Eco-corona reduces the phytotoxic effects of polystyrene nanoplastics in Allium cepa: Emphasizing the role of ROS

Abstract

Nanoplastics are widespread in the environment, and their increased persistence is an indisputable and severe threat. The impacts of these nanoplastic particles on the soil system and terrestrial plant growth, as well as how the EPS secreted by soil microbes would influence their toxic effects remain largely unexplored. This study focuses on the toxic effects of polystyrene nanoplastics (PSNPs) of various surface charges (plain, aminated, and carboxylated) and concentrations (12.5, 25, and 50 mg/l) in Allium cepa and illustrates the effects of eco-corona formation in reducing the toxic impact. The endpoints evaluated included cytotoxicity, oxidative stress (total ROS, superoxide, hydroxyl radical generation and lipid peroxidation), and antioxidant enzyme activity (catalase and guaiacol peroxidase). Among the various surface charges, aminated PSNPs showed the highest toxicity for all the three concentrations tested. The results showed a concentration reliant increase in the levels of cell death, oxidative stress generation, and antioxidant enzyme activity for pristine PSNPs irrespective of their surface charges. Upon aging in the EPS medium a decrease in the toxic effects was noted for all the indicators. This could be a result of the agglomeration due to eco corona formation over the PSNPs in the EPS medium. The TEM images and MHD analysis for both pristine and the coronated PSNPs confirmed the agglomeration. • Cell physiology of onion roots treated with Polystyrene nanoplastics studied. • Eco-corona formation by soil EPS over the polystyrene nanoplastics. • Coronated Polystyrene nanoplastics tend to agglomerate reducing their cell uptake. • Reduced oxidative stress and toxic effects by coronated Polystyrene nanoplastics.