Effects of engineered lignin-graft-PLGA and zein-based nanoparticles on soybean health

Abstract

The majority of published research on the effect of engineered nanoparticles on terrestrial plant species is focused on inorganic nanoparticles, with the effects of organic polymeric nanoparticles (NP) on plants remaining largely unexplored. It is critical to understand the impact of polymeric NPs on plants if these particles are to be used as agrochemical delivery systems. This study investigates the effect of biodegradable polymeric lignin-based nanoparticles (LNPs) and zein nanoparticles (ZNP) on soybean plant health. The LNPs (114 ± 3.4 nm, −53.8 ± 6.9 mV) were synthesized by emulsion evaporation from lignin-graft-poly(lactic-co-glycolic) acid, and ZNPs (142 ± 3.9 nm and + 64.5 ± 4.7 mV) were synthesized by nanoprecipitation. Soybeans were grown hydroponically and treated with 0.02, 0.2, and 2 mg/ml of LNPs or ZNPs at 28 days after germination. Plants were harvested after 1, 3, 7 and 14 days of particle exposure and analyzed for root and stem length, chlorophyll concentration, dry biomass of roots and stem, nutrient uptake and plant ROS. Root and stem length, chlorophyll and stem biomass did not differ significantly between treatments and controls for LNPs-treated plants at all concentrations, and at low doses of ZNPs. At 2 mg/ml ZNPs, the highest concentration tested, after 7 days of treatment chlorophyll levels and root biomass increased and stem length was reduced in comparison to the control. Nutrient uptake was largely unaffected at 0.02 and 0.2 mg/ml NPs. A concentration-dependent increase in the oxidative stresss was detected, especially in the ZNP treated plants. Overall, LNPs and ZNPs had a minimum impact on soybean health especially at low and medium doses. To our knowledge this is the first study to show the effect of zein and lignin based polymeric NPs designed for agrochemical delivery on soybean plant health.