pH-responsive copper-doped ZIF-8 MOF nanoparticles for enhancing the delivery and translocation of pesticides in wheat plants

Metal-organic framework (MOF)-based "nanopesticides" with pH-responsive performance have attracted increasing attention for application in sustainable agriculture. However, little attention has been paid to the impact of nanocarriers on the translocation of nanopesticides in plants. Herein, copper-doped ZIF-8 bimetallic MOF nanoparticles (Cu@ZIF-8) were prepared as nanocarriers by in situ fabrication of ZIF-8. Fludioxonil-loaded Cu@ZIF-8 (Flu@Cu@ZIF-8) could be constructed, and the loading content was 23.9%. The average particle size of Flu@Cu@ZIF-8 was & SIM;80 nm. Flu@Cu@ZIF-8 exhibited acid-responsive release, with cumulative release of 79.5%, 69.9%, and 43.0% at pH values of 5, 7, and 9, respectively, after 48 h. Compared with free fludioxonil, Flu@Cu@ZIF-8 had similar percent inhibition against Fusarium graminearum, and the acute toxicity of fludioxonil against zebrafish could be reduced by up to 68% for Flu@Cu@ZIF-8 after 96 h of exposure. Confocal laser scanning microscopy showed that FITC-labeled Cu@ZIF-8 could be transported to all parts of a wheat plant from its roots. Flu@Cu@ZIF-8 exhibited stronger uptake and translocation in wheat plants, with a translocation factor 23-41% higher than that of fludioxonil alone. Overall, this work provides insights into the use of stimuli-responsive metal-doped MOF nanocarriers as pesticide-delivery systems in sustainable agriculture.