Fabrication of a pH-responsive nanodelivery platform based on ZnO and kasugamycin for synergistic delivery in the efficient and green management of rice bacterial leaf streak

The construction of an environmentally responsive bactericidal platform enables intelligent and synergistic regulation of bacterial diseases. A pH-responsive pesticide nano delivery system (ZnO@PDA-KAS) was prepared by self-polymerizing a polydopamine (PDA) coating on the surface of ZnO nanospheres synthesized via a hydrothermal method, followed by conjugation with kasugamycin (KAS) in this work. The results showed that ZnO@PDA-KAS exhibited excellent cumulative release under acidic conditions, with a pesticide loading content of 9.4%. The presence of PDA significantly enhanced the adhesion and retention of nanoparticles on rice leaves, whereas fluorescein isothiocyanate-labeled ZnO@PDA exhibited good translocation capacity in rice plants. Moreover, the PDA coating effectively improved the photostability of KAS. In vivo and in vitro antibacterial tests demonstrated that ZnO@PDA-KAS displayed superior antibacterial activity against Xanthomonas oryzae pv. Oryzicola ( Xoc ) due to the synergistic antibacterial effects of Zn 2+ and KAS. This enhanced activity was attributed to the nanoparticles' ability to severely damage bacterial microstructures, enhance rice enzyme activity, and more effectively inhibition of bacterial biofilm formation and induced more severe DNA damage in Xoc cells. Finally, the ZnO@PDA-KAS nanoparticles showed excellent biocompatibility with rice plants and L02 cells. Therefore, the environmentally responsive bactericide ZnO@PDA-KAS provides effective agricultural guidance for efficient and precise release for the management of bacterial plant diseases.