Integrated nanotechnology for synergism and degradation of fungicide SOPP using micro/nano-Ag3PO4

Abstract

The pursuit of food safety and environmental protection has encouraged the development of new antifungal agents to replace traditional fungicides. Here we present an integrated green nanotechnology using inorganic materials, Ag₃PO₄ micro/nano-crystals, which could enhance the efficiency of fungicide sodium o-phenyl phenolate (SOPP) but without its residue remaining. The experiments demonstrate that the micro/nano Ag₃PO₄ was effective in inhibiting fungal hyphae growth against Phytophthora capsici and Botrytis cinerea. After being combined with Ag₃PO₄ micro/nanocrystals, the antifungal activities of fungicides SOPP and cyproconazole were enhanced. More importantly, it was found that over 90% of the SOPP was decomposed by the Ag₃PO₄ at a dose of 1.6 g L⁻¹ under simulated sunlight irradiation within 2 h, exhibiting a much better photocatalytic activity than ZnO nanoparticles (NPs). These achievements demonstrate that this green nanotechnology could reduce fungicide usage without compromising on pathogen control and provide a residue-free effect under natural environmental conditions. Furthermore, it was found that the antifungal activity of Ag₃PO₄ was not due to the production of ROS but strongly related to interaction with fungal cells and the release of Ag⁺ ions. The mechanism for the synergistic enhanced antifungal effect was speculated from three possible aspects: (a) Ag₃PO₄ micro/nano-crystals and Ag⁺ ions promoting the penetration of OPP ions into the cell interior; (b) formation of a Ag₃PO₄–SOPP composite; and (c) multiple modes of antifungal action of the Ag₃PO₄–SOPP system.