用于微囊藻毒素检测的双金属协同增强拉曼散射微流控系统研究

This proposal is to fabricate a novel bimetallic synergistic surface enhanced Raman scattering (SERS) substrate with isolated layer by using Micro/Nano manufacture method. To understand the mechanism of bimetallic synergistic Raman enhancement, the simulation software is utilized to investigate the relationship between the bimetallic Nano-structure and enhancement of electromagnetic field so as to reveal the effect of SERS Nano-structure, thickness of metal Nano film and the materials of isolated layer on the Raman signal excitation and collection with high efficiency. Furthermore, the effect of fabrication process conditions on the SERS performance are studied to establish the method system for producing the SERS substrate with high sensitivity, uniformity, reproducibility. In the meantime, the design of micro-fluidic channels is optimized using the finite volume method. With the combination of SERS substrate, a micro-fluidic bimetallic synergistic based SERS analytical system for detection of microcystins is developed to investigate the effect of SERS excitation with high efficiency, collection of Raman signal, Micro/Nano optical related light coupling interface on the performance of system. And then, the SERS characteristic spectrum of microcystins is investigated, and the multivariate regression analysis method is used to determine the trace amount of microcystins and reveal the contribution of chemical enhancement and electromagnetic enhancement. The results of this proposal could be able to provide a method to design novel micro-fluidic based SERS system to quantify the concentrations of other many kinds of trace amount of analyte in practical applications.

本项目拟采用微纳加工技术制备带有隔离层的新型双金属协同增强SERS芯片。通过理论仿真，研究双金属纳米结构与电磁场增强之间的关系，弄清SERS芯片结构、金属纳米薄膜厚度、隔离覆盖层材料等对高效激发探测分子拉曼信号的影响规律，阐明双金属协同增强机理。进一步研究制备工艺条件对芯片性能的影响，从而建立活性强、均匀性好、重复性高的SERS芯片制备方法体系。同时，采用有限体积法进行数值计算，优化微流道结构设计，并将SERS芯片有机融入，构建适用于痕量微囊藻毒素检测的SERS微流控系统，阐明芯片的高效激发、光谱信号采集、微纳光学通用光耦联界面等对系统性能的影响。结合理论建模与实验，利用支持向量回归分析方法，识别痕量微囊藻毒素SERS特征光谱，并揭示电磁增强与化学增强的作用与贡献。本项目的实施可为设计和制造高效、高灵敏的SERS芯片及其微流控系统提供理论依据与技术支撑，推动其在各种分析检测领域中的应用。

完成了项目相关的理论和实验研究包括：利用时域有限差分法 (FDTD, Finite Difference Time Domain) 理论模拟仿真获得了SERS基底的电磁场分布，优化了SERS纳米结构的参数。根据待测体系的需求设计了不同类型的SERS基底，主要包括：结合模板复制和镀膜的方法制备了PDMS柔性SERS基底；采用等离子体增强化学气相层积法（PE-CVD）与磁控溅射镀膜方法制备了石墨烯碳墙复合银纳米结构的SERS基底；利用化学合成的方法成功制备了Au Film-Au@Ag Core-Shell NPs基底、Gap-Tethered Au@AgAu基底以及Fe3O4@Au@Ag SERS基底。分别对上述基底进行了理化参数的表征，研究了其SERS增强机制及性能。其中Gap-Tethered Au@AgAu基底实现了对微囊藻毒素（MC-LR）含量检测，检测限可达9.82pM。同时，搭建了微流控拉曼光谱探测系统，结合电控系统以及各个功能模块实现了水体样本的在线监测。获得的相关研究成果包括：发表论文10篇，申请发明专利2 项，其中获得授权1项，受邀在国内外学术会议上作特邀报告5次。