Fluorescence Spectrophotometer to Investigate Nanostructures at Interfaces

Somasundaran, ponisseril，哥伦比亚大学“荧光分光光度计研究界面纳米结构”该项目是为纽约哥伦比亚大学Langmuir胶体和界面中心采购荧光光谱仪，用于跨学科研究团队的研究，研究新型纳米结构及其在各种界面上的动态行为。将使用该仪器的主要研究人员包括Chasin教授（生物系），Gryte教授（化学系）。Somasundaran教授（地球与环境）工程)和Turro教授（化学系）。纳米级表面活性剂和聚合物的吸附用于改性固体的表面性质，并在许多工业过程中得到应用，如絮凝/分散、沉积、涂层、提高石油采收率和浮选。在这些情况下，有效利用吸附不仅取决于吸附量，还取决于吸附层的纳米结构，即吸附物质的构象和取向。目前关于被吸附物质的构象方面的信息很少，主要是由于缺乏可靠的原位技术。他们早期的工作重点是通过研究吸附密度、zeta电位、润湿性和量热效应来了解表面活性剂、聚合物和蛋白质吸附的物理化学机制。这样的研究有助于产生吸附层结构的机械图像。最近，Turro， Somasundaran和Gryte合作使用荧光光谱和电子自旋共振光谱（ESR）来探测颗粒，脂质体，植入物等上吸附的表面活性剂和聚合物层。这些研究证明了荧光光谱在研究吸附层的纳米结构方面的潜力。有了这种新的荧光仪器，在亚分子水平（纳米尺度）的界面上研究物种的构象方面就有了前所未有的机会。更广泛的技术影响：该仪器将用于全面了解表面活性剂和聚合物/蛋白质的相互作用，特别是吸附层和胶体聚集体的纳米结构以及不同参数对结构的影响。有关溶解和吸附物质的构象及其动态行为的知识将有助于开发对污染物、生物制剂和参数（如pH、温度和离子强度）扰动有响应的智能材料。该仪器将用于众多项目，其中大多数旨在提高我们对分子组装系统的理解，对基础科学和技术进步非常重要。由于该仪器由几个研究人员共享，并将用于不同学科的几个独立项目，因此很可能会有大量学生和博士后使用该分光光度计。这些仪器还将为本科生提供培训机会。

Somasundaran, PonisserilColumbia University" Fluorescence Spectrophotometer to Investigate Nanostructures at Interfaces."This project is for the procurement of a Fluorescence Spectrometer, for the Langmuir Center for Colloid and Interfaces of Columbia University, New York, for the research of an interdisciplinary research team, investigating novel nanostructures and their dynamic behavior at various interfaces. The principal investigators who will use this instrument include Prof. Chasin (Biology Dept.), Prof. Gryte (Dept. of Chem. Eng.), Prof. Somasundaran (Earth and Env. Eng.) and Prof. Turro (Chemistry Dept.). Adsorption of nanoscale surfactants and polymers is used for the modification of the surface properties of solids and finds application in many industrial processes such as flocculation/dispersion, deposition, coatings, enhanced oil recovery and flotation. Efficient use of adsorption in these cases depends not only on the amount adsorbed but also on the nano structure of the adsorbed layer in terms of the conformation and orientation of the adsorbed species. Currently there is very little information on conformational aspects of the adsorbed species, mainly due to lack of reliable in-situ techniques. Their earlier work focused on understanding the physico-chemical mechanisms of adsorption of surfactants, polymers and proteins by studying adsorption density, zeta potential, wettability and calorimetric effects. Such investigations have helped in generating a mechanistic picture of the structure of the adsorbed layers. More recently, Turro, Somasundaran and Gryte have collaborated in using fluorescence spectroscopy along with electron spin resonance spectroscopy (ESR) to probe adsorbed surfactant and polymer layers on particles, liposomes, implants etc. These studies have demonstrated the potential of fluorescence spectroscopy to investigate the nano-structure of adsorbed layers. With this new fluorescence instrumentation available, there is an unprecedented opportunity to investigate the conformational aspects of species at interfaces on a sub molecular level (nanoscale). Broader Technical Impact: This instrument will be used to develop a full understanding of the interactions of surfactants and polymers / proteins, particularly the nano-structures of adsorbed layers and colloidal aggregates and the effects of different parameters on the structure. Knowledge about the conformation of the dissolved and adsorbed species and their dynamic behavior will prove useful for developing smart materials responsive to the presence of contaminants, bioagents and perturbations in parameters such as pH, temperature and ionic strength. The instrument will be used ton a multitude of projects, most of which are aimed at improving our understanding of molecularly assembled systems and are important to basic science and advance in technologies. Because the instrument is being shared among several researchers and will be used on several independent projects in different disciplines, it is likely that the spectrophotometer will be used by a large number of students and postdoctoral fellows. The instruments will also offer training opportunities for undergraduates.