Reducing liquid surface tension is widely employed to enhance droplet retention on broad, rigid crop leaves such as cabbage and cucumber; however, its effectiveness on young hydrophobic weeds with lightweight, flexible foliage remains poorly understood. On such leaves, droplet impact readily induces leaf motion, which intensifies fragmentation and splashing, thereby reducing deposition and increasing leaching risks. Here, we report a supramolecular nano-formulation in which the herbicide 2,4-D and the biobased surfactant rhamnolipid (RHL) co-assemble into uniform nanoparticles (mean diameter 134.33 nm) via hydrogen bonding and van der Waals interactions. Compared with two commercial salt formulations, this design reduces liquid surface tension by more than 55.5%, enabling efficient spreading and interfacial wetting on hydrophobic polytetrafluoroethylene (PTFE) surfaces. On three small hydrophobic weed species, droplets from commercial formulations detached rapidly upon impact, whereas nanoparticle-laden droplets adhered strongly and moved synchronously with the leaves. Beyond enhanced retention, the nano-formulation exhibits temperature-responsive release, suppresses herbicide leaching, and achieves superior control of both broadleaf and grass weeds in pot trials, while markedly reducing toxicity to zebrafish, earthworms, and human cells. Together, these findings establish a supramolecular co-assembly strategy that integrates high herbicidal efficacy with improved environmental safety, offering a promising platform for sustainable weed management.
Xiao et al. (2026) studied this question.