Toxicity of Nanoparticulate Nickel to Aquatic Organisms: Review and Recommendations for Improvement of Toxicity Tests

Ecotoxicology of Polymetallic Nodule Seabed Mining: The Effects of Cobalt and Nickel on Phytoplankton Growth and Pigment Concentration

In order to improve the understanding of the environmental impacts of polymetallic nodule mining, ecotoxicological studies were conducted on the growth of model phytoplankton species Skeletonema costatum and Prorocentrum donghaiense using cobalt and nickel. This study evaluated various physiological and ecological indicators, such as cell proliferation, chlorophyll a, pigments, total protein, and antioxidant enzyme markers. The results show that the introduction of low amounts of cobalt or nickel increased the growth rate of phytoplankton. The phytoplankton benefited from low concentrations of cobalt and nickel stress. The increased protein levels and decreased activity of antioxidant enzymes considerably impacted physiological responses during the promotion of cell abundance. High concentrations of cobalt or nickel resulted in decreased light-absorbing pigments, increased photoprotective pigments, an inactive chlorophyll content, decreased total proteins, and maximal antioxidant enzyme activity in phytoplankton. Throughout the experiment, both the phytoplankton protein and enzyme activity declined with prolonged stress, and the cells underwent age-induced damage. Thus, seabed mining's repercussions on phytoplankton could result in both short-term growth promotion and long-term damage. These consequences depend on the impurity concentrations infiltrating the water, their duration, and the organism's physiological responses.

Materials and interfaces properties optimization for high-efficient and more stable RbGeI3 perovskite solar cells: optoelectrical modelling

In this research work, we investigated the effects of a broad set of materials properties and external operating parameters on the opto-electrical output of a hybrid RbGeI3-based perovskite solar cell (PSC) as a means of enhancing its performance. We first performed a judicious numerical modelling of the reference cell with the following structure FTO/TiO2/RbGeI3/Spiro-OMeTAD/Ag, with data retrieved from the experiment. SCAPS program enables to model the device, considering charge carriers transport governing equations. Investigations are directed on addressing the current challenges that include thinner, less environmentally harmful, cost-effectiveness, and more stable solar devices over time. Analysis of the effects of different hole transport material (HTM) on current-voltage (J-V) and external quantum efficiency (QE) characteristics, helps to identify CuI as an ideal HTM. Optimal cell output were achieved by investigating the effects of metal contact work function, defect states, RbGeI3 thickness, light transmission/reflection at the front/back contact, as well as operating temperature. As a result, efficiency increased significantly from 10.11 to 18.10%, and fill factor that represents a stability indicator, increased from 63.68 to 76.95%. Moreover, an optimum open-circuit voltage Voc = 0.70 V and a high short-circuit current density of Jsc = 33.51 mA/cm2 were recorded. An additional study on the capture cross-section of charge carriers ([Formula: see text]) on PV characteristics, enabled to achieve a power conversion efficiency (PCE) of 29.71% and FF of 88% at a value of [Formula: see text] selected to be 10-22 cm2. This contribution aims at designing and producing thinner, more efficient, more stable and more environmentally clean and economically viable PSCs.

Hormetic dose responses induced by nickel oxide nanoparticles (NiONPs) on growth, biochemical, and antioxidant defense systems of Dracocephalum kotschyi

The application of nickel oxide nanoparticles (NiONPs) in various fields leads to their release into soil and water and, consequently, interaction with plants. Unlike its bulk counterpart, the phytotoxic potential of NiONPs is relatively less studied, particularly in a hormesis framework. Hormesis is an interesting phenomenon characterized by low-dose stimulation and high-dose inhibition. Therefore, this study demonstrates the stimulatory and inhibitory effects of NiONPs on Dracocephalum kotschyi Boiss as a medicinal plant cultivated in a pot experiment carried out in a greenhouse for 3 weeks. High bioaccumulation of nickel (Ni) in roots of treated plants relative to shoots indicates higher oxidative damage. NiONPs induced hormetic effects on photosynthetic pigments, as at low concentration of 50 mg/L stimulated chlorophyll (2.8-46.7%), carotenoid (16%), and anthocyanin (5.9%) contents and at higher concentrations inhibited the content of these pigments. A hormetic response was observed in growth parameters, i.e., NiONPs induced shoot height (7.2%) and weight (33%) at 100 mg/L, while inhibited shoot and root length (14.5-16.1% and 28.7-42.7%) and weight (46.8-48.1% and 37-40.6%), respectively, at 1000 and 2500 mg/L. The treated plants declined the toxic effects and oxidative stress caused by NiONPs by activating non-enzymatic antioxidants (phenolic compounds and proline) and enzymatic antioxidants, i.e., increasing the levels of SOD, POD, CAT, and APX. Therefore, the present study investigated for the first time the different mechanisms and responses of D. kotschyi plants to NiONPs in a wide range of concentrations. The results suggest that NiONPs may act as an elicitor at lower concentrations in medicinal plants according to specific conditions. However, these NPs at higher concentrations induce oxidative stress and harmful effects on plants, so their use poses serious risks to human health and the environment.

Nickel nanoparticles affect the migration and invasion of HTR-8/SVneo cells by downregulating MMP2 through the PI3K/AKT pathway

Proper migration and invasion of extravillous trophoblast cells into the endometrium in early gestation is essential for successful embryo implantation. The development of nanotechnology has led to the emergence of nickel nanoparticles (Ni NPs), for which attendant health concerns are widespread. Ni NPs are known to affect reproduction and be embryotoxic, but whether they affect the migration and invasion functions of trophoblast cells is unclear. We investigated the effects of Ni NPs on the migration and invasion of HTR-8/SVneo in extravillous trophoblast cells and explored the possible role of the PI3K/AKT/MMP2 signaling pathway in this regard. Results showed that the migration and invasion of cells was significantly inhibited by the exposure of Ni NPs. The protein and mRNA levels of PI3K/AKT/MMP2 signaling pathway were significantly reduced with the increase in Ni NPs concentration. The presence of the PI3K activator 740Y-P partially attenuated the inhibition of cell migration and invasion by Ni NPs, confirming the involvement of this pathway. Thus, Ni NPs inhibit migration and invasion of human trophoblast HTR-8/SVneo cells by downregulating the PI3K/AKT/MMP2 signaling pathway. This study is important for the development of safety evaluation criteria for Ni NPs.

Carbon Microsphere-Supported Metallic Nickel Nanoparticles as Novel Heterogeneous Catalysts and Their Application for the Reduction of Nitrophenol

Nickel nanoparticles are gaining increasing attention in catalysis due to their versatile catalytic action. A novel, low-cost and facile method was developed in this work to synthesize carbon microsphere-supported metallic nickel nanoparticles (Ni-NP/C) for heterogeneous catalysis. The synthesis was based on carbonizing a polystyrene-based cation exchange resin loaded with nickel ions at temperatures between 500 and 1000 °C. The decomposition of the nickel-organic framework resulted in both Ni-NP and carbon microsphere formation. The phase composition, morphology and surface area of these Ni-NP/C microspheres were characterized by powder X-ray diffraction, Raman spectroscopy, scanning electron microscopy and BET analysis. Elemental nickel was found to be the only metal containing phase; fcc-Ni coexisted with hcp-Ni at carbonization temperatures between 500 and 700 °C, and fcc-Ni was the only metallic phase at 800–1000 °C. Graphitization and carbon nanotube formation were observed at high temperatures. The catalytic activity of Ni-NP/C was tested in the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride, and Ni-NP/C was proved to be an efficient catalyst in this reaction. The relatively easy and scalable synthetic method, as well as the easy separation and catalytic activity of Ni-NP/C, provide a viable alternative to existing nickel nanocatalysts in future applications.

Harmful effects of metal(loid) oxide nanoparticles

Abstract

The incorporation of nanomaterials (NMs), including metal(loid) oxide (MOx) nanoparticles (NPs), in the most diversified consumer products, has grown enormously in recent decades. Consequently, the contact between humans and these materials increased, as well as their presence in the environment. This fact has raised concerns and uncertainties about the possible risks of NMs to human health and the adverse effects on the environment. These concerns underline the need and importance of assessing its nanosecurity. The present review focuses on the main mechanisms underlying the MOx NPs toxicity, illustrated with different biological models: release of toxic ions, cellular uptake of NPs, oxidative stress, shading effect on photosynthetic microorganisms, physical restrain and damage of cell wall. Additionally, the biological models used to evaluate the potential hazardous of nanomaterials are briefly presented, with particular emphasis on the yeast Saccharomyces cerevisiae, as an alternative model in nanotoxicology. An overview containing recent scientific advances on cellular responses (toxic symptoms exhibited by yeasts) resulting from the interaction with MOx NPs (inhibition of cell proliferation, cell wall damage, alteration of function and morphology of organelles, presence of oxidative stress bio-indicators, gene expression changes, genotoxicity and cell dead) is critically presented. The elucidation of the toxic modes of action of MOx NPs in yeast cells can be very useful in providing additional clues about the impact of NPs on the physiology and metabolism of the eukaryotic cell. Current and future trends of MOx NPs toxicity, regarding their possible impacts on the environment and human health, are discussed.

Key points

• The potential hazardous effects of MOx NPs are critically reviewed.

• An overview of the main mechanisms associated with MOx NPs toxicity is presented.

• Scientific advances about yeast cell responses to MOx NPs are updated and discussed.