engleski

Cysteine can alleviate silver nanoparticle-induced toxicity in tobacco seedlings

Silver nanoparticles (AgNPs) are a commonly used nanomaterial because of their antibacterial and antifungal properties that are exploited in numerous consumer products and agriculture. Increased AgNPs utilisation results in their significant discharge into the environment and many studies have already revealed their toxic effects on living organisms. Plants, with an important role in bioaccumulation and distribution of environmentally released substances, could serve as a potential route for AgNPs into the food chain. To analyse how different coatings affect AgNP phytotoxicity the effects of 25, 50 and 100 µM polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB) -coated AgNPs on tobacco seedlings (Nicotiana tabacum L.) oxidative stress response were compared. To examine if AgNP-toxicity is nanoparticle-specific or it derives from dissolved Ag + , 125, 250 and 500 µM cysteine, a strong silver-complexing ligand, has been applied. Ag content was measured using ICP-MS. A dihydroethidium test was used to determine the ROS level. For oxidative damage evaluation, malondialdehyde (MDA) and protein carbonyls content and the activities of antioxidant enzymes (pyrogallol peroxidase (PPX), ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD)) were spectrophotometrically determined. The results showed increased Ag uptake and elevated ROS levels in both AgNP-treatments compared to the control, although no significant difference in MDA and protein carbonyls content was detected. AgNP-PVP decreased APX and PPX activities, while AgNP-CTAB increased CAT and decreased PPX activity. Cysteine in combination with AgNPs significantly reduced ROS formation, probably due to alleviated activities of antioxidant enzymes. These results show that AgNPs phytotoxicity partially derives from dissolved silver.

antioxidant enzymes ; ICP-MS ; lipid peroxidation ; nanosilver, protein carbonyls ; reactive oxygen species

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