CAREER: Plasmonic Nanocavities for Single Molecule Detection

等离子体纳米腔用于单分子检测本提案描述了一项综合的研究、教育和推广计划，重点是等离子体纳米腔及其在单分子表面增强拉曼光谱(SERS)中的应用。所提出的等离子体纳米腔，或金属纳米线(Ag)之间的微小间隙，是通过在垂直取向的第一层银纳米线的顶部堆叠第二层平行的银纳米线而形成的。初步研究表明，当顶部和底部纳米线之间的间隙减少到几纳米或人类头发直径的十万分之一时，照明光可以聚焦到这样微小的纳米隙中，光强度增加高达100000倍。当分子被放置在这些等离子体纳米腔中时，它们的拉曼散射强度可以大大增强，因此甚至可以观察到单分子信号。拉曼光谱代表了分子独特的振动信息，可用于分子的直接检测和鉴定。这项拟议的研究旨在开发纳米线和纳米腔的纳米制造工艺，表征和基本了解这些等离子体纳米腔，并探索它们在表面增强拉曼散射中的应用。最终目标是展示一个基于SERS的健壮的单分子传感平台。该教育计划包括实施一项教育计划，旨在吸引俄亥俄州东北部的高能力学生进入STEM(科学、技术、工程和数学)专业，并为已经在STEM领域的学生提供指导和研究机会。智力优势：银纳米线交叉棒在三个方面具有独特性：(1)纳米天线(即银纳米线)和纳米腔集成在单一平台上，使将光聚焦到纳米级变得高效；(2)垂直腔体设计使使用薄膜沉积技术以前所未有的精度制造纳米GaP成为可能；(3)这些纳米空间中的分子可以通过通过这些纳米线施加电压来进行电寻址，从而提供了极大的灵活性来控制分子和纳米空间。这项研究将回答关于SERS增强机制的基本问题，并导致可重复性的单分子传感器的发展。更广泛的影响：拟议的研究有益于社会，因为单分子传感器可以找到从国土安全到医疗保健疾病诊断的无数应用。这一职业计划的教育和外展部分包括为肯特州立大学(KSU)的高等教育入学选择计划(PSEOP)的学生开发一个指导研究体验计划；指导本科生的研究；创建一个名为？家长？S之夜？的外展计划？面向高中生及其家长；通过让研究生参与多学科研究来加强研究生教育，并开发研究生水平的纳米/生物材料教学课程。KSU是俄亥俄州三所最大的公立大学之一，超过80%的KSU学生是本科生；KSU主要服务于中低收入本科生。这种不同寻常的机构特征组合使KSU非常适合从代表性不足的群体和/或弱势社区招收学生，从事科学和相关领域的职业。拟议的教育计划将对提高科罗拉多州立大学科学和相关领域中代表性不足的群体成员和妇女的入学率、保留率和毕业率产生直接影响。

Plasmonic Nanocavities for Single Molecule DetectionThis proposal describes an integrated research, education and outreach plan with a focus on plasmonic nanocavities and their applications in single molecule surface enhanced Raman spectroscopy (SERS). The proposed plasmonic nanocavities, or the tiny gaps between metal nanowires (Ag), are formed by stacking a second layer of parallel Ag nanowires on top of a first layer of perpendicularly oriented Ag nanowires. Preliminary studies show that when the gaps between top and bottom nanowires are reduced to a few nanometers or ten millionth of the diameter of a human hair, illuminating light can be focused into such tiny nanogaps with up to 100000 times increase in light intensity. When molecules are placed inside these plasmonic nanocavities, their Raman scattering intensity can be largely enhanced so that even single molecule signals can be observed. The Raman spectra represent unique vibration information of molecules which can be used for direct detection and identification of the molecules. The proposed research aims at developing nanofabrication processes for nanowires and nanocavities, characterization and fundamental understanding of these plasmonic nanocavities, and exploring their applications in SERS. The ultimate goal is to demonstrate a robust single molecule sensing platform based on SERS. The education plan includes implementing an educational program aimed to attract high ability students in Northeast Ohio to majors in STEM (science, technology, engineering and mathematics) fields and to provide those students already in STEM fields with mentoring and research opportunities.Intellectual merit: The Ag nanowire crossbars are unique in three aspects: (1) nanoantennas (i.e. Ag nanowire) and nanocavities are integrated in single platform, making it highly efficient to focus light into nanometer scale; (2) the vertical cavity design makes it possible to fabricate nanogaps with unprecedented accuracy by using thin film deposition techniques; (3) Molecules within these nanocavities can be addressed electrically by applying voltages through these nanowires, providing great flexibility to control the molecules and nanocavities. The proposed research will answer fundamental questions about SERS enhancement mechanisms and lead to development of reproducible single molecule sensors. Broader impact: The proposed research benefits society because single molecule sensors can find myriad applications from homeland security to disease diagnostics for healthcare. The educational and outreach components of this career plan include developing of a guided research experience program for the Post Secondary Enrollment Option Program (PSEOP) students at Kent State University (KSU); mentoring undergraduates in research; creating an outreach program called ?Parent?s Night? for high school students and their parents; enhancing graduate education through involving graduate students in multidisciplinary research, and developing curriculum for teaching nano/biomaterials at the graduate level. KSU is one of three largest public universities in the state of Ohio, over 80% KSU students are undergraduates; and KSU primarily serves low- to middle-income undergraduates. This unusual combination of institutional traits makes KSU ideally suited to recruit students from under-represented groups and/or disadvantaged communities to pursue careers in science and related fields. The proposed educational plan will have a direct impact on improving enrollment, retention, and graduation rates of under-represented group members and women in science and related fields at KSU.