Abstract
The rapid development of nanotechnology and its widespread use have given rise to serious concerns over the potential adverse impacts of nanomaterials on the Earth’s ecosystems. Among all the nanomaterials, silver nanoparticles (AgNPs) are one of the most extensively used nanomaterials due to their excellent antibacterial property. However, the toxic mechanism of AgNPs in nature is still unclear. One of the questions under debate is whether the toxicity is associated with the size of AgNPs or the silver ions released from AgNPs. In our previous study, a sub-micron hybrid sphere system with polydopamine-stabilized AgNPs (Ag@PDS) was synthesized through a facile and green method, exhibiting superior antibacterial properties. The current study aims to explore the unique toxicity profile of this hybrid sphere system by studying its effect on germination and early growth of Lolium multiflorum, with AgNO3 and 15 nm AgNPs as a comparison. The results showed the seed germination was insensitive/less sensitive to all three reagents; however, vegetative growth was more sensitive. Specifically, when the Ag concentration was lower than 40 mg/L, Ag@PDS almost had no adverse effects on the root and shoot growth of Lolium multiflorum seeds. By contrast, when treated with AgNO3 at a lower Ag concentration of 5 mg/L, the plant growth was inhibited significantly, and was reduced more in the case of AgNP treatment at the same Ag concentration. As the exposures of Ag@PDS, AgNO3, and AgNPs increased, so did the Ag content in the root and shoot. In general, Ag@PDS was proven to be a potential useful hybrid material that retains antibacterial property with light phytotoxicity.
Highlights
Nanoparticles (NPs) have attracted considerable interest due to their unique physicochemical properties compared with their bulk counterparts; they are applied in various fields such as water treatment, cosmetics, medicine, food, and so on [1,2]
AgNPs were uniform with the mean diameter of about 15 nm, Toxics 2021, 9, 151 whose size was similar to those AgNPs attached to the surface of polydopamine spheres (PDS) microspheres in Ag@PDS
At the vegetative growth stage, Ag@PDS almost had no adverse effect on the plant growth at a low concentration, while AgNO3 inhibited the growth slightly, and seeds exposed to AgNPs showed severely inhibited growth of roots and shoots
Summary
Nanoparticles (NPs) have attracted considerable interest due to their unique physicochemical properties compared with their bulk counterparts; they are applied in various fields such as water treatment, cosmetics, medicine, food, and so on [1,2]. There is increasing environmental exposure to nanoparticles, which happens during the life cycle of NPs, such as manufacturing, transporting, atmospheric emission, effluent discharge, and agricultural use, etc. It is urgent to explore the potential impacts of nanomaterials on the environment and human health. Over the past several decades, people care more about the toxicity and transportation of nanomaterials in the environment, and have begun to focus on the probable health harms to living organisms [3,4,5]. The toxicity of nanoparticles (TiO2, ZnO, Ag, Cu, Al, carbon nanotubes, and so on) to living species has been studied in a wide range, including algae, higher plants, animals, and even humans [6,7,8,9,10]. Atha et al proposed that copper oxide nanoparticles strongly inhibited grassland plant growth and induced DNA damage as well as cyanobacteria, which are ancient prokaryotic microorganisms, by generating excess formation of reactive oxygen substances (ROS) [11]
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