Synthesis and fungicidal activity of pH-responsive pyraclostrobin/zeolite imidazole ester framework material nanoparticles

Zeolite imidazole framework-8 (ZIF-8) has good stability, large specific surface area, adjustable nanometer particle size and the easy decomposition under acidic conditions. In order to study its performance and application prospects as a slow and controlled release carrier in pesticide delivery, pH-responsive release formulation Pyr@ZIF-8 was prepared by one-pot method using pyraclostrobin (Pyr) as the model pesticide, with divalent zinc as the ligand center and dimethylimidazole as the organic ligand. In addition, the morphology, particle size and Zeta potential were characterized by the scanning electron microscope (SEM), dynamic light scattering laser particle size analyzer (DLS), fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and other physical means to Pyr@ZIF-8. The morphology, particle size and Zeta potential were characterized. And high performance liquid chromatography (HPLC) was used to investigate its photolysis stability under ultraviolet light source and its acid controlled release performance under different pH values. Finally, fungicidal activity in vitro and in pot experiment were studied. The results showed that the average particle size of Pyr@ZIF-8 was 143.1 nm, and the loading rate was 10.8%. The anti-photodegradation experiments showed a 6.2% reduction in the degradation rate of Pyr in Pyr@ZIF-8 nanoparticle under UV light. After standing for 24 h under the environment of pH 4.0, 6.0 and 8.0, the release rate of Pyr in Pyr@ZIF-8 was 88.1% ± 2.5%, 67.3% ± 3.1% and 25.6% ± 2.9%, respectively, suggesting that Pyr@ZIF-8 had pH-responsive release performance. At a concentration of 0.1 μg/mL, the inhibitory effect of Pyr@ZIF-8 on Sclerotinia sclerotiorum was 16.4% (in vitro) and 9.4% (in pot experiment) higher than its EC. The above results showed that the nano-delivery system Pyr@ZIF-8 not only had the effect of slowing down the photo degradation of Pyr, but also had good pH responsive slow-release performance and higher antifungal efficacy.