新荧光探针的构建及农药残留从土壤向植物迁移与传导的原位分析方法研究

The issue of soil pesticide residues exceeding the standards relates to sustainable development of human. The study of pesticide residues migration and transit mechanism from soil to plant can build up a theoretical basis and provide research methods for the remediation of contaminated soils. But lacking feasible methods of analysis is the key technical problem. This project select parathion and chlorfenson on behalf of pesticide residues for in situ analysis of their migration and transit from soil to cabbage. Firstly, design quantum dots immune probe with high sensitivity and good selectivity by coupling pesticides antibody and quantum dots with tunable wavelength and high luminous efficiency. In parallel with the special equipments will be designed for in situ labeling pesticide residues in non-integrated samples of soil and plant. To establish a quantitative relationship between luminescence intensity and pesticide residue content, use laser scanning confocal microscopy to observe distribution and trajectory of pesticide residues in plant rhizospheres and to study the interface processes of rhizospheres, transit and conduction mechanism of pesticide residues in plants. Eventually, competitive migration of multiple pesticide residues in the rhizospheres and the difference pesticide residues in vegetative organs were determined simultaneously with multicolor quantum dots. Establishing situ analysis of the trace organic compounds migration in non-integrated complex samples is the development of analytical chemistry from the study of material composition and structure to the in-depth study of composition, content, spatial and temporal distribution of substance in different state and evolution process, this is a very significant project.

土壤中农残超标问题关系到人类的可持续发展。对土壤中农残向植物迁移、传导机理进行研究，可为污染土壤的修复提供理论基础和研究方法。但上述研究的关键技术问题是缺乏可行的分析方法。本项目选择对硫磷，杀螨酯为农残代表，研究其在土壤-白菜中的迁移和传导的原位分析方法。设计将光谱可调谐的高发光效率的量子点与农药免疫抗体偶联，构建新型的量子点免疫探针；设计专用装置使探针能原位标记土壤-植物非一体样品中的农残；用激光共聚焦显微镜观察根际、植物器官中的农残分布及轨迹，研究农残在根际的界面过程、转化机制及在植物中的传导机理，建立发光强度和农残含量可视化定量关系；用不同波长的探针研究多种农残在根际的竞争迁移，不经分离同时测定植物器官中不同农残。建立非一体复杂样品中微量有机物迁移的原位分析方法，是分析化学从研究物质的组成和结构，向研究物质在不同状态和演变过程中成分、含量和时空分布的发展和深入，是一项有意义的工作。

农药残留对食品及生态的危害已受到各国政府和民众前所未有的关注，建立农残迁移的原位分析及快速可视化检测方法无疑是一项有意义的工作。原位分析方法的核心问题是发光探针，本项目设计构建了具有不同识别功能的五类荧光探针。探针的识别元件分别有抗体、适配体、植物激素及环糊精，探针的发光元件分别是碳点、聚合物点、Mn掺杂ZnS、N掺杂的GQDs、CdSe、CdTe、CdTeMn、C3N4，纳米银。通过偶联等方法将识别元件和发光元件结合制备探针，用多种手段对其进行表征，并将探针应用于农药残留等分析物的原位成像及定量检测中。.取得的主要结果如下：(1) 建立了免疫荧光探针lgG-CDs原位检测白菜幼苗根部中草甘膦残留的方法；lgG-CDs与草甘膦结合后，利用Fe3O4-GLY结合过量的探针lgG-CDs，经磁铁分离后，溶液中lgG-CDs的荧光强度与草甘膦浓度的对数成线性关系，线性方程为F-F0=2099+1022 lgC (C: μg/mL)，线性范围为0.01~80 μg/mL，检出限为8 ng/mL。(2) 建立了免疫荧光探针PDs-Ab直接应用于苹果上亚胺硫磷农残的原位可视化半定量分析；在聚二甲基硅氧烷( PDMS)片表面逐层组装亚胺硫磷及探针，PDMS上探针的荧光强度与亚胺硫磷浓度呈良好的线性关系，线性方程为：F=26.88 C-21.84 (C: ng/L)，检出限为0.36 ng/L。(3)基于碳纳米管能猝灭ZnS:Mn-Aptamer探针的荧光，当啶虫脒存在时荧光重新恢复，由此建立了“turn-on”型传感器对白菜幼苗根部及白菜叶面啶虫脒残留的原位成像分析方法。该成像方法无需洗涤，过量试剂不产生荧光背景干扰。在0-150 nmol/L范围内，F/F0与啶虫脒的浓度呈良好线性关系，线性回归方程为F/F0=1.101+0.03122C (C: nM)，检出限为0.7 nM。.本项目设计的探针其发光元件由传统的含重金属的CdTe量子点等转为无毒的纳米材料如ZnS:Mn、碳点、聚合物点等，探针的识别元件由抗体、适配体等不同识元件构成。构建的探针荧光性能优良，对目标物选择性好。同时通过磁性分离、吸附富集、开关型荧光等策略大大提高了分析方法的灵敏度。