Cell Endoscopy with Nanowire Probe

描述(申请人提供)：在这个R21项目中，我们计划开发一种用于单细胞内窥镜检查的高度集成和高灵敏度的纳米线探针平台。在这个平台的中心是一个集成的柔性纳米线，它位于近场扫描光学显微镜(NSOM)探针的尖端。该计划将建立在我们在纳米结构合成/组装、系统集成和基于纳米线的光子学方面的广泛专业知识的基础上。我们广泛的能力和专业知识将使我们处于独特的地位，实现潜在的突破，并在单细胞成像和探测方面开辟新的可能性。这种柔性纳米线探针的开发将使我们能够监测单个活细胞内的体内生物过程，并将极大地提高我们对细胞功能、细胞内生理过程、细胞信号途径的基本理解，从而使细胞生物学发生革命性的变化。我们将成功开发一个NSOM-纳米线探针的原型，并展示其在细胞内成像和探测方面的原理证明应用。我们将开发和优化组装这些细胞内窥镜纳米线探针的策略，即直接纳米操纵和将纳米线连接到NSOM探针上。在这项研究中，我们将测试两种类型的纳米线作为亚波长光波导。一种是像SnO2这样的常规介质材料，另一种是像KNbO_3这样具有强非线性光学性质的材料。与这些建议的细胞内窥镜探头相关的几个关键特征：1.侵入性最小。所使用的纳米线的直径一般在100 nm以下，并且具有高纵横比。这一结构特征确保了拟议平台的非侵入性。2.灵活性高。这些纳米线非常灵活，但在机械上却很坚固。这些纳米线的扭曲和弯曲不会造成显著的光传输损耗，极大地简化了此类探针在单细胞成像中的应用。3.高折射率。因此，即使在高折射率生理液体和/或活细胞环境中，这些纳米线也是有效的亚波长光波导。4.高局域激发和检测方案的消逝波光学传感原理。由于这些纳米线的亚波长光波导性质，这些纳米线的探测体积可以限制在纳米线的最顶端(即低至皮微升和毫微升)。5.具有非线性光学转换能力。将非线性光学纳米线应用到所提出的探测平台中，将引入两个重要的特征：亚波长波导和频率转换能力。我们将能够在纳米线的一端输入红外线，并在另一端使用可见光或紫外光输出来进行细胞成像/探测。在现实的生理环境中，使用红外作为输入束将再次极大地有利于整个成像过程。这种新颖的纳米线探针有望在极大地增强三维空间分辨率和时间分辨率的同时进行细胞内成像。此外，这些纳米线探针还可以用于从单个活细胞中点传递或提取化学物质(蛋白质/DNA)，与传统的传递/提取方法相比，空间分辨率大大提高。

DESCRIPTION (provided by applicant): In this R21 program, we propose to develop a highly-integrated and highly-sensitive nanowire probe platform for single cell endoscopy. At the center of this platform lies the integrated flexible nanowire on the tip of a near- field scanning optical microscopy (NSOM) probe. This program will be built upon our extensive expertise in nanostructure synthesis/assembly, systems integration and nanowire based photonics. Our extensive capabilities and expertise will put us in a unique position to achieve potential breakthroughs and open up new possibilities in single cell imaging and probing. Developing of such flexible nanowire probes would enable us to monitor in-vivo biological processes within single living cells and will greatly improve our fundamental understanding of cell functions, intracellular physiological processes, cellular signal pathway, and thereby revolutionalizes cell biology. We will successfully develop a prototype for NSOM-nanowire probe and demonstrate its proof-of-principle applications for intracellular imaging and probing. We will develop and optimize strategies to assemble these cell endoscopy nanowire probes, i.e., direct nanomanipulation and attachment of nanowires onto NSOM probes. We will test two types of nanowires as sub-wavelength optical waveguides for this study. One is conventional dielectric materials such as SnO2, the other one being materials with strong non-linear optical properties, such as KNbO3. There are several key features associated with these proposed cell endoscopy probes: 1. Minimal invasiveness. The nanowires used will generally have diameters of sub-100 nm and with high aspect ratio. This structural feature ensures the non-invasiveness of the proposed platforms. 2. High flexibility. These nanowires are highly flexible and yet mechanically robust. The twisting and bending in these nanowires will not cause significant optical propagation loss, and greatly ease the application of such probes in single cell imaging. 3. High refractive index. As a result, these nanowires are efficient sub-wavelength optical waveguides even in high-index physiological liquids and/or living cell environments. 4. Evanescent wave optical sensing principle with highly localized excitation and detection scheme. Because of the subwavelength optical waveguiding nature of these nanowires, the probe volume of these nanowires can be limited to the very tip of the nanowires (i.e. down to pico- and femtoliter). 5. Nonlinear optical conversion capability. This application of the nonlinear optical nanowires into the proposed probe platforms will introduce two important features: subwavelength waveguiding and frequency conversion capability. We will be able to input IR beam at one end of the nanowires and use the visible or UV output on the other end to do the cell imaging/probing. The use of IR as input beam would again greatly benefit the entire imaging process in realistic physiological environments. Such novel nanowire probes promise intracellular imaging with greatly enhanced 3-dimensional spatial resolution as well as temporal resolution. In addition, these nanowire probes could also be used to spot- delivery or extraction of chemicals (proteins/DNAs) from single living cells with much improved spatial resolution as compared to conventional delivery/extraction methods.