PH-Responsive ZIF-8-Based Metal–Organic-Framework Nanoparticles for Termite Control

Abstract

Pesticides are the primary defending strategy against major biological invaders and important for ensuring national food security. Intelligent nanopesticides with precise controlled release modes are currently an emerging area of interest in the field of green, safe, and sustainable pesticide formulation. In this study, β-cypermethrin (β-CYP) was loaded into ZIF-8 by the one-pot method, which successfully prepared a pH-responsive delivery nanoparticle (β-CYP/ZIF-8) to control termites. Results demonstrated that β-CYP/ZIF-8 had a mean diameter of 188 ± 2 nm and a loading capacity of approximately 21%. In vitro release experiments showed that β-CYP/ZIF-8 releases better in acidic than in neutral conditions due to the presence of intermediate acid-unstable imidazole organic compounds. The acidic microenvironment in which termites thrive can promote β-CYP release due to ZIF-8 decomposition, thus improving pesticide targeting and reducing toxic side effects. The bioactivity survey confirmed that β-CYP/ZIF-8 could control termites (Coptotermes formosanus Shiraki) for a longer duration compared to commercial wettable powder (WP) and emulsifiable concentrate (EC). Moreover, an acute toxicity test showed an over 2- and 10-fold reduction in the acute toxicity of β-CYP/ZIF-8 to earthworms and zebrafish, respectively, compared to that of commercial WP and EC. Finally, the cytotoxicity assay of β-CYP/ZIF-8 showed higher safety to human hepatocyte LO2 cells. Overall, these β-CYP/ZIF-8 nanoparticles, prepared using the one-pot method, have great application potential in sustainable pest management and protection of the ecological environment.