Phytotoxicity of Silver Nanoparticles with Different Surface Properties on Monocots and Dicots Model Plants

Abstract

The aim of the research was to evaluate the effect of three types of silver nanoparticles (AgNPs) with different physicochemical properties and silver ions delivered in the form of silver nitrate (AgNO3) at the concentration of 50 mg L−1 on germination and initial growth of monocots (common wheat, sorghum) and dicots (garden cress, white mustard). The AgNPs were prepared using trisodium citrate (TCSB-AgNPs), tannic acid (TA-AgNPs), and cysteamine hydrochloride (CHSB-AgNPs). They exhibited comparable shape, size distribution, and an average size equal to 15 ± 3 nm which was confirmed with the use of transmission electron microscopy. The electrokinetic characteristics revealed that CHSB-AgNPs have positive, whereas TCSB-AgNPs and TA-AgNPs negative surface charge. First, toxicity of the silver compounds was assessed using the Phytotestkit test. Next, after transferring seedlings to pots, shoot length, leaf surface, shoot dry mass, electrolyte leakage measurement, and photosystem II (PSII) efficiency were determined. AgNPs and silver ions delivered in the form of AgNO3 reduced root and shoots length of common wheat, sorghum, and garden cress; leaves surface of garden cress and white mustard; and shoots dry mass of white mustard. The positively charged CHSB-AgNPs and silver ions delivered in the form of AgNO3 showed the greatest inhibition effect. Moreover, silver ions and positively charged CHSB-AgNPs were more toxic to PSII of model plants than negatively charged TCSB-AgNPs and TA-AgNPs. AgNPs impact differed in the case of monocots and dicots, but the size of the changes was not significant, so it concerned individual parameters. The results revealed the interaction strength, which was generally similar in all tested plants, i.e., increasing negative effect in sequence TCSB-AgNPs < TA-AgNPs < silver ions delivered in the form of AgNO3 < CHSB-AgNPs.

The Effect of Bio-Synthesized Silver Nanoparticles on Germination, Early Seedling Development, and Metabolome of Wheat (Triticum aestivum L.)

“…The small (8 nm) and spherical Ag NPs showed higher antimicrobial activity than larger (45–47 nm) as well as decahedral or triangular Ag NPs [ 26 ]. This is related to the fact that small Ag NPs particles can easily pass through pores in the cell walls of wheat root epidermis, enter the plasma membrane, reach the cortex tissues, and be transported by xylem [ 16 , 17 , 26 , 33 , 44 ].…”

“…Due to their small size and high surface activity, metallic NPs are mostly harmful to organisms as they readily cross biological membranes, exhibiting immediate or delayed toxic effects [ 12 , 13 ]. The effects of NPs on plants depend both on their chemical nature, size, shape, coating agents, and concentration, as well as on the plant species and its developmental stage [ 8 , 9 , 10 , 11 , 12 , 14 , 15 , 16 , 17 ]. Therefore, the safety of the use of metal NPs in crops requires detailed studies.…”

“…The results of recently published papers indicate that the practical use of NPs in wheat cultivation is still in the early stages of application. Some of the metal oxide NPs such as TiO 2 NPs and ZnO NPs, as well as Ag NPs, have been shown to enhance seed germination, plant growth, and the yield of wheat, but when applied at strictly selected concentrations [ 1 , 17 ]. Moreover, they can alleviate crop stress conditions such as drought, salinity, and heat [ 5 ], and they can control wheat pathogens [ 6 , 7 , 18 , 19 ] due to their antifungal, antiviral, and bactericidal properties [ 6 , 20 ].…”

“…For example, Ag NPs applied at the appropriate concentration can be equally or more effective compared to synthetic fungicides [ 21 ] or antibiotics [ 22 ]. However, too high a dose of Ag NPs is phytotoxic for monocots and dicots model plants [ 17 ] as well as crops [ 8 ]. Silver NPs show multiple modes of inhibitory action against microorganisms [ 23 ].…”

The Imbibition of Pea (Pisum sativum L.) Seeds in Silver Nitrate Reduces Seed Germination, Seedlings Development and Their Metabolic Profile

“…In recent years, there has been an increasing number of reports indicating the effects of Ag NPs on various plant species [ 9 , 10 ], including model plants [ 11 , 12 ] and economically important crops [ 13 , 14 , 15 ]. The effect of Ag NPs on plants depends on their size, shape, coating agents, concentration [ 16 ] and released Ag + ions [ 17 , 18 ].…”