Silver Nanoparticle Effects on Antioxidant Response in Tobacco Are Modulated by Surface Coating

Abstract

The antimicrobial properties of silver and enhanced reactivity when applied in a nanoparticle form (AgNPs) led to their growing utilization in industry and various consumer products, which raises concerns about their environmental impact. Since AgNPs are prone to transformation, surface coatings are added to enhance their stability. AgNP phytotoxicity has been mainly attributed to the excess generation of reactive oxygen species (ROS), leading to the induction of oxidative stress. Herein, in vitro-grown tobacco (Nicotiana tabacum) plants were exposed to AgNPs stabilized with either polyvinylpyrrolidone (PVP) or cetyltrimethylammonium bromide (CTAB) as well as to ionic silver (AgNO3), applied in the same concentrations, either alone or in combination with cysteine, a strong silver ligand. The results show a higher accumulation of Ag in roots and leaves after exposure to AgNPs compared to AgNO3. This was correlated with a predominantly higher impact of nanoparticle than ionic silver form on parameters of oxidative stress, although no severe damage to important biomolecules was observed. Nevertheless, all types of treatments caused mobilization of antioxidant machinery, especially in leaves, although surface coatings modulated the activation of its specific components. Most effects induced by AgNPs or AgNO3 were alleviated with addition of cysteine.

Influence of Silver Nanoparticles on the Metabolites of Two Transgenic Soybean Varieties: An NMR-Based Metabolomics Approach

“…As a main observation, AgNPs coated with citrate showed the greatest tendency toward instability as an aggregation process. The same AgNP-coating behavior was discussed by Košpić et al during the investigation of the uptake of AgNPs by the tobacco plant. Therefore, understanding this behavior related to nanoparticle coating can support experiments involving nanoparticles and biological systems.…”

“…This was correlated with a predominantly greater impact of silver in NP than silver in ionic form on oxidative stress parameters, although no serious damage to important biomolecules was observed. 37 As reported by Galazzi et al, 1 nontransgenic and transgenic soybean plants cultivated with AgNPs and AgNO 3 accumulate a significant amount of silver in the aerial parts (stem and leaves). The translocation rate for RR soybean plants with AgNPs and AgNO 3 was around 100 and 65%, respectively, of the Ag + assimilated by the roots that were translocated to the aerial parts.…”

“…39 The results indicate that for different plant organs, specific responses occur to deal with oxidative stress induced by Ag. 37 Another hypothesis is that this result may be associated with the coated surface of the nanoparticle. In this case, the AgNPs used in this work are stabilized with citrate, and their mechanism is based on charge repulsion.…”

“…16 Comparing the response of roots and shoots, all treatments tested induced a stronger prominent effect on roots, corroborating a much greater accumulation of AgNPs in roots than in leaves. 1 A study carried out with tobacco plants (Nicotiana tabacum) grown in vitro 37 involved exposure to AgNPs, as well as ionic silver (AgNO 3 ), applied in the same concentrations, alone or in combination with cysteine, a strong silver ligand, reported a greater accumulation of Ag + in roots and leaves after exposure to AgNPs compared to AgNO 3 . This was correlated with a predominantly greater impact of silver in NP than silver in ionic form on oxidative stress parameters, although no serious damage to important biomolecules was observed.…”

Classification, uptake, translocation, and detection methods of nanoparticles in crop plants: a review

“…Košpić et al treated tobacco roots with AgNPs with different surface coatings found that AgNP–PVP treatment increased superoxide dismutase (SOD) activity and proline content, while AgNP–CTAB activated more catalase (CAT) and ascorbate peroxidase (APX). 98 Different types of NPs have different effects on different indicators of plants. Yin et al found that smaller AgNP particles (6 nm) more strongly affected plant growth than similar concentrations of larger (25 nm) particles.…”