Development of a xanthan gum-based triple-responsive nanogel for intelligent controlled release and performance evaluation of thiamethoxam

Conventional pesticide formulations suffer from low utilization efficiency and off-target effects due to their inability to respond to pest-specific microenvironments. Here, we developed a triple-responsive nanogel carrier via dynamic boronate ester crosslinking between xanthan gum (XG) and a phenylboronic acid (PBA) derivative for targeted delivery of thiamethoxam (TMX). The TMX-loaded nanogel exhibited a drug loading content of 8.7 ± 0.4% and an encapsulation efficiency of 72.0 ± 2.1%, along with uniform particle size (188.7 nm) and good colloidal stability (10 days at 25 °C). It showed rapid drug release under acidic pH, elevated reactive oxygen species (ROS), and high glucose conditions, which mimic the microenvironment at aphid feeding sites. The formulation significantly improved leaf wettability, reducing the contact angle on cabbage leaves from 91.7° to 74.8°, and enhanced rainfastness. Bioassays demonstrated that TMX@DPX-NG achieved a corrected mortality of 62.8% (calculated using Abbott's formula) against Myzus persicae at 24 h, outperforming the technical suspension (43.2%), while exhibiting no phytotoxicity. This nanogel platform, constructed from industrial crop-derived xanthan gum, offers a green and sustainable strategy for precision pesticide delivery within the industrial crop value chain, combining intelligent responsive release with excellent foliar retention.