基于苯并咪唑的苯甲酰基脲类似物的超分子自组装及杀菌性能研究

On account of the big size of particles and poor dispersion, the loss of pesticides are up to 70-90%, which not only increased the cost of pesticides, but also did harm to the ecological environment. There have been reported that if the particles of pesticides decreased from traditional micro-to nano- scale, the coverage and adhesiveness of pesticides on the leaves of plants and surface of pests would be fortified obviously because of its smaller size and larger specific surface effect, thereby reducing the amount and frequency of pesticide application and increasing the utilization ratio of pesticides. Most of the research on the nano-pesticides are focused on the microencapsulation products, but the degradation of the macromolecular wall material is slow and therefore, increase burden on environment. If the nano-pesticides are exploited by self-assembly based on low molecular compounds, the procedure will be simplified, and the cost will be decrease a lot. Targeted at chitin in fungi cell wall, benzimidazole is introduced into the benzoylureas through active substructure combination. Aggregates with nano-scale and diverse morphologies will be expected to be formed by self-assembly through hydrogen bonds and π-π stacking force. Morphology will be recorded by TEM, SEM and AFM, while the properties will be undertaken through rheology, DLS and CD. The stacking model will be derived by IR and XRD. Fungicidal activities in vivo and in vitro will be investigated, and the effects of the particle size and morphology on the fungicidal activities will be discussed, in order to improve the activities and the effective utilization of pesticides, to provide experimental basis and theoretical basis for the development of nano-pescicides in China.

由于农药粒子较大、分散性差，在田间有效成分流失达70-90%，不仅增加了用药成本，还对生态环境造成危害。若将粒子降至纳米级，则由于小尺寸、大比表面效应，会增加在作物叶面及有害生物表面的覆盖率、黏附性，提高有效利用率。对纳米农药的研究多关注于微囊产品，但许多高分子微囊壁材降解慢，增加了环境负担，若以小分子化合物为基元进行超分子自组装，开发纳米农药，则可简化开发步骤、降低研发成本。本课题拟以真菌细胞壁为靶标，设计合成含苯并咪唑的苯甲酰脲类化合物，并在氢键、π-π堆积作用力下进行自组装，期望得到具有纳米尺度、不同形貌的组装体。通过TEM、SEM、AFM对其形貌进行研究，通过流变、DLS、CD等对其性能进行测试，并由IR、XRD推测堆积模型；对组装体及溶液的杀菌活性进行测试，探讨粒子尺度、组装体形貌对活性的影响，以达到提高药物活性、有效利用率的目的，为我国纳米农药的发展提供实验基础和理论依据。

由于农药粒子较大、分散性差，在田间有效成分流失达70～90%，不仅增加了用药成本，还对生态环境造成危害。本课题提出以小分子化合物为基元进行超分子自组装，通过减小农药粒子尺度，则由于小尺寸、大比表面积、更好的膜穿透性等原因，对药效的提升起到积极作用。本项目共设计合成了三个系列，共49个含杂环的脲类化合物，并对其结构通过IR、1H NMR、EA进行了表征。针对常见植物病原菌，以95%百菌清为对照药剂，采用生长速率法，对目标化合物的离体抑菌活性进行了初步测试。结果表明：在50 mg L-1的测试浓度下，部分化合物显示较好的抑菌活性，高于对照药剂95%百菌清。对代表性化合物的自组装性能进行研究，选取代表性化合物，采用不同的溶剂体系，如水、水-DMSO、THF，通过加热、超声等方法进行自组装，并通过SEM或TEM确认其组装形貌。结果表明，所选取的化合物可在多种溶剂中实现自组装，呈现规整的纳米粒子、纤维、棒状或片层形貌。部分化合物可在水-DMSO（VH2O:VDMSO=99:1）中进行自组装，此体系可安全用于植物病原菌的抑制。此外，部分化合物可在水中实现自组装，避免了有机溶剂的使用，符合农药剂型水基化发展的要求。对传统配样方式配制的药液和发生自组装后形成不同形貌组装体的生物活性差异进行了研究。以菌核菌、赤霉菌为研究对象，通过传统配样及自组装配样两种方式分别配制药液，对其抑菌活性进行研究。结果表明，50 mg L-1下，自组装后的药液比传统配样的药液表现出更好的抑菌活性。如化合物Ⅱc未进行组装配样时对菌核菌的抑制率为71.67%，而发生自组装后药液的抑制率为80.00%，药效提高了11.62%，组装后的药效与对照药剂啶酰菌胺相当（80.00%）。Ⅱc未组装配样时对赤霉菌的抑制率为6.70%，而发生自组装后药液的抑制率为11.70%，药效提高了74.63%。这说明农药粒子尺度的减小有利于药效的提高，有利于降低农药使用量、提高农药利用率，符合国家对农药减量控害的要求。以上研究结果为我国纳米农药的发展提供实验基础和理论依据。

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