Use of Mg-Al nanoclay as an efficient vehicle for the delivery of the herbicide 2,4-dichlorophenoxyacetic acid

Anionic exchange materials, such as layered double hydroxides (or nanoclays) are established delivery vehicles for bioactives in the pharmaceutical industry. In contrast, the use of these same nanoclays for the delivery of agrochemicals is not well explored yet has great potential for transporting and transferring bioactives to plants that compromise agricultural crop productivity. Herein, we have prepared a MgAl-layered double hydroxide (MgAl-LDH) nanoclay loaded with 2,4-dichlorophenoxyacetic acid (2,4-D) and characterized this material using Fourier-transform infrared, nuclear magnetic resonance, X-ray powder diffraction and Transmission electron microscopy. Spray application of agriculturally relevant doses of bare nanoclay (from 0.2% w/v to 1.0% w/v) on to Arabidopsis thaliana plants did not induce cellular damage or stress when tested for the site-specific stress marker, callose (a β-1,3 glucan). In vitro studies showed that the 2,4-D was slowly released from the preloaded nanoclay over 18 h. When compared to positive controls, spray-applied at equivalent doses, the 2,4-D loaded nanoclay applications (from 0.6 to 1.0% w/v) clearly showed a stronger and irreversible herbicidal effect on the test plants. We therefore propose that nanoclay materials have distinct advantages over conventional surfactant-based agrochemical spray applications and can contribute toward advanced agricultural practices.