Crystallisation in Confinement - A Biological Perspective

生物系统的组织和功能是基于分隔的，即过程发生在小体积而不是大容量溶液中。生物舱的一个简单例子是细胞，它本身可以包含许多更小的舱。越来越明显的是，以这种方式限制反应可以通过改变分子之间及其环境相互作用的方式来极大地影响生物和化学反应的机制和产物。这个项目将专注于生物过程的一个非常重要的类别-生物矿化-这是贝壳、骨骼和牙齿等矿物质结构的形成。人们对了解自然如何控制结晶来产生这种类型的材料有相当大的兴趣。尽管生物矿物是在温和的反应条件下产生的，但它们的性能不仅可以与混凝土等工程材料相提并论，而且实际上可以超过这些材料。这项提案中的研究将调查限制如何影响结晶，以及自然如何利用这一点来生产如此非凡的材料。到目前为止，旨在了解自然如何控制矿物形成的研究集中在有机大分子的作用上。此外，尽管生物矿化总是在有限的体积内进行，但旨在模拟这些过程的实验通常是在散装溶液中进行的。虽然有机分子当然很重要，但限制也很可能对这些结晶过程产生重大影响。事实上，有许多生物结晶现象，例如在骨形成过程中，钙磷晶体在胶原纤维中沉淀，这不能用大量溶液的结晶来充分描述。初期工作将侧重于少量碳酸钙和磷酸钙的沉淀。然后，研究计划将扩展到研究限制对一系列其他矿物结晶的影响。虽然很明显，在很大范围的长度尺度上的限制可以强烈地影响晶体的成核和生长，但除了冻结现象之外，这些影响还知之甚少，而且还无法预测。所进行的研究将使我们更好地了解受限体积中的结晶作用，从而使我们能够使用限制作用来控制结晶作用，并在合成系统中从中受益。事实上，有许多技术应用依赖于在有限体积内生长晶体，例如制造纳米材料，包括纳米线和纳米管阵列，一般模板工艺，药物输送系统和植入物。限制条件下的结晶作用在自然界也很普遍，除了生物矿化过程外，还包括风化和冻胀等事件--这些事件会给环境和技术带来巨大的土木工程成本。这项拟议的研究显然与许多学科的基础研究和技术都有很大的相关性。

The organisation and function of biological systems is based on compartmentalisation, where processes occur within small volumes rather in bulk solution. A simple example of a biological compartment is a cell, which itself can contain many smaller compartments. It is becoming increasingly obvious that confining reactions in this way can dramatically affect the mechanisms and products of biological and chemical reactions by changing the way that molecules interact with each other and their environment.This project will focus on one very important category of biological processes - biomineralisation - which is the formation of mineral-based structures such as seashells, bones and teeth. There is considerable interest in understanding how Nature controls crystallisation to produce materials of this type. Although biominerals are produced under mild reaction conditions, they often exhibit properties which can not only equal but actually surpass those of engineering materials such as concrete. The research in this proposal will investigate how confinement affects crystallisation, and how Nature exploits this to produce such remarkable materials. To-date, research directed towards understanding how Nature controls the formation of minerals has concentrated on the role of organic macromolecules. Further, although biomineralisation invariably occurs within restricted volumes, experiments aiming to mimic these processes are typically carried out in bulk solution. While organic molecules are certainly important, it is very likely that confinement also has a significant affect on these crystallisation processes. Indeed, there are many biogenic crystallisation phenomena, such as the precipitation of calcium phosphate crystals in collagen fibres during bone formation, which cannot be adequately described in terms of crystallisation from bulk solution. Initial work will focus on the precipitation of calcium carbonate and calcium phosphate in small volumes. The research programme will then be extended to investigate the effect of confinement on the crystallisation of a range of other minerals. While it is clear that confinement over a wide range of length scales can strongly affect crystal nucleation and growth, with the exception of freezing phenomena, these effects are poorly understood and as yet unpredictable. The research conducted will lead to a greater understanding of crystallisation in restricted volumes, and will therefore enable us to use confinement to control crystallisation, and to profit from it in synthetic systems. Indeed, there are many technological applications which rely upon crystal growth within constrained volumes such as the fabrication of nano-materials including nanowires and nanotube arrays, general templating processes, drug delivery systems and implants. Crystallisation in confinement is also widespread in Nature, and in addition to biomineralisation processes, includes events such as weathering and frost heave - which occur with great cost to civil engineering the environment and technology. The proposed research is clearly of great relevance to both fundamental research and technology across many disciplines.