A sustainable and smart fungicide release platform through cocrystal nanocapsules for improved utilization rate and environmental safety

Pesticides have always been restricted by environmental factors and utilization rate. Smart delivery systems are important to modify pesticides and improve utilization rate, but the economic and environmental risks of the carriers limit their practical applications. Here, responsive release nanocapsules were constructed with metal-phenolic networks and pyraclostrobin - thiophanate-methyl (PYR-TM) cocrystal core to modify the poor physicochemical properties and safety of pesticides. PYR-TM was prepared by sustainable mechanochemical method and deposited by metal-phenolic networks in water, producing the PYR-TM@TA-Cu nanocapsules. The crystal structure and DFT calculations proved that TM improved the photostability of PYR by 75.7-fold through competitive energy absorption of photon and molecular conformation modulation. With a loading capacity up to 91.2%, PYR-TM@TA-Cu exhibited pH-responsive release behavior triggered by acidic conditions, which showed that 43.6%, 51.4%, 62.4% and 81.6% of encapsulated PYR were released at pH 7.9, 6.2, 5.3, and 4.0, respectively. Additionally, PYR-TM@TA-Cu exhibited favorable fungicidal activity (EC50 = 0.123 mg/L) in controlling Botrytis cinerea. The greenhouse control efficiency of fungal infection was enhanced from12.0% to 70.7% by PYR-TM@TA-Cu after 7 days spraying. The coating of metal-phenolic network improved the washing persistence of the pesticides from 51.26% to 79.88%, the security for zebrafish by 42-fold, and decreased the leaching potential of the pesticides. Meanwhile, PYR-TM@TA-Cu showed no phytotoxicity on the growth of corn and cucumber plants. Overall, this study provides insight into efficient and sustainable agricultural production with the construction of an eco-friendly nanocapsules platform by cocrystal engineering strategy.