engleski

Impact of silver nanoparticles on physiological parameters of tobacco seedlings

Silver nanoparticles (AgNPs) are among the most commonly applied nanomaterials due to their powerful antibacterial and antimicrobial properties that are being exploited in a number of consumer products. As a consequence, AgNPs are expected to enter natural ecosystems where they can undergo biodegradation or bio-accumulate in the food chain and act as a potential environmental hazard. Plants, as primary producers, are very likely to be influenced. Bioaccumulation of AgNPs is dependent on the characteristics of the particles, with mainly their size and surface coating determining their mobility and transport in the environment. In this study, we compared the effects of two differently coated AgNPs [polyvinylpyrrolidone (AgNP-PVP) and cetyltrimethylammonium bromide (AgNP-CTAB)], applied in three concentrations (25, 50 and 100 μM), on photosynthesis and oxidative stress parameters of tobacco (Nicotiana tabacum) seedlings. Silver uptake in the plant tissue was determined with inductively coupled plasma mass spectrometry (ICP-MS). Chlorophyll fluorescence parameters were measured by fluorimeter using a saturation pulse method. Dihydroethidium test was used to determine the content of reactive oxygen species (ROS). Ascorbate peroxidase (APX), pyrogallol peroxidase (PPX), superoxide dismutase (SOD) and catalase (CAT) activities were spectrophotometrically measured. Although both types of AgNPs significantly increased the silver content in the plant tissue, the highest amount of Ag was detected in 100 μM AgNP-CTAB treatment. Both AgNPs induced ROS formation that was again much more pronounced with AgNP-CTAB. Changes in antioxidant enzymes activities were also observed. AgNP-PVP significantly decreased PPX and APX activity in all tested concentrations, but no changes were detected in CAT and SOD activity. AgNP-CTAB decreased PPX and SOD activity, and increased CAT activity at the highest concentration. Both AgNP-PVP and AgNP-CTAB lowered most of the chlorophyll fluorescence parameters, indicating a negative influence on the photosynthetic apparatus. Even though both types of AgNPs caused phytotoxic effects on tobacco seedlings, these results indicate that the degree of damage correlates with the surface coating used for AgNPs stabilization.

silver nanoparticles ; Nicotiana tabacum ; reactive oxygen species ; fluorescence ; antioxidant enzymes

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