壳-核“热点”修饰三维SERS-FET柔性基底制备及其在生物分子检测中的应用

The SERS technique can realize real-time and fast detection, which has been widely used in the field of the environmental monitoring ,food safety and medical diagnosis and treatment. The commonly used planar rigid SERS substrate not only can't achieve in situ detection, but also own many inevitable disadvantage such as strong background fluorescence, molecular signal of easy to deform and too unitary information. In this project, firstly, the optimal structure is explored by means of simulation software, Comsol and Vasp. And on this basis, the core-shell structure with two-dimensional as the shell material and metal nanostructures as a nuclear based SERS substrate with high-density "hot spots" and good reproducibility can be obtained in three-dimensional flexible substrates in virtue of in-situ preparation technology. Moreover, its combination with FET can realize the light - electrical double signal output of biological molecules, which is finally applied to in situ detection of foodborne pathogenic bacteria salmonella. By analysing the interaction mechanism between SERS, standing wave light and potential regulating and characteristics of molecular adsorption, dispersion and aggregation, the project will improve the sensitivity of SERS - FET sensors. This study has an important guiding significance for deep understanding of SERS mechanism and designing the high-sensitivity sensors, has important application value for prevention and treatment of foodborne diseases.

SERS技术具有灵敏度高、速度快、可实时检测等特点而被广泛应用于环境监测、食品安全及疾病诊断等众多领域。通常采用的硬性平面SERS基底不能原位检测，且存在背景荧光强、信号易变形、信息单一等缺点。本项目首先利用Comsol和Vasp软件设计模型，寻求最优化结构，在此基础上，利用原位制备技术在三维立体式柔性基底上制备由二维材料（壳）和金属纳米结构（核） 组成的 “壳核”结构，得到“热点”密度高、可重复性好的SERS柔性基底，并通过与FET联用，实现生物分子的光-电双信号输出，最终将该技术应用于食源性致病菌沙门氏菌的原位检测。项目通过研究分析SERS、光驻波、电位调节相互作用机理和分子吸附、分散及聚集特点，探索SERS、FET以及二者联用的增强机制，提高SERS-FET传感器的灵敏度。研究对深入理解SERS机理，设计高灵敏度传感器具有重要的指导意义，对食源性疾病的预防和诊疗具有重要的应用价值。

金属纳米结构硬性SERS基底不能原位检测，且存在背景荧光强、分子信号易变形、信息单一、较难检测混合生物分子等缺点。本课题在已有的研究基础上将二维纳米材料直接生长在金属纳米结构的表面，制备得到多类型二维材料壳-金属纳米结构核高“热点”密度结构，提高了对检测分子的吸附能力并减弱背景荧光，获得了均匀、可重复、高灵敏、稳定的拉曼信号；进一步将得到的核壳结构制备为柔性SERS基底，实现了对分析物的原位检测；基于核壳结构构建了场效应管（FET）双传感模式的生物传感器，在磷酸盐缓冲液和人血清中实现了低至0.62aM和0.91aM浓度微囊藻毒素的检测的有效检测；将核壳结构结合自发电系统，研究SERS信号、电位调节相互作用机制，有效增强了检测分子的拉曼信号，并实现了对胺基苯酚分子氧化为4-硝基苯硫酚分子的原位监测。在理论和实验上证明了电位对等离激元局域热载流子密度的可控调节，为调控SERS检测、改善原位催化监测提供了一种新思路，对其他光学传感技术同样具有重要的参考价值。