Feasibility study: endoscopic surface-enhanced Raman spectroscopy (SERS) for in s

描述（由申请人提供）：分子成像是一项新兴技术，通过无创方式检测分子特征，可以提供活体组织物理外观以外的信息。该技术对诊断、活检或手术指导以及药物临床前和临床试验的优化非常有用。在各种分子成像技术中，拉曼光谱技术尤其令人感兴趣，因为它安全、廉价、不含试剂，最重要的是，它能够同时检测多个分子。然而，普通的拉曼光谱有明显的缺点，即灵敏度低。将纳米金属结构放置在分子附近可以极大地增强拉曼信号。利用这种表面增强拉曼光谱（SERS）在分子成像方面具有很大的潜力。然而，它只在外部拉曼显微镜的设置中被证明，并将纳米颗粒注射到小动物体内。虽然这些演示显示了原位SERS的前景，但要在临床环境中实施该方法，它必须与内窥镜检查结合使用，以绕过光的穿透限制。作为这条路线的开始，该项目将研究原位接触型内窥镜SERS的可行性。该项目将从制造用于SERS的纳米金属结构开始。更具体地说，我们将尝试四种不同的方法，以达到表面增强大、均匀性好和制造成本低的目的。这些方法是1)纳米多孔硅的纳米模塑，2)纳米球的纳米模塑，3)纳米球光刻后的掩模形状转移蚀刻，以及4)碳纳米管（CNT）薄膜的室温沉积。SERS底物将在各个方面进行表征，并相互比较。将开发内窥镜SERS探头，它由SERS衬底，渐变折射率透镜，光纤和外壳组成。这些组件将组装和包装后对准。它的特性将通过内部建造的拉曼光谱仪系统进行检查，该系统由激光器、二色镜、透镜、线性CCD阵列和计算机组成。开发的SERS探针将成为下一阶段研究的核心组成部分，从离体SERS成像开始。由于SERS的增强与目标分子与纳米金属表面之间的距离密切相关，因此研究干扰材料对成像的影响，以评估所提出方法的可行性至关重要。为此，将使用Shetty等人的Barrett食管Raman研究作为模型，该研究确定了DNA、糖原、油酸和肌动蛋白作为该疾病的诊断标志物质。粘性流体和/或自组装的单层将被放置在目标分子和SERS探针之间，模拟干扰材料。将研究每种分子的最低可检测浓度水平。不同混合比例的分子混合物也将用SERS探针和主成分分析来检查，以评估该方法的准确性。

DESCRIPTION (provided by applicant): Molecular imaging is an emerging technology that can provide information beyond physical appearance of living tissues by detecting molecular signatures in a noninvasive way. This technology can be highly useful for diagnosis, biopsy or surgical guidance, and optimization of preclinical and clinical tests of medication. Among various molecular imaging technologies, Raman spectroscopy is particularly interesting because it is safe, inexpensive, agent-free, and most importantly, capable of detecting multiple molecules simultaneously. Ordinary Raman spectroscopy, however, has a significant drawback, i.e. low sensitivity. Placing nanometallic structures in close proximity with molecules can augment the Raman signal enormously. Utilization of this surface-enhanced Raman spectroscopy (SERS) has a great potential for the molecular imaging. However, it has been only demonstrated in a setting of an external Raman microscope with nanoparticles injected into small animals. Although these demonstrations show promises of in situ SERS, to implement the method in a clinical setting, it has to be used in conjunction with endoscopy to circumvent the penetration limit of light. As a beginning effort along that line, the project will examine the feasibility of in situ contact-type endoscopic SERS. The project will begin with fabrication of nanometallic structures for SERS. More specifically, four different methods will be attempted, aiming at large surface enhancement, good uniformity, and low fabrication cost. Those methods are 1) nano-molding with nanoporous silicon, 2) nano-molding with nanospheres, 3) mask shape transfer etching after nanosphere lithography, and 4) room-temperature deposition of carbon nanotube (CNT) film. The SERS substrates will be characterized in various aspects, and compared to one another. The endoscopic SERS probe head will be developed, which is comprised of a SERS substrate, a graded- index lens, an optical fiber, and a housing. These components will be assembled and packaged after alignment. Its characteristics will be examined by using a Raman spectrometer system built in-house, which consists of a laser, a dichroic mirror, lenses, a linear CCD array, and a computer. Developed SERS probes will become a core component for the next phase of research, starting from ex vivo SERS imaging. Since the enhancement of SERS shows strong dependence on the distance between the target molecules and the nanometallic surfaces, it is critically important to examine the effect of interfering materials to the imaging, to evaluate the feasibility of the proposed method. For this, Raman study of the Barrett's esophagus by Shetty et al will be used as a model, which identified DNA, glycogen, oleic acid, and actin as diagnostic signature substances for the disease. Viscous fluids and/or self-assembled monolayers will be placed between the target molecules and SERS probes, simulating interfering materials. Minimum detectable concentration level will be studied for each type of molecules. A mixture of molecules with various mixing ratio will be examined also with a SERS probe and the principal component analysis to assess the accuracy of the method.