环境敏感型高岭土基农药智能释药体系构建及控释机理

Based on the good adsorption capacity of modified kaolinite and the particular characteristics of natural polymers for preparation of environment sensitive hydrogels, a mixed system of kaolinite and polymer is to be constructed as encapsulation material for the controlled release of pesticides. Spinosad and chlorantraniliprole are to be used as the model pesticides due to their good performances of high efficiency, low toxicity and broad spectrum. According to the alkaline pH level of intestinal juice in lepidoptera and the temperature range for fast growth or serious damage of these pests, the temperature- and pH- sensitive kaolinite-based formulations will be prepared by reacting with the corresponding pH- and temperature- sensitive polymers. The constructed kaolinite-based intelligent system has the function of making the active constituent of pesticide respond to the environment temperature and intestinal pH, and thus can improve the targeting and environmental compatibility of the pesticide formulations. Laboratory bioassay and simulated field trial of the pesticide controlled release system against lepidoptera such as Spodoptera exigua larvae, Mythimna separata (Walker) and Helicoverpa armigera (Hübner) will be carried out, and the results will be compared with those of traditional formulations. The specific mechanism between encapsulation materials and model pesticides will be further explored by means of computational chemistry and instrumental analysis. The results will provide a theoretical reference for the control mode of precision pesticide application.

根据鳞翅目有害昆虫中肠液偏碱性的特点及其发育或危害高峰的温度范围，本申请拟基于改性高岭土优良的吸附性能以及天然高分子易于制备环境敏感型水凝胶的特性，以两者混合体系为包封材料，以多杀菌素、氯虫苯甲酰胺等高效、低毒、广谱杀虫剂为模式药物，通过引入pH和温度敏感因子，制备高岭土基温度/pH（碱性）敏感型农药智能化控释剂型，使农药活性物质可响应环境温度和昆虫肠液pH，提高农药剂型的靶向性和环境相容性。以甜菜夜蛾幼虫、粘虫和棉铃虫等典型鳞翅目害虫为研究对象，以传统剂型为对比，通过室内生物测定和模拟田间药效试验评价载药智能控释剂型的性能。在此基础上，以计算化学和现代仪器分析方法为主要手段，确定包封材料与模式药物之间的作用机理，探讨载药智能控释体系随温度和pH变化的释药机理，为实现精准施药的农药防治模式提供一定的理论支撑。

农药缓/控释制剂近年来一直是化学农药新剂型的一个重要研究方向。温度和pH是昆虫生理中两个重要的因素，具备响应有害昆虫中肠液pH或其危害温度的智能化剂型对实现农药的靶向性和环境相容性至关重要。本项目制备了同时响应pH和温度的多杀菌素控释颗粒制剂，制备了多种同时响应pH和温度的多杀菌素和氯虫苯甲酰胺控释微球悬浮液；系统研究了其在不同pH和温度下的体外释药行为，阐明了其在不同pH和温度下的释药规律，初步探究了其释药机理。. 研究结果表明，多杀菌素控释颗粒制剂外观淡黄色，形态好，粒径均匀（0.6～1.2 mm），包封率近100%，载药量15～40%。在20～55℃之间，颗粒制剂的溶胀度均随着pH的升高呈现先升高后降低的趋势，在pH=7.4时溶胀度最高，但释药速率在pH≥7.4后基本保持不变，表现出明显的pH敏感性。在pH 为1.2～10.0之间，控释颗粒的溶胀度均随着温度的升高（20～55℃）逐渐增大，释药速率亦逐渐加快，表现出明显的温度敏感性。多杀菌素和氯虫苯甲酰胺控释微球中粒径D50均在40 μm左右，80%以上粒子粒径分布在5~100 μm之间，包封率大于90%，载药量15～35%，与控释颗粒相似，其释药特性亦表现出类似地pH和温度敏感性。本研究制备的颗粒制剂和微球悬浮液均能响应鳞翅目有害昆虫中肠液pH，有望提高多杀菌素和氯虫苯甲酰胺等疏水性农药的靶向性和环境相容性，具有一定的应用前景。