Fluorescence imaging characterisation of silicates

目的：这个多学科项目是研究使用光漂白后荧光恢复（FRAP）显微镜和相关技术来表征纳米结构在硅酸盐液体中的扩散，这影响了这些液体在许多应用中的功效，包括多孔二氧化硅的制造。控制这些液体中胶体种类的大小和数量的硅酸盐制造条件知之甚少，主要是因为缺乏适当表征所得硅酸盐的技术。背景：尽管FRAP通常用于生物系统的研究，但PQ公司几年前的可行性评估表明，FRAP为更好地了解硅酸盐液体提供了一种很有前途的方法。该项目的成功结果将提供一个比较硅酸盐的价值数字，这将大大提高对硅酸盐制造、结构和性能之间关系的理解。该项目建立在PQ和Strathclyde的光物理小组之间的长期合作基础上，该小组在其他成果中提出了一种新的硅酸盐纳米颗粒计量方法[1,2]。FRAP的工作原理要求对微观区域进行光漂白，并记录由于荧光物质扩散重新进入所研究区域而导致的瞬态荧光强度恢复。目前，合作公司内部没有FRAP能力，但通过该项目，FRAP系统将在Strathclyde使用PQ提供的样品进行组装、开发和测试。光物理组拥有构建和表征仪器所需的光学设计，荧光和数据分析专业知识。该集团还拥有广泛的互补仪器，以比较结果和优化FRAP性能。一旦开发和验证，该仪器可以复制到PQ现场使用。作为项目的一部分，学生将获得在英国PQ工作的宝贵工业经验，这些经验将对优化仪器性能至关重要。项目目标将通过完成几个关键目标（项目可交付成果）来实现：FRAP显微镜系统的组装包括激光激发，显微镜组件，光学耦合，同步电子，光子检测和相关的图像分析软件。2. 在酸性和碱性ph范围内评价FRAP的最佳荧光染料。3 .在表征良好和标准的硅酸盐溶胶上对FRAP系统进行测试和校准，包括与光散射、荧光各向异性和荧光相关光谱等其他方法进行比较。模拟硅酸盐颗粒的扩散和观察到的FRAP和其他补充技术使用（分子动力学，激发态动力学，实验设计）。确定最佳拟合模型并优化实验程序。5. 硅酸盐特征和改进的FRAP技术与可能影响硅酸盐中胶体种类的类型、数量和大小的工艺变量（例如，铁、铝、钙、镁的存在）的关联数据。PQ将以系统的方式提供制造条件已改变的硅酸盐样品。6. 研究样品的稳定性和老化（所有的硅酸盐都是亚稳的）。7. 使用FRAP技术进一步提高对硅酸盐的制造，其结构以及两者如何影响产品功效的理解。

The Aim: This multidisciplinary project is to investigate the use of fluorescence recovery after photobleaching (FRAP) microscopy and related techniques to characterise the diffusion of nm structures in silicate liquors, which influences the efficacy of these liquors in many applications including the manufacture of porous silicas. The silicate manufacturing conditions that control the size and number of colloidal species in these liquors is poorly understood, largely because of a lack of techniques to properly characterise the resulting silicates.Background: Although FRAP is more usually used for the study of biological systems, a feasibility assessment by PQ Corporation some years ago suggested FRAP offers a promising approach to better understanding silicate liquors. A successful outcome of the project would deliver a figure of merit with which to compare silicates that would significantly improve understanding of the relationships between silicate manufacture, structure and performance. The project builds on a long-standing collaboration between PQ and Strathclyde' Photophysics Group which led, amongst other outcomes, to a new method of silicate nanoparticle metrology [1,2]. The operating principle of FRAP requires photobleaching of a microscopic area and recording the transient fluorescence intensity recovery as a consequence of the diffusion of fluorescent species re-entering the area under study. At present there is no FRAP capability in-house at the collaborating company but, through this project, a FRAP system will be assembled, developed and tested at Strathclyde using samples that PQ will provide. The Photophysics Group has the optical design, fluorescence and data analysis expertise required to construct and characterise the instrument. The Group also possesses an expansive range of complementary instrumentation to compare results and optimise the FRAP performance. The instrument can be replicated for on-site use at PQ once developed and proven. The student will gain valuable industrial experience working at PQ in the UK as part of the project, experience that will be essential in optimising instrument performance. The aim of the project will be achieved by completing several key objectives (project deliverables):1. The assembly of a FRAP microscopy system to include laser excitation, microscope assembly, optical couplings, synchronisation electronics, photon detection and associated image analysis software. 2. Assessment of the optimum fluorescence dyes for FRAP over a range of acidic and alkaline pH.3. Testing and calibration of the FRAP system on well-characterised and standard silicate sols including comparison with other methods such as light scattering, fluorescence anisotropy and fluorescence correlation spectroscopy.4. Modelling the silicate particles diffusion and the observables detected by FRAP and other complementary techniques used (molecular dynamics, excited-state kinetics, experiment design). Determining the best-fit models and optimisation of the experimental procedure. 5. Silicate characterisation and correlating data from the improved FRAP technique with process variables (e.g. presence of Fe, Al, Ca, Mg) that may influence the type, number and size of colloidal species present in the silicate. PQ will provide silicate samples where manufacturing conditions have been altered in a systematic way. 6. Studies on samples stability and ageing (all the silicates will be metastable). 7. Using the FRAP technique to further improve understanding of the manufacture of silicates, their structure and how both of these influence product efficacy.