On-Demand Activation of Pectin-Gated Chlorine-Doped Cu ₂ O for Synergistic Treatment of Bacterial Infections in Plants

Bacterial fruit blotch (BFB) is a destructive disease threatening global watermelon production. To address this challenge, we developed a bioresponsive and light-enhanced nanopesticide based on pectin-gated chlorine-doped cuprous oxide (Cu2O-Cl@Pectin, CCP NPs) for precision BFB control. Theoretical calculations confirm that Cl doping narrows the band gap of Cu2O and enhances O2 activation, resulting in improved visible-light absorption and increased generation of superoxide anions for effective photocatalytic bactericidal activity. Moreover, the pectin shell serves as an intelligent “gatekeeper”, remaining inert under normal conditions but being specifically degraded by pectinase secreted by the pathogen during infection. This response activates a synergistic antibacterial mechanism, combining photocatalysis with the release of copper ions. Consequently, CCP NPs showed excellent efficacy in suppressing BFB in both leaf infection models and pot-grown watermelon plants, while exhibiting no significant toxicity to nontarget organisms. By integrating on-demand activation with solar energy utilization, this system significantly reduces the reliance on conventional copper inputs and minimizes environmental leakage, thereby aligning with the principles of green chemistry.