Agrochemicals are used to increase crop productivity and reduce the impact of plagues on crops. Important issues such as poor targeting, leaching and degradation promotes multiple agrochemical applications at high concentrations to achieve desired effects. Nano delivery systems have the potential to improve the effectiveness of agrochemicals and reduce their negative environmental impact by improving the delivery of the active ingredients. In this study we explore translocation of methoxyfenozide (MFZ) delivered by lignin nanoparticles (LNPs) in soybean plants exposed to the particles through the roots under hydroponic conditions. LNPs (106 ± 5 nm in diameter, with a polydispersity index of 0.121 ± 0.011 and a zeta potential of -42 ± 4.6 mV) were synthesized by emulsion evaporation from lignin-graft-poly(lactic-<i>co</i>-glycolic) acid. Translocation of MFZ, a non-systemic pesticide, was measured in plants exposed for 24 h to the LNPs loaded with MFZ at 2.7% w/w. Soybeans were grown hydroponically and were treated with 0.02, 0.2 or 2 mg/ml of LNPs at 28 days after germination. Plants were harvested after 6, 12, and 24 hours of continuous particle exposure to the roots. Root, stem, and leaves were collected and concentration of MFZ was quantified by HPLC. Results suggested effective translocation of MFZ from the hydroponic solution to the roots, and from the roots to the leaves when exposed for longer periods of time. MFZ concentrations at 24h in the plants treated with 2mg/ml NPs were 519.30, 3.72 and 1.72 µg/g in the roots, stem, and leaves, respectively, compared to the concentrations achieved with the free MFZ of 28.52, 0.58, 0.39 µg/g in the roots, stem, and leaves, respectively. MFZ concentrations showed an increase with the time of exposure. MFZ concentration in the leaves at 6, 12 and 24 h of were 0.05, 0.06 and 0.08 µg/g at low concentration; 0.15, 0.48, and 0.96 µg/g at medium concentration; and 0.22, 0.44, and 1.72 µg/g at the high concentration. The concentration of MFZ within the plant was mostly accumulated in the roots. Nevertheless, at the lowest concentration of LNPs tested, the MFZ in the leaves and stems was highest relative to the roots, measuring 5.47, 7.83, and 5.7% at 6, 12 and 24 h respectively compared to 3.83, 2.77, and 6.6% at medium concentration, and 0.97, 0.23, and 0.53% at high concentrations. LNPs were able to translocate MFZ from the hydroponic solution to the roots, and to the stems and leaves, albeit in small amounts over 24 h.

Translocation of methoxyfenozide delivered by lignin nanoparticles in soybean plants

ACS Fall 2021

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