Gelatin/chitosan/MIL-101(Fe) hybrid-stabilized Pickering emulsion with dual pH/redox responsiveness for sustained pendimethalin release and improved foliar adhesion.

Abstract

Sustainable and stimuli-responsive delivery systems provide a promising strategy to improve agrochemical utilization efficiency while mitigating the environmental risks of conventional pesticide formulations. Herein, we report a volatile organic solvent-free Pickering emulsion stabilized by gelatin, chitosan, and MIL-101(Fe) nanoparticles, which achieves dual pH- and redox-responsive co-delivery of the herbicide pendimethalin and antibacterial thyme essential oil. The pH-triggered swelling of the biopolymer matrix and the redox-induced degradation of the MIL-101(Fe) framework jointly contribute to on-demand release of active ingredients. Meanwhile, the composite stabilizer system significantly enhances foliar deposition, as reflected by a 30.8% decrease in contact angle and an 88.9% increase in liquid holding capacity compared with a commercial emulsifiable concentrate (EC). The Pickering emulsion shows herbicidal activity equivalent to that of the commercial formulation, together with favorable antibacterial performance and no obvious phytotoxicity to maize. Collectively, this work constructs a sustainable, multifunctional, and stimuli-responsive agrochemical delivery platform with enhanced deposition efficiency and biosafety, providing a universal strategy for the design of next-generation green pesticide formulations.