基于分子在纳米间隙动态吸附行为的表面增强拉曼光谱的痕量检测方法

表面增强拉曼光谱（SERS）在物理、化学、生物和材料等领域已获得广泛应用，然而，痕量物种的高灵敏检测仍是SERS面临的一个重大挑战，主要原因在于：待测分子与SERS基底相互作用的强弱和SERS光谱中背景的变化都对SERS信号产生显著影响。针对该问题，本项目拟建立毫秒级时间分辨SERS光谱和成像检测平台，以银纳米粒子为增强源，构建结构明确不同类型的SERS基底，以与基底作用强弱不同的分子动态吸附行为为研究对象，开展以下工作：1）分离SERS信号和背景，通过暗场光学和扫描电镜成像共定位技术将光谱信息与微区结构关联，探讨背景来源，考察拉曼信号和背景的动态相关性。2）改变介质环境因素，调控金属和分子间相互作用，研究分子动态吸附及其对SERS增强效应的影响。总之，项目基于结构明确的SERS纳米结构，从研究分子动态吸附和建立合理的SERS增强效应评估方法的角度为提高SERS痕量检测灵敏度提供借鉴和帮助

Surface-enhanced Raman spectroscopy (SERS) has a wide application in the fields of physics, chemistry, biology and materials, due to the high sensitivity at the single molecular level and the finger-printed spectrum. However, the quantitative detection of the trace amount of species is still a great challenge in this field. The main reason lies: both the interaction between adsorbed molecules and SERS substrates and the fluctuation of the background in SERS spectra play significant role. With these quiz in mind, we build a SERS detection & imaging platform with the millisecond time resolution and the single molecular detection level. Taking Ag Nanoparticles as enhancement source to construct different type of SERS substrates, and the dynamic adsorption of molecules with varied interaction with silver nanoparticles as the model, the following works will be carried out: 1）Separating SERS signal and background efficiently via millisecond resolved SERS spectra; Correlating SERS spectra with the nanostructure of SERS substrate via the correlation of dark field optical images and SEM ones; Discovering the origin of the background in SERS spectrum, and analyzing the dynamic relationship between SERS signal and background; 2) Investigating molecular adsorption dynamics and its contribution to SERS enhancement by manipulating the interaction between SERS substrates and molecules with varied environmental conditions, such as the introduction of anions or electrode potentials. Therefore, On the basis of the above study on the SERS substrate with well-defined nanostructure, from the angle of investigating the dynamic adsorption and building a more reliable protocol to evaluate the SERS enhancement, we try to provide new sight and idea for improving the sensitivity toward trace amount detection.