Despite the wide range of possible applications of nanopesticides, the mechanisms involved in their enhanced action remain largely unknown. Understanding the interaction between nanopesticides and plants is crucial for evaluating their potential safety application. Using an experimental and theoretical approach, this study aimed to investigate the target effect of paraquat-loaded chitosan/tripolyphosphate nanoparticles (ca. 200 nm) on photosystem I (PSI). Electrochemical analysis showed distinct electroactivity behaviour between the encapsulated and non-encapsulated herbicide. The amount of lipid peroxidation, photooxidizable P700 reaction centre content, and NADPH/NADP⁺ ratio levels were significantly decreased in spinach leaf tissue exposed to the nanoherbicide compared to those with the non-encapsulated herbicide. The data also revealed that the nanoformulation might promote oxidative stress based on changes observed in antioxidant enzymes. Also, molecular docking results showed a preferential disposition of the herbicide paraquat and paraquat–tripolyphosphate complex (TPP:PQ) in the ligand domain close to FAD and Glu312. Due to the inhibitor's strategic position in the catalytic pocket, a model of electron-capture is proposed, where the herbicide disturbs the redox process NADP⁺ ⇌ NADPH by capturing electrons to reduce itself. Finally, our findings provide important insights where the redox behaviour of paraquat may play a key role in the enhanced efficiency of nanoherbicides to the target binding site.

中文翻译：

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携带百草枯的壳聚糖/三聚磷酸盐纳米制剂：增强除草活性的见解

尽管纳米杀虫剂的可能应用范围很广，但其增强作用所涉及的机理仍是未知之数。了解纳米农药与植物之间的相互作用对于评估其潜在的安全应用至关重要。使用实验和理论方法，本研究旨在研究百草枯负载的壳聚糖/三聚磷酸盐纳米颗粒（约200 nm）对光系统I（PSI）的目标作用。电化学分析表明，在包封的和未包封的除草剂之间有明显的电活性。脂质过氧化的量，可光氧化的P700反应中心含量和NADPH / NADP ⁺与未包封的除草剂相比，暴露于纳米除草剂的菠菜叶片组织中的比率水平显着降低。数据还显示，基于抗氧化剂酶的变化，纳米制剂可能会促进氧化应激。此外，分子对接结果表明，在接近FAD和Glu312的配体域中，优先处理了除草剂百草枯和百草枯-三聚磷酸盐复合物（TPP：PQ）。由于抑制剂在催化口袋中的战略位置，提出了一种电子捕获模型，其中除草剂干扰了氧化还原过程NADP ⁺AD NADPH通过捕获电子来还原自身。最后，我们的发现提供了重要的见解，其中百草枯的氧化还原行为可能在纳米除草剂对目标结合位点的效率提高中起关键作用。