ENGINEERING RESEARCH EQUIPMENT: A Combined Fluorescence Optical Microscope/Non-Contact Atomic Force Microscope for Monolayer and Multilayer Studies

扫描探针显微镜的新成像模式——非接触、敲击、摩擦或侧向力模式——使得以前很难或不可能用OseeO成像的各种表面成为可能。除了简单的表面形貌外，这些新的成像模式还利用了表面化学、摩擦、顺应性、电荷等方面的变化来提高图像对比度。对于许多这些模式，AFM尖端要么不与样品表面接触，要么轻轻敲击样品表面。因此，与传统的接触模式AFM相比，更柔软的表面可以成像，并且较少倾向于重新排列松散支撑的材料。提出通过购买Nanoscope多模AFM和必要的附件来升级现有的接触式AFM，实现非接触式和轻叩式成像。这些新的成像模式将应用于表面活性剂、脂质和蛋白质的自组装和模式形成的正在进行的研究。这些新的成像模式被证明在检测复杂的流体界面、表面活性剂、蛋白质和聚合物的吸附、膜中的横向相分离、蛋白质的定位和扩散、自组装膜的动力学和结构等方面非常有用。这种新的仪器也将使我们能够表征更真实的模型膜表面的力测量与表面力仪器。为了完全实现新的成像模式，有必要在使用AFM之前确定表面上感兴趣的区域。最好的方法是将AFM与能够进行荧光成像的高分辨率光学显微镜相结合。荧光显微镜是在微米水平上识别脂质结构域、特定蛋白质（通过抗体标记）、吸附等的最佳方法之一。将荧光图像与分子分辨率AFM图像直接关联将是一项重大进展。一种定制的荧光显微镜最近被用来检查空气-水界面的单层。在AFM成像之前和期间，可以构造一个非常类似的仪器来检查衬底上的薄膜。有了这种综合能力，首席研究员应该能够定位蛋白质、相边界等，并将它们与它们对双层性质的宏观影响联系起来。在空气-水界面上由各种脂质混合物形成的自发模式转移到用作光刻式模板的基底上，由吸附物质混合物的竞争性自组装形成的模式，以及表面矿化的初始阶段，也可以研究。＊＊＊

9622506 Zasadzinski New modes of imaging with scanning probe microscopes - non-contact, tapping, and friction or lateral force modes - have made it possible to image a variety of surfaces that had previously been difficult or impossible to OseeO. These new imaging modes take advantage of variations in surface chemistry, friction, compliance, charge, etc. to develop image contrast in addition to simple surface topography. For many of these modes, the AFM tip is either not in contact with or is gently tapped on the sample surface. Hence, much softer surfaces can be imaged than with conventional contact mode AFM and there is less tendency to rearrange loosely supported materials. It is proposed to upgrade the current contact mode AFM by purchasing a Nanoscope Multimode AFM and the necessary accessories to do non-contact and tapping mode imaging. These new imaging modalities will be applied to the ongoing studies of self-assembly and pattern formation in surfactant, lipid and proteins. These new imaging modes are proving to be extremely useful in examining complex fluid interfaces, surfactant, protein, and polymer adsorption, lateral phase separation in membranes, protein localization and diffusion, the kinetics and structures of self-assembled films, etc. This new apparatus will also allow us to characterize more realistic model membrane surfaces for force measurements with the Surface Forces Apparatus. To fully implement the new imaging modes, it is necessary to identify areas of interest on the surface prior to engaging the AFM. The best way to do this is by coupling the AFM to a high resolution optical microscope capable of fluorescence imaging. Fluorescence microscopy is one of the best ways of identifying lipid domains, specific proteins (via antibody labeling), adsorption etc. at the micron level. It would be a major advance to directly correlate the fluorescence images with molecular resolution AFM images. A custom fluorescence microscope has recently been built for examin ing monolayers at the air-water interface. A very similar instrument can be constructed to examine thin films on substrates prior to and during AFM imaging. With this combined capability, the principal investigator should be able to localize proteins, phase boundaries, etc. and correlate them with their macroscopic effects on bilayer properties. The transfer of the spontaneous patterns formed by various lipid mixtures at the air-water interface to substrates to be used as lithographic-style templates, the patterns formed by competitive self-assembly of mixtures of adsorbing species, and the initial stages of mineralization of surfaces, can also be studied. ***