基于可调控量子点标记适配子的中药材上真菌毒素多元高通量分析体系构建

Traditional Chinese Medicine (TCM), as an excellent treasure of Chinese culture, made great contributions to the health of Chinese people and prosperity of China. The quality of TCM determines their safety and efficacy. The quality control of TCM becomes a great issue in the modernization of TCM. Surveys of mycotoxins in TCMs indicated that different levels of mycotoxins occurred in China. For example,among total 57 traditional Chinese medicinal plants samples collected from different places, the results showed that 23 among 31 visibly moldy samples and 2 among 26 not visibly moldy samples were contaminated with ochratoxin A (OTA), at levels ranging from 1.2 to 158.7 and 2.5 to 5.6 μg kg-1, respectively. Obviously, mycotoxin contamination in TCMs could be a serious health risk to human. .Various analytical methods for the determination of mycotoxins in TCMs, including thin-layer chromatography (TLC), enzyme-linked immunosorbent assay systems (ELISA), gas chromatography (GC) combined with electron-capture detection (ECD) or mass spectrometry (MS), high-performance liquid chromatography (HPLC) with fluorescence detection (FD) or diode array detector (DAD) or MS, have been reported. However, it is easier to produce pseudo-results using ELISA methods to detect mycotoxins. Also, the use of LC-MS/MS method is restricted to expensive apparatus. With the development of technology and the safety requirements of TCMs, it is necessary to develop a simple and reliable method for the determination of mycotoxins in TCMs, to monitor mycotoxins levels in TCMs and evaluate its potential hazard to human..Nucleic acid aptamers, selected from a synthesized library of random single-stranded oligonucleotides, are oligonucleotide ligands binding to target molecules with high specificity and affinity. Nucleic acid aptamers have similar functions to antibodies, but possess the advantages of wider range of targets, better stability, easier modification and synthesis. The quantum dots have the unique physical and chemical properties, such as size-dependent tunable photoluminescence, broad excitation spectra, narrow emission bandwidths and good photostability..In this project, the aptamers of mycotoxins will be screened from the large random nucleic acids libraries by SELEX (Systematic Evolution of Ligands by Exponential Enrichment) technique. The controlled CdTe quantum dots will be synthesized in aqueous medium in order to obtain CdTe/CdS core/shell type quantum dots. Then, the controlled CdTe quantum dots will be used to label the obtained aptamers of mycotoxins in order to establish the analysis system of the high throughput screening of mycotoxins in TCMs. This project is very important for quality control of TCMs. The construction of this original analysis system with the simple, fast, reliable and high sensitivity would be very valuable for mycotoxins analysis in TCMs.

本课题拟在我们前期研究的基础上，重点针对黄曲霉毒素、赭曲霉毒素等毒性大、易污染中药材的真菌毒素，基于组合化学和PCR扩增的体外筛选技术，采用分子生物学、光学、化学和分析学等多学科的技术手段和分析方法，筛选出能以极高的亲和力和特异性与真菌毒素靶分子结合的适配子。基于量子点具有激发光谱范围宽、发射光谱窄且峰形好、发射光谱可调、量子产率高等优异的光学特性，采用水相法制备高性能CdTe/CdS核壳型可控量子点，将可调控的量子点标记筛选得到的真菌毒素适配子。通过可控量子点的多色标记构建中药中真菌毒素的多元高通量分析体系。采用SPSS数理统计软件，对比多元高通量新体系和UPLC-MS/MS检测结果，确证所构建新体系在中药材上的适用性和准确性。该课题的实施对中药在生产、流通过程中防止真菌毒素的污染，保证中药质量，突破国外的贸易壁垒，消除中药中真菌毒素的潜在安全隐患，具有重要的理论和实际应用双重意义。

本课题重点针对黄曲霉毒素、赭曲霉毒素等毒性大、易污染中药材的真菌毒素，采用光学、化学和分析学等多学科的技术手段和分析方法，构建中药中真菌毒素的多元高通量分析体系。通过四年的系统和深入研究，（1）合成了CdSe/CdS量子点，该量子点具有6~10层的无机CdS单分子层，随着壳层的增加，可以有效的保护核心CdSe量子点免受中药复杂基质的荧光淬灭作用。（2）合成了以CdSe为核的CdSe/6CdS核壳型和CdSe/CdZnS合金型两种量子点作为荧光免疫分析方法中发光性能优越的荧光标记物。（3）研究了油溶性量子点的转相方法和与蛋白偶联的方法，获得基于量子点标记的荧光探针。（4）建立了基于量子点标记及甘氨酸信号增强的间接竞争荧光免疫分析法快速测定中药材中AFB1的检测方法。（5）建立了基于量子点标记及甘氨酸信号增强的直接竞争荧光免疫分析法。（6）构建了基于非标记荧光染料PicoGreen结合适配子生物传感器检测黄曲霉毒素B1（AFB1）的新方法。（7）构建了赭曲霉毒素A特异性适体亲和柱（AAC），并考察中药材所含成分对AAC柱效的影响以及AAC柱净化后对降低基质效应的影响。（8）基于分子信标（MB）-适体（Aptamer）二元体系，构建了检测赭曲霉毒素A（OTA）的新方法。（9）建立了适用于多种不同药材基质的基于免疫亲和柱净化测定中药材中黄曲霉毒素的HPLC-FLD方法以及一步提取或简单高效的QuEChERS前处理UPLC-MS/MS真菌毒素多残留测定方法。通过该项目的实施，共发表文章40篇，其中SCI文章33篇（影响因子大于7的两篇），中文文章7篇。培养博士、硕士研究生6名。申报专利2项。提出“LC-FLD 法检测中药中黄曲霉毒素”的ISO（国际标准化组织）标准，参与欧盟Horizon 2020（H2020-SFS-2015-2）项目。上述研究成果为实现中药样品中真菌毒素现场高通量的快速筛查和确证奠定了良好的基础，对中药生产、流通过程中防止真菌毒素的污染，保证中药质量，突破国外的贸易壁垒，消除中药中真菌毒素的潜在安全隐患，具有重要的理论和实际应用双重意义。