Coating-Dependent Effects of Silver Nanoparticles on Tobacco Seed Germination and Early Growth

Abstract

Silver nanoparticles (AgNPs) are used in a wide range of consumer products because of their excellent antimicrobial properties. AgNPs released into the environment are prone to transformations such as aggregation, oxidation, or dissolution so they are often stabilised by coatings that affect their physico-chemical properties and change their effect on living organisms. In this study we investigated the stability of polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB) coated AgNPs in an exposure medium, as well as their effect on tobacco germination and early growth. AgNP-CTAB was found to be more stable in the solid Murashige and Skoog (MS) medium compared to AgNP-PVP. The uptake and accumulation of silver in seedlings was equally efficient after exposure to both types of AgNPs. However, AgNP-PVP induced only mild toxicity on seedlings growth, while AgNP-CTAB caused severe negative effects on all parameters, even compared to AgNO3. Moreover, CTAB coating itself exerted negative effects on growth. Cysteine addition generally alleviated AgNP-PVP-induced negative effects, while it failed to improve germination and growth parameters after exposure to AgNP-CTAB. These results suggest that the toxic effects of AgNP-PVP are mainly a consequence of release of Ag+ ions, while phytotoxicity of AgNP-CTAB can rather be ascribed to surface coating itself.

Phytotoxicity of Silver Nanoparticles on Tobacco Plants: Evaluation of Coating Effects on Photosynthetic Performance and Chloroplast Ultrastructure

“…Stability analyses showed that AgNP-CTAB kept their positive charge in a liquid ½ strength MS medium; on the contrary, the negative ζ potential of AgNP-citrate decreased slightly, while the ζ potential became even more negative with time for AgNP-PVP. Studies have already shown that positively charged AgNP-CTAB had a more severe impact on plant growth [ 19 ] and appearance of oxidative stress [ 18 ] than negatively charged citrate or non-ionic PVP coatings, probably due to attachment of positively charged AgNPs to the negatively charged plant cell walls. Significantly higher toxicity of positively charged AgNP-cystamine compared to AgNP-citrate was also reported for wheat calli [ 64 ].…”

“…Syntheses of AgNPs coated with polyvinylpyrrolidone (AgNP-PVP) and cetyltrimethylammonium bromide (AgNP-CTAB) were performed as reported by Biba et al [ 19 ] with minor modifications. Briefly, similar to citrate-capped AgNPs, synthesis of PVP-coated AgNP was carried out by adding 5 mL of a 1% ( w / v ) sodium citrate solution to 120 mL ultrapure water to which PVP (0.019 g, average molecular weight 40 × 10 3 g mol −1 ) and AgNO 3 (0.02 g) had been previously added.…”

“…Analyses of physical and chemical characteristics of citrate-, PVP-, and CTAB-coated AgNP stock solutions in ultrapure water were mainly performed as reported by Peharec Štefanić et al [ 12 ] and Biba et al [ 19 ]. AgNP formation was confirmed by the presence of a surface plasmon resonance (SPR) peak using a UV-Vis spectrophotometer (Unicam, Cheshire, UK).…”

“…AgNPs can impose both positive [ 14 , 15 ] and negative impacts [ 16 , 17 ] on plant growth and metabolism, which is found to be dependent on various factors, including the plant species, age, and tissue type [ 13 ]. Furthermore, the characteristics of AgNPs such as size, concentration, and charge [ 18 , 19 ] as well as the experimental conditions including duration and method of exposure [ 20 , 21 , 22 ] also play significant roles, influencing the stability of AgNPs and their susceptibility to transformation [ 19 , 23 ]. In recent studies, it was revealed that AgNP stability is also dependent on the composition and type of the exposure medium [ 24 , 25 ].…”

Influence of Silver Nanoparticles on the Biological Indicators of Haplic Chernozem

“…Matsum. and Nakai), and zucchini (Cucurbita pepo L.) [26][27][28][29][30][31]. However, the ecological effects of soil pollution with AgNPs were studied poorly compared to the nanosized of other metal-based NPs, such as iron, nickel, zinc, and copper [32][33][34].…”