表面增强拉曼光谱超高灵敏现场检测食品中黄曲霉素的方法研究

Aflatoxin (AF) is one of the most toxic mycotoxins and most carcinogenic substances. A series of recent outbreaks of human aflatoxicosis and AF contamination in food products have caused a great demand of a new technique for simple, fast, and ultrasensitive on-site detection of aflatoxins. Current techniques such as HPLC fail to meet all these requirements. In this project, surface-enhanced Raman scattering (SERS) combined with nanotechnology and immunolabeling technology is used to construct an "antibody-antigen-antibody" sandwich-like immunocomplex which is composed of superparamagnetic Fe3O4/Au (core/shell) nanoparticle conjugated with AF antibody, AF antigen, and AF antibody labeled with Rhodamine 6G molecules. Using an external magnet, the complex nanoparticles are concentrated and aggregated to a spot, where the detection limit of AF is signifcantly improved due to both the enormous surface enhancment effect at the hot spot and the tremendous enrichment of Rhodamine 6G molecules by magnetic concentration, leading to super-high sensitivity and excellent selectivity of AF detection. This technology eliminates the necessity of sample pretreatment (e.g., purification and concentration) in traditional measurements and thus can find wide application in outdoor testing and fast on-site detection with a portable Raman spectrometer. The research will benefit the investigation of mechanism of SERS "hot spot" effect, facilitate the prevention and control of AF food contamination, and promote the development of detection techniques in food safety.

黄曲霉素（AF）是目前已知毒性最强的真菌毒素也是最强的致癌物之一。近年来AF食品污染与中毒事件频发，迫切需要一种对AF超高灵敏、简单快速、户外现场检测的新技术，传统HPLC等方法难以满足这些要求。本项目将表面增强拉曼光谱（SERS）与免疫技术、纳米技术相结合，用AF抗体修饰的超顺磁Fe3O4/Au(核/壳)纳米颗粒与罗丹明6G标记的AF抗体高选择性地靶向捕获溶液中微量AF，形成抗体-抗原-抗体"夹心三明治"结构的免疫复合物，在外部磁铁作用下将免疫复合物磁性纳米颗粒聚集浓缩成一点，利用该点处巨大的SERS热点增强效应和磁浓缩效应双重降低检测限，达到超高灵敏、高选择性检测AF的目的，从而也免去了传统方法中样品需浓缩、纯化等复杂预处理，通过使用便携式拉曼光谱仪，达到简单快速、户外现场检测的要求。本项目对SERS"热点效应"的机理研究、AF食品污染的预防与控制、食品安全检验技术的发展具有重要意义。

【摘要】黄曲霉素是一种毒性极强的天然致癌物，对人体健康、生活环境以及粮食经济都有极大的危害，黄曲霉素B1（AFB1）已被国际癌症研究机构（IARC）列为人类的第一类致癌剂。传统检测方法如薄层色谱法（TLC）、高效液相色谱法（HPLC）和酶联免疫吸附法（ELISA）等，需要专业人员操作、复杂耗时，并且ELISA可能出现假阳性结果，难以实现现场快速分析。表面增强拉曼光谱（SERS）是一种简便快捷、超高灵敏的检测技术，构建具有优良SERS增强效应的拉曼基底是提高检测灵敏度与检测速度的关键。本文用金纳米颗粒以及金磁纳米颗粒与黄曲霉素抗体（antiAFB1）合成了免疫金拉曼活性基底，并利用SERS技术对AFB1的进行了快速检测。