背景:受挥发性的限制,农药在喷洒过程中和喷洒后过度使用并大量流失,削弱了不同物种之间的生态微平衡。酸响应性农药是一种巧妙的工程农药,有助于以酸控方式提高农药活性成分的利用效率,而酸性溶液的实施可能会扰乱目标植物周围微环境的平衡或造成二次污染,在更精确的策略中强调酸的输入。
结果:用光酸产生剂(2-硝基苯甲醛)作为光操纵酸的自我供应商对壳聚糖进行了化学改性,在此基础上,通过凹凸棒石和有机磷酸盐杀虫剂毒死蜱的集成,配制出一种智能农药。在紫外光(365nm)的照射下,改性的壳聚糖将经历光解反应以产生酸和原始壳聚糖,它抓住了不稳定的质子,并基于其固有的pH响应灵活性促进了毒死rif的释放。根据农药的释放性能,毒死蜱在紫外光(27.2mW/cm2)下的释放率达到78%,显著高于阳光下的(22%,4.2mW/cm2)并在相同时间内处于黑暗中(20%),与紫外线下pH降低至5.3一致,其他两种情况下pH无明显变化,展示一个有吸引力的紫外光控制,酸推动的释放行为。
结论:与直接酸喷雾方法相比,拟议的原位光诱导在施用农药的斑点上产生酸,避免了酸污染非目标的问题,展示了更高的效率和生物相容性,用于控制酸响应性农药和病虫害管理。©2022化学工业学会。
BACKGROUND: Confined by the volatile property, pesticides are overused and lost significantly during and after spraying, weakening the ecological microbalance among different species of lives. Acid-responsive pesticide is a type of smartly engineered pesticides that contribute to the improvement of utilization efficiency of pesticidal active ingredients in acid-controlled manner, whilst the implementation of acidic solutions may disturb the balance of microenvironment surrounding targeted plants or cause secondary pollution, underscoring the input of acid in a more precise strategy.
RESULTS: Chitosan was chemically modified with a photoacid generator (2-nitrobenzaldehyde) serving as a light-maneuvered acid self-supplier, based on which a smart pesticide was formulated by the integration of attapulgite and organophosphate insecticide chlorpyrifos. Under the irradiation of UV light (365 nm), the modified chitosan would undergo a photolytic reaction to generate an acid and pristine chitosan, which seized the labile protons and facilitated the release of chlorpyrifos based on its inherent pH-responsive flexibility. According to the pesticide release performance, the release rate of chlorpyrifos under UV light (27.2 mW/cm2 ) reached 78%, significantly higher than those under sunlight (22%, 4.2 mW/cm2 ) and in the dark (20%) within the same time, consistent with the pH reduction to 5.3 under UV light and no obvious pH change for the two other situations, exhibiting an attractive UV light-controlled, acid-propelled release behavior.
CONCLUSIONS: Compared to direct acid spray approach, the proposed in situ photo-induced generation of acid locally on the spots of applied pesticide circumvents the problem of acid contamination to nontargets, demonstrating higher efficiency and biocompatibility for the controlled delivery of acid-responsive pesticides and pest management. © 2022 Society of Chemical Industry.