Effect of MnxOy Nanoparticles Stabilized with Methionine on Germination of Barley Seeds (Hordeum vulgare L.)

Effect of MnO2 Nanoparticles Stabilized with Cocamidopropyl Betaine on Germination and Development of Pea (Pisum sativum L.) Seedlings

This study aimed to synthesize, characterize, and evaluate the effect of cocamidopropyl betaine-stabilized MnO2 nanoparticles (NPs) on the germination and development of pea seedlings. The synthesized NPs manifested as aggregates ranging from 50-600 nm, comprising spherical particles sized between 19 to 50 nm. These particles exhibited partial crystallization, indicated by peaks at 2θ = 25.37, 37.62, 41.18, 49.41, 61.45, and 65.79°, characteristic of MnO2 with a tetragonal crystal lattice with a I4/m spatial group. Quantum chemical modelling showed that the stabilization process of MnO2 NPs with cocamidopropyl betaine is energetically advantageous (∆E > 1299.000 kcal/mol) and chemically stable, as confirmed by the positive chemical hardness values (0.023 ≤ η ≤ 0.053 eV). It was revealed that the interaction between the MnO2 molecule and cocamidopropyl betaine, facilitated by a secondary amino group (NH), is the most probable scenario. This ascertain is supported by the values of the difference in total energy (∆E = 1299.519 kcal/mol) and chemical hardness (η = 0.053 eV). These findings were further confirmed using FTIR spectroscopy. The effect of MnO2 NPs at various concentrations on the germination of pea seeds was found to be nonlinear and ambiguous. The investigation revealed that MnO2 NPs at a concentration of 0.1 mg/L resulted in the highest germination energy (91.25%), germinability (95.60%), and lengths of roots and seedlings among all experimental samples. However, an increase in the concentration of preparation led to a slight growth suppression (1-10 mg/L) and the pronounced inhibition of seedling and root development (100 mg/L). The analysis of antioxidant indicators and phytochemicals in pea seedlings indicated that only 100 mg/L MnO2 NPs have a negative effect on the content of soluble sugars, chlorophyll a/b, carotenoids, and phenols. Conversely, lower concentrations showed a stimulating effect on photosynthesis indicators. Nevertheless, MnO2 NPs at all concentrations generally decreased the antioxidant potential of pea seedlings, except for the ABTS parameter. Pea seedlings showed a notable capacity to absorb Mn, reaching levels of 586.5 μg/L at 10 mg/L and 892.6 μg/L at 100 mg/L MnO2 NPs, surpassing the toxic level for peas according to scientific literature. However, the most important result was the observed growth-stimulating activity at 0.1 mg/L MnO2 NPs stabilized with cocamidopropyl betaine, suggesting a promising avenue for further research.

Impact of nanopollution on plant growth, photosynthesis, toxicity, and metabolism in the agricultural sector: An updated review

Nanotechnology provides distinct benefits to numerous industrial and commercial fields, and has developed into a discipline of intense interest to researchers. Nanoparticles (NPs) have risen to prominence in modern agriculture due to their use in agrochemicals, nanofertilizers, and nanoremediation. However, their potential negative impacts on soil and water ecosystems, as well as plant growth and physiology, have caused concern for researchers and policymakers. Concerns have been expressed regarding the ecological consequences and toxicity effects associated with nanoparticles as a result of their increased production and usage. Moreover, the accumulation of nanoparticles in the environment poses a risk, not only because of the possibility of plant damage but also because nanoparticles may infiltrate the food chain. In this review, we have documented the beneficial and detrimental effects of NPs on seed germination, shoot and root growth, plant biomass, and nutrient assimilation. Nanoparticles exert toxic effects by inducing ROS generation and stimulating cytotoxic and genotoxic effects, thereby leading to cell death in several plant species. We have provided possible mechanisms by which nanoparticles induce toxicity in plants. In addition to the toxic effects of NPs, we highlighted the importance of nanomaterials in the agricultural sector. Thus, understanding the structure, size, and concentration of nanoparticles that will improve plant growth or induce plant cell death is essential. This updated review reveals the multifaceted connection between nanoparticles, soil and water pollution, and plant biology in the context of agriculture.

CuO Nanoparticles and Microaggregates: An Experimental and Computational Study of Structure and Electronic Properties

The link between morphology and properties is well-established in the nanoparticle literature. In this report, we show that different approaches in the synthesis of copper oxide can lead to nanoparticles (NPs) of different size and morphology. The structure and properties of the synthesized NPs are investigated with powder X-ray diffraction, scanning electron microscopy (SEM), and diffuse reflectance spectroscopy (DRS). Through detailed SEM analyses, we were able to correlate the synthetic pathways with the particles' shape and aggregation, pointing out that bare hydrothermal pathways yield mainly spheroidal dandelion-like aggregates, whereas, if surfactants are added, the growth of the nanostructures along a preferential direction is promoted. The effect of the morphology on the electronic properties was evaluated through DRS, which allowed us to obtain the electron bandgap in every system synthesized, and to find that the rearrangement of threaded particles into more compact structures leads to a reduction in the energy difference. The latter result was compared with Density Functional Theory (DFT) computational models of small centrosymmetric CuO clusters, cut from the tenorite crystal structure. The computed UV-Vis absorption spectra obtained from the clusters are in good agreement with experimental findings.