Integrated nanotechnology for synergism and degradation of fungicide SOPP using micro/nanoAg(3)PO(4)

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.