Three-dimensional dendritic biosynthetic copper oxide nanoparticles: A novel approach for enhanced leaf deposition and retention to reduce environmental impact.

Bio-CuNPs with three-dimensional network topology were successfully prepared to improve rain-wash resistance and synergistic antimicrobial activity. [Display omitted] • CuO nanoparticles was successfully synthesized using waste tea seed cake extract. • The prepared Bio-CuNPs showeda three-dimensional network topology. • Bio-CuNPs exhibited excellent wettability and resistance to rain-washing. • CuO nanoparticles and tea saponin showed synergistic antimicrobial activity. • Bio-CuNPs displayed good biosafety to plants, microorganisms and aquatic organisms. Copper-based fungicides are commonly utilized as protective germicides; however, their susceptibility to rain-induced washing leads to a substantial copper exposure, resulting in significant environmental pollution and potential ecological risks. This study focuses on the biosynthesis of copper oxide nanoparticles at room temperature, utilizing copper sulfate pentahydrate and tea seed cake extract as reactive raw materials. The obtained copper oxide nanoparticles exhibit a distinctive dendritic three-dimensional topology. Notably, these copper oxide nanoparticles demonstrate superior wettability and spreadability on tomato, rice, and wheat leaves compared to the commercial formulation of copper hydroxide (Kocide). The retention amount of copper oxide nanoparticles on the surface of plant leaves after rain washing exhibited a 75.89% to 84.31% increase compared to that of Kocide, attributed to the structural chimerism of copper oxide nanoparticles and the micro-nano structure of leaves. Regarding antimicrobial activity against Magnaporthe oryzae and Clavibacter michiganense , copper oxide nanoparticles showed better residual activity and a longer persistent period than Kocide. Safety experiments demonstrated that copper oxide nanoparticles had minimal adverse effects on wheat plants, while in vivo studies in zebrafish revealed their effectiveness in reducing toxicity by over five-fold compared to Kocide. Furthermore, soil ecosystem assessments highlighted the high biocompatibility of copper oxide nanoparticles with Escherichia coli. Consequently, the prepared copper oxide nanoparticles hold significant promise as an eco-friendly alternative to traditional copper-based fungicides. [ABSTRACT FROM AUTHOR]