基于金属颗粒表面等离激元操控的动态拉曼增强检测方法研究

Surface enhanced Raman Scattering (SERS) is a label-free technique for molecular "fingerprint" information acquisition, metallic particle as a basic SERS structure has small invasion to liquid environment such as biological tissue, its using in the enhanced Raman detection has become a research hot spot in biomedical field. Since the enhancements occur at the surfaces of metallic particles, only places where the metallic particles locate can be detected, in order to perform controllably dynamic measurements, the manipulation of metallic particles is highly desirable. For the issue that it is difficult to stably trap metallic particles with traditional optical tweezers, this project plans to generate dynamic SERS structures based on plasmonic manipulation of multiple metallic particles and preform the enhanced Raman detection, which can break through the bottlenecks of small effective detection area, low detection speed and unstable signal etc. in the dynamic detection with manipulating single metallic particle. The research contents of this project include: the study of generation of multiple focuses in plasmonic field with high efficiency; the study of plasmonic manipulation of metallic particles multimer; the study of characterization and enhancement mechanism in multiple metallic particles and metallic film SERS structure; the experimental study of the dynamic enhanced Raman detection and its application in the measurement of cell membrane. The researching of this project and the corresponding achievements are of great significance for enriching the research of label-free and real-time in situ detection and developing the applications for super-resolution Raman imaging of biological cells.

表面增强拉曼散射（SERS）技术是一种无标记的分子“指纹”信息获取手段，金属颗粒作为最基本的SERS结构，对液体环境比如生物组织入侵小，采用金属颗粒进行拉曼增强检测已成为生物医学领域的研究热点。然而增强只局限在金属颗粒表面附近，只能对其所到之处进行探测，要实现可控的动态测量，必须对金属颗粒进行操控。本项目针对传统光镊技术难以稳定捕获金属颗粒的问题，拟采用表面等离激元光镊技术操控多个金属颗粒产生动态SERS结构进行拉曼增强检测，以突破单个金属颗粒操控用于动态检测有效探测区域较小、检测速度低和信号不稳定等瓶颈。本项目的主要研究内容包括：多焦点表面等离子体场高效率产生研究、金属颗粒多聚体表面等离激元操控研究、多个金属颗粒金属膜SERS结构表征及增强机理研究、动态拉曼增强检测实验研究及应用于细胞膜测量。本项目研究及其成果对于丰富无标记实时原位检测研究内涵，推动细胞超分辨拉曼成像的应用具有重要意义。

超表面是一种二维平面的人工材料，它可以通过设计亚波长的微结构来调控光波的振幅、相位和偏振特性。本项目的研究方向是基于超表面能够对光波灵活调控的特性，通过巧妙地设计其结构单元和排列方式，以解决传统光学器件或现有超表面存在的一些问题和不足，及实现诸多新颖的功能。项目内容包括:光场调控、光学操控、拉曼增强、光学传感四部分。项目结果包括：光场调控部分，利用超表面对光波特性的调控，实现了消像差、分束、圆偏振转换功能，以及产生了偏振不敏感的光学涡旋，艾里光束，光学针等新型光束；光学操控部分，利用超表面产生具有相位梯度和强度梯度的聚焦场，实现了对微纳颗粒的捕获，移动，旋转等操作。拉曼增强部分，设计的纳米环二聚体阵列和虚拟-真实探针二聚体两种结构，均实现了高的光场强度增强。光学传感部分，设计的纳米环阵列和法布里-珀罗谐振腔组成的偏振不敏感的折射率传感器，具有高的灵敏度和综合表现性能。本项目的研究丰富了超表面的功能，在成像、光束整形、微粒操控、检测单分子、传感等光学领域中有着重要的应用。此外，超表面具备的亚波长尺寸特性，可集成于上述系统中，使光学系统小型化，利于光学芯片、穿戴设备的发展。