Nanoscale chemical imaging: Tools and techniques for localised infrared spectroscopy of nanostructured polymers and biomaterials.

从本质上讲，所有生物都是由纳米级的自组装形成的。化学相互作用控制着单个分子的物理顺序，将它们结合起来构建有序的结构，形成宏观生物体的基础。因此，形成的整体结构可以看作是由分子水平的化学规划产生的。尽管这些过程在自然界已经发生了数十亿年，但科学最近才开始赶上来。人工自组装材料的研究，无论是完全合成的还是受生物启发的，是纳米科学更广泛领域中一个非常活跃的研究领域。这类材料被广泛认为是一系列未来技术的关键。同时，纳米级结构的限制尺寸往往导致化学过程以与块状材料明显不同的方式进行，从而提供了一种控制的方法，例如，控制某些疾病的潜在分子原因。研究这种纳米尺度的结构，直径可能只有几十个原子，对科学仪器提出了新的挑战。普通显微镜根本无法看到如此小的结构，因为光的波长是这些尺寸的许多倍。虽然电子显微镜被广泛使用，但最近发展的一种技术是原子力显微镜（AFM）。AFM使用一个精细的探针，在某些情况下，探针的尖端直径只有几个原子，来建立一个样品的机械轮廓图像。实际上，AFM是感觉而不是看到表面。探针尖端的小尺寸使得原子力显微镜可以很容易地解决纳米尺度的特征，并且它们已经迅速成为该领域普遍存在的研究工具。然而，放弃光学显微镜有一个主要的缺点。通过吸收或发射光来检测特定化合物的光谱学在原子力显微镜上是不可能的。许多参与纳米级自组装的分子在红外光谱中具有特征指纹。因此，将红外光谱技术与原子力显微镜的纳米级成像能力结合起来将具有巨大的价值。这些技术将使研究人员对单个纳米结构中的化学过程有重要的新见解，从而使该领域取得重大进展。这个项目的目的就是开发这样一种仪器。实现这一目标的早期工作受到了限制，因为缺乏合适的红外激光器，无法精确地调整波长，以收集化合物的光谱指纹。在这个项目中，基于所谓的非线性光学技术，新型的类激光光源将被开发出来，这种技术可以有效地将激光输出从具有所需调谐特性的波长转移到不具有所需调谐特性的红外波长。为了测试所开发的技术，将研究几个纳米尺度的化学过程。第一个是纳米级控制某些蛋白质的自然自组装，这些蛋白质被认为与阿尔茨海默病的进展有关。第二项研究将检查设计蛋白自组装过程中发生的化学变化，这可能构成人工组织的基础。最后，将研究形成功能表面的结构的行为，这些结构会根据局部化学环境改变其物理性质。在所有情况下，除了测试项目中开发的新分析技术外，预计将在研究中的系统中获得其他方法无法获得的新见解。

All living things are, in essence, formed by nanoscale self-assembly. Chemical interactions control the physical ordering of individual molecules, combining them to build ordered structures that form the basis of macroscopic organisms. The overall structures formed can, therefore, be seen as arising from molecular-level chemical programming . Although these processes have been occurring in nature for billions of years, science has recently started to catch up. The investigation of artificial self-assembled materials, both wholly synthetic and biologically inspired, is an extremely active area of research within the wider field of nanoscience. Such materials are widely recognised as key to a range of future technologies. At the same time, the restrictive dimensions of nanoscale structures often cause chemical processes in to proceed in a markedly different manner to those in bulk materials, thus offering a way to control, for example, the underlying molecular causes of some diseases.Studying structures of such nanoscale dimensions, perhaps only a few tens of atoms in diameter, presents new challenges for scientific instrumentation. Ordinary microscopes are fundamentally incapable of seeing such small structures due to the wavelength of light being many times these dimensions. While electron microscopes are widely used, a more recently developed technique is the atomic force microscope (AFM). An AFM uses a fine probe, in some cases having a tip only a few atoms in diameter, to build a mechanically profiled image of a sample. Effectively the AFM feels rather than sees the surface. The small probe tip dimensions allow AFMs to easily resolve nanoscale features, and they have rapidly become ubiquitous research tools in the field.However, abandoning the light microscope has a major disadvantage. Optical spectroscopy, detecting particular chemical compounds by their absorption or emission of light, is not possible with an AFM. Many molecules involved in nanoscale self assembly have characteristic spectroscopic fingerprints in the infrared. It would, therefore, be of immense value to combine the techniques of infrared spectroscopy with the nanoscale imaging capabilities of the AFM. Such techniques would give researchers important new insights into the chemical processes at work in individual nanostructures, allowing significant advances in the field. It is the aim of this project to develop precisely such an instrument.Promising early work to achieve this is limited by the lack of suitable infrared lasers able to precisely tune their wavelength far enough to collect the spectroscopic fingerprint of chemical compounds. In this project, novel laser-like sources will be developed, based on so-called nonlinear optical techniques, which effectively shift the output of a laser from wavelengths where the desired tuning properties are available to infrared wavelengths, where they are not.To test the techniques developed, several nanoscale chemical processes will be studied. The first is nanoscale control of the natural self-assembly of certain proteins thought to be associated with the progress of Alzheimer's disease. The second will examine chemical changes occurring during self-assembly of designer proteins, which may form the foundation of artificial tissues. Finally, the behaviour of structures forming functional surfaces that change their physical properties in response to the local chemical environment will be investigated. In all cases, as well as testing the new analytical techniques developed in the project, it is anticipated that new insights, unobtainable by other methods, will be gained into the systems under study.