Metal–Phenol Network Engineering Enables Solid State Encapsulation of Uniconazole as a Deep Delivery System

Abstract

The concept of efficient and low-cost nanopesticide production drives the development of sustainable green preparation strategies. Herein, a novel uniconazole@tannic acid-Fe (UZ@TA-Fe) micro/nanocapsule delivery system is constructed via mechanochemical technology utilizing uniconazole as a model pesticide. Under the action of mechanical force, the TA-Fe complex formed by tannic acid (TA) and Fe³⁺ is uniformly coated on the surface of the uniconazole particles. The effects of grinding tank materials (agate and zirconia) and dry and wet grinding on the morphology and particle size of the capsules are systematically studied. Due to the different energies carried by different density media, there are differences in the shape and size of micro/nano capsules prepared by dry grinding using agate (AD) and zirconia (ZD) grinding media. The optimized UZ@TA-Fe(ZD) nanocapsules demonstrate high loading content (89.3%) and small size characteristics (467.1 nm). Field trials showed that UZ@TA-Fe(ZD) nanocapsules were superior to commercial wettable powder products in promoting bud formation and increasing cotton yield. The uptake and transport of UZ@TA-Fe(ZD) nanocapsules in cotton roots are demonstrated by confocal laser scanning microscopy and transmission electron microscopy. The nanocapsules entering the root tip and main root cells indicate that uniconazole can be deeply delivered. This strategy provides a new idea for green large-scale preparation of pesticide micro/nanocapsules.