A pH/cellulase dual stimuli-responsive cellulose-coated metal-organic framework for eco-friendly fungicide delivery

Smart pesticides that respond to environmental stimuli can achieve the on-demand release of pesticides to control pests and diseases, thereby reducing the amount of pesticides used, and reducing the risk to the envi-ronment. In this study, a pH/cellulase dual stimuli-responsive controlled-release pesticide formulation (PYR@-UiO-66@HPC) was successfully fabricated by encapsulating pyraclostrobin (PYR) and coating hydroxypropyl cellulose (HPC) within a metal-organic framework (MOF, i.e., UiO-66). The obtained results demonstrated that PYR@UiO-66@HPC exhibited an excellent PYR release behavior in response to acidic and cellulase environments similar to the environment at the time of Rhizoctonia solani infestation. In addition, PYR@UiO-66@HPC exhibited a higher fungicidal activity than commercial microencapsulated formulations, and biosafety tests showed that PYR@UiO-66@HPC had less effect on non-target organisms, especially on Daphnia magna, with a toxicity of 4.6 times lower than that of PYR-TC after 48 h. Furthermore, it did not affect the normal growth of the target rice crop and had a low impact on the soil microbial community. Finally, cytotoxicity assays showed that PYR@UiO-66@HPC had little effect on cell proliferation and apoptosis in LO2 cells compared with the free PYR, thereby indicating a superior biocompatibility and an improved human safety profile. This study therefore provides a smart, eco-friendly, and sustainable strategy for the effective control of plant diseases.