acids. The results obtained from the two assays correlate well and monomeric silicic acid, trimeric silicic acids and different classes of oligomeric polysilicic acids and silica nuclei can be identified and their periods of stability during the early stages of silica condensation measured. For experiments performed at a range of temperatures (273–323K) an activation energy of 77kJ·mol−1 was obtained for the formation of trimers. The activation energies for the forward and reverse condensation reactions for addition of monomers to polysilicic acids (273–293 ± 1K) were 55.0 and 58.6kJ·mol−1 respectively. For temperatures above 293K, these energies were reduced to 6.1 and 7.3 kJ·mol−1 indicating a probable change in the prevailing condensation mechanism. The impact of pH on the rates of condensation were measured. There was a direct correlation between the apparent third order rate constant for trimer formation and pH (4.7–6.9 ± 0.1) while values for the reversible first order rates reached a plateau at circumneutral pH. These different behaviours are discussed with reference to the generally accepted mechanism for silica condensation in which anionic silicate solution species are central to the condensation process. The results presented in this paper support the use of precursors such as silicon catecholate complexes in the study of biosilicification in vitro. Further detailed experimentation is needed to increase our understanding of specific biomolecule silica interactions that ultimately generate the complex, finely detailed siliceous structures we observe in the world around us.
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影响因子：
--
作者：
ASHLEY, KD;INNES, WB
通讯作者：
INNES, WB
DOI：
10.3891/acta.chem.scand.21-2503
发表时间：
1967-01-01
期刊：
ACTA CHEMICA SCANDINAVICA
影响因子：
--
作者：
BILINSKI, H;INGRI, N
通讯作者：
INGRI, N
影响因子：
64.8
作者：
Cha, JN;Stucky, GD;Deming, TJ
通讯作者：
Deming, TJ
影响因子：
4.2
作者：
Currie, Heather A.;Perry, Carole C.
通讯作者：
Perry, Carole C.
影响因子：
15
作者：
ALEXANDER, GB
通讯作者：
ALEXANDER, GB