Insufficient deposition of pesticide droplets and rain erosion are significant factors in excessive pesticide wastage and pose a significant threat to public health and the ecological environment. Inspired by the adhesion mechanism of marine mussels and mayfly larvae, we developed a gel coating to improve pesticide retention efficiency and resistance to rainwater washout by sequential spraying polydopamine-functionalized alginate and Fe3+ ions onto the target leaf surface (SA-DA/Fe3+). Abundant catechol groups provide strong molecular-level interfacial bridging for alginate derivates, while the gel coating contains flexible, deformable, and complex nanoscale networks, inducing mutual coupling with micro/nanostructures on the leaf surface, ultimately resulting in the removal of the interface void and the improvement of deposition capacity at multiple scales. The gel coating shows high cohesive energy to better resist rain rinsing due to the dense carboxyl-Fe3+ and catechol-Fe3+ coordination bonds in the network architecture. By combining the above effects, the pesticide retention rate of SA-DA/Fe3+ gel coating on foliage could reach about 97 % after rain erosion and immersion. In addition, the SA-DA/Fe3+ gel coating can also achieve the sensitive photo-control effect of pesticides due to the intrinsic photosensitivity of the iron-carboxylate system. Using an alginate-based gel coating as a promising strategy for improving pesticide utilization, addressing the issues of easy runoff, susceptibility to erosion, and uneven coverage in traditional pesticide droplet form, thus bridging the fields of bionic materials science, bio-macromolecular chemistry, and agricultural science.

中文翻译：

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通过动态金属配体组装形成的多重生物启发的藻酸盐基凝胶涂层，用于增强农药的叶亲和力和耐雨性


农药雾滴沉积不足和雨水侵蚀是造成农药过度浪费的重要因素，对公众健康和生态环境构成重大威胁。受海洋贻贝和蜉蝣幼虫粘附机制的启发，我们开发了一种凝胶涂层，通过将聚多巴胺功能化的海藻酸盐和 Fe3+ 离子顺序喷洒到目标叶片表面 (SA-DA/Fe3+) 来提高农药保留效率和抗雨水冲刷能力。丰富的儿茶酚基团为海藻酸盐衍生物提供了强大的分子水平界面桥联，而凝胶涂层包含柔性、可变形和复杂的纳米级网络，诱导与叶表面微/纳米结构的相互耦合，最终导致界面空隙的去除和多尺度沉积能力的提高。由于网络结构中存在致密的羧基-Fe3+和儿茶酚-Fe3+配位键，凝胶涂层表现出高内聚能，可以更好地抵抗雨水冲洗。综合上述效果，SA-DA/Fe3+凝胶涂层在经过雨水冲刷和浸泡后，叶片上的农药保留率可达到97%左右。此外，由于铁-羧酸盐体系固有的光敏性，SA-DA/Fe3+凝胶涂层还可以实现农药的灵敏光控效果。利用海藻酸盐凝胶涂层作为提高农药利用率的一种有前景的策略，解决传统农药液滴形式易径流、易侵蚀和覆盖不均匀的问题，从而在仿生材料科学、生物高分子化学、和农业科学。