Construction of Iron-Modified Lignin-Based Nanomicrocapsules for Enhancing the Functionality of Natural Product–Based Pesticides

To address the issue of low pesticide utilization owing to poor dispersibility, low leaf surface adhesion, and poor transport within plants, this study exploits electrostatic interactions between sodium lignosulfonate (SL) and dodecyltrimethylammonium chloride (DTAC) to induce self-assembly, followed by iron ion (Fe³⁺) chelation and loading with a natural product–based pesticide, rosin–based triazole derivative (RTD), yielding RTD@SL–DTAC–Fe nanomicrocapsules (NMs). It is worth noting that the presence of Fe³⁺ enhances the dispersibility of the NMs. The water dispersibility and photostability of RTD are significantly improved after encapsulation, and a stimulus response to laccase is achieved. Leaf-washing experiments confirm the enhanced adhesion of RTD@SL–DTAC–Fe NMs to the surface of rice plant leaves compared to that of free RTD. Fluorescently labeled NMs exhibit bidirectional transport within rice plants, and RTD@SL–DTAC–Fe NMs demonstrates better transport performance than RTD. In vitro and in vivo antifungal tests indicate that encapsulation by NMs significantly enhanced pesticide activity. Field trials demonstrate that NMs exhibited prolonged efficacy compared to RTD. Finally, the safety evaluation confirms the environmental friendliness of the NMs. This study provides valuable insight for optimizing and improving the utilization efficiency and biosafety of natural product–based pesticides.