Multidimensional Stimuli-Responsive and Degradable Pesticide Nanocapsules through On Site Coordination Assembly for Enhanced Pest and Pathogen Control

Abstract

Complete pesticide nanocapsules were readily prepared through an “on site” Fe III -tannic acid (TA) coordination assembly based on oil/water microemulsions stabilized with different types of surfactants and with various pesticides dissolved in the oil phase after only one deposition cycle of Fe 3+ and TA. This is a universal strategy suitable for the oil/water microemulsions stabilized with different types of surfactants and independent of the addition sequence of Fe 3+ and TA. Surprisingly, the smart pesticide nanocapsules showed multidimensional on-demand controlled pesticide release (including acidic pH, alkaline pH, glutathione, ascorbic acid, H 2 O 2, phosphate, phytic acid, and sunlight) as well as excellent resistance to rainwater erosion and ultraviolet photolysis. The examples of ascorbic acid- and phytic acid-triggered controlled release of loaded cargos (including pesticides or drugs) were reported for the first time, respectively. It is the first time that the 8 types of stimuli were integrated into one smart nanovehicle for the on-demand controlled release of encapsulated cargos (including pesticides and drugs). The multidimensional stimuli were closely relevant to the physiological and natural environments of crop plants, and the Fe III -TA wall materials were ultimately degraded in the crop plants. The nanocapsules loaded with the fungicide tebuconazole showed high fungicidal efficacy against fungi Rhizoctonia solani and Fusarium graminearum, and the nanocapsules loaded with the insecticide avermectin have high insecticidal efficacy against the pests Plutella xylostella, in comparison with conventional pesticide formulations. The facile, safe, controlled-release, and degradable pesticide nanocapsules show great application prospects in sustainable ecological agriculture.

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