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

描述（由申请人提供）：分子成像是一种新兴技术，可以通过以非侵入性方式检测分子特征来提供超出活组织物理外观的信息。该技术对于诊断、活检或手术指导以及药物的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，拉曼光谱特别令人感兴趣，因为它安全、便宜、无试剂，最重要的是，能够同时检测多个分子。然而，普通的拉曼光谱具有显著的缺点，即低灵敏度。将纳米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）技术进行分子成像具有很大的潜力。然而，它仅在外部拉曼显微镜的设置中被证明，纳米颗粒被注射到小动物中。虽然这些演示显示了原位Sers的前景，但为了在临床环境中实施该方法，必须与内窥镜结合使用，以规避光的穿透限制。作为沿着这条线的开始努力，该项目将研究原位接触式内窥镜Sers的可行性。该项目将开始与Sers纳米结构的制造。更具体地说，将尝试四种不同的方法，旨在大的表面增强，良好的均匀性，和低制造成本。这些方法是1）用纳米多孔硅纳米模塑，2）用纳米球纳米模塑，3）在纳米球光刻之后的掩模形状转移蚀刻，以及4）碳纳米管（CNT）膜的室温沉积。Sers基底将在各个方面进行表征，并彼此进行比较。研制了一种内窥镜Sers探头，它由Sers基片、梯度折射率透镜、光纤和外壳组成。这些组件将在对齐后进行组装和包装。它的特性将通过使用内部构建的拉曼光谱仪系统进行检查，该光谱仪系统由激光器、分色镜、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件，从离体Sers成像开始。由于Sers的增强表现出强烈的依赖于目标分子和纳米表面之间的距离，这是至关重要的，以检查干扰材料的成像的效果，以评估所提出的方法的可行性。为此，Shetty等人对Barrett食管的拉曼研究将被用作模型，其鉴定了DNA、糖原、油酸和肌动蛋白作为该疾病的诊断特征物质。粘性流体和/或自组装单层将被放置在目标分子和Sers探针之间，模拟干扰材料。将研究每种类型分子的最低可检测浓度水平。还将使用Sers探针和主成分分析来检查具有不同混合比的分子的混合物，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.