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Coated silver nanoparticles affect germination and disrupt tobacco growth

Silver nanoparticles (AgNPs) are being used in an ever increasing number of consumer products due to their excellent antibacterial and antifungal properties. Increased production will inevitably increase the potential for their release into the environment. Plants, as key components of biological systems, may serve as a potential pathway for AgNPs uptake, bioaccumulation and a route into the food chain. In this study we compared the effects of three differently coated AgNPs [citrate, polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB)], applied in three concentrations (25, 50 and 100 μM), on germination and early growth of tobacco (Nicotiana tabacum L.). AgNPs-citrate did not cause any significant changes in germination percentage, but the germination rate of plants treated with AgNPs-PVP and AgNPs-CTAB was significantly reduced. Root elongation and seedling growth were also negatively affected, resulting in reduction of fresh and dry mass and a decreased stress tolerance index. To examine whether the toxic effects of AgNPs-PVP and AgNPs-CTAB originate from dissolved Ag+ or nanoparticles themselves, 125, 250 and 500 μM of cysteine, a strong silver ligand, have been applied. Cysteine significantly reduced the harmful effects of AgNPs, thus showing that phytotoxicity of AgNPs at least partially derives from dissolved silver.

silver nanoparticles ; cysteine ; Nicotiana tabacum ; germination ; stress tolerance index

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