PDA-CeO2 Functionalized Pickering Microcapsules with Enhanced Foliar Retention and UV Stability for Efficient Pesticide Delivery

Abstract Pesticide spraying applications often encounter challenges such as inadequate foliar deposition, low retention, and rapid photodegradation, which can significantly impact pesticide utilization. Microencapsulation of pesticides offers a viable solution to these issues. In this study, we encapsulated pyraclostrobin (PYR) within polydopamine-CeO2 modified polyurea microcapsules (PYR@PDA-CeO2–PU MCs) using Pickering emulsion interfacial polymerization. The PDA-modified CeO2 nanoparticles (PDA-CeO2 NPs) acted as the primary emulsifier and ultraviolet (UV) absorber, providing enhanced adhesion, controlled release, and UV protection. The PYR@PDA-CeO2–PU MCs demonstrated an encapsulation efficiency of 82.22 ± 2.00% and a loading capacity of 41.00 ± 1.50%, with a release profile consistent with the Higuchi model. The incorporation of PDA significantly improved leaf retention and adhesion, while the covalent attachment of PDA-CeO2 to the PU shell enhanced the photostability of PYR. After 72 h of UV irradiation, PYR@PDA-CeO2–PU MCs achieved a retention rate of 82.55 ± 0.80%, compared to 74.82 ± 0.44% for Seltima and 53.11 ± 0.91% for PYR TC. In vivo tests on rice and kiwifruit leaves demonstrated superior protective and curative effects, while toxicity assessments indicated reduced toxicity to zebrafish compared to PYR TC. In conclusion, the PDA-CeO2 functionalized PU MCs exhibit remarkable foliar retention and UV stability, thereby enhancing the practical application of pesticides.