Ameliorating effect of surfactants against silver nanoparticle toxicity in crop Fagopyrum esculentum L.

Abstract

Surfactants are known to play a critical role in influencing the nanotoxicity in various biological systems. However mechanism of surfactants influence the nanoparticle-induced toxicity in higher plants is still unknown. In this study we investigated the potential role of three different surfactants; hexadecyl trimethylammonium bromide (CTAB), triton X-100 (TX-100) sodium dodecyl sulphate (SDS) in mitigation of AgNPs-induced toxicity in plant Fagopyrun esculentum.A sub-lethal dose of AgNP (500 mg Kg-1 soil) was selected based on the phytotoxicity test. Similarly predetermined non-toxic doses of surfactants; CTAB, 0.01 mg Kg-1; Triton TX-100 1.0 mg Kg-1 and SDS 0.01 mg Kg-1 soil were supplemented with sub-lethal dose AgNP to assess the role of surfactants towards AgNP induced phytotoxicity. Morphological changes, oxidative stress parameters, cellular and genotoxic assay, antioxidant enzymes assays were performed and correlated with the level of intracellular Ag metal.Results showed that plants exposed to AgNP exhibited dose dependent inhibition in morphological parameters. AgNP also induced oxidative stress in plant in terms of increase in the cell death (77.4%), H2O2 production (92.3%), level of MDA (61.8%) and carbonyl content (69.5%), which corroborated with oxidative damage to DNA by AgNP (138.5%). However, surfactant remarkably reduced AgNP induced oxidative stress and substantially improve the activities of key antioxidative enzymes. Thus it was deduced that surfactants exhibits ameliorating effects against AgNP induced oxidative damage by strengthening the antioxidative system in F. esculentum. Importantly, use of surfactants significantly decreased the intracellular Ag content in plant perhaps due to increase in the particle size of AgNPs. Among surfactants higher ameliorating effect was shown by TX-100, followed by CTAB and SDS. Overall findings clearly demonstrated that AgNP induced toxicity in F. esculentum was substantially alleviated by the surfactants, which not only improve the plant tolerance against AgNP, but also reduced the excess Ag accumulation by plants.