Size Fractionation of Titania Nanoparticles in Wild Dittrichia viscosa Grown in a Native Environment

Foliar Uptake and Distribution of Metallic Oxide Nanoparticles in Maize (Zea mays L.) Leaf

The foliar uptake of Fe3O4, Cr2O3, CuO, and ZnO nanoparticles (NPs) by maize (Zea mays L.) was studied in a lab-scale experiment. The significant increase of Fe concentrations in leaves exposed to Fe3O4 was observed in both stomatal closing and stomatal opening treatments, suggesting the presence of a nonstomatal uptake. In parallel treatments with equal doses of Fe3O4 (∼200 nm), Cr2O3 (∼300 nm), CuO (∼30 nm), and ZnO (∼40 nm) (20-200 μg), the retention percentage of Fe in the leaves (21.0-69.0%) was higher than that of Cr, Cu, and Zn (0.5-14.0%). The steric hindrance effect seems more important for NPs of >200 nm, while hydrophobic surface and negative charge promote the foliar uptake of NPs smaller than 200 nm. The accumulation of NPs in the cuticle was observed through dark-field hyperspectral microscopy. Cr2O3, Fe3O4, and CuO NPs were difficult to penetrate the cuticle. In comparison, ZnO further migrated and distributed within the extracellular space of epidermal and mesophyll cells of the exposed leaf, possibly due to its comparatively higher solubility and hydrophilicity. The findings highlight the potential of the nonstomatal uptake, which might be a critical route for metallic oxide NPs to enter the food chain.

Comprehensive framework for overcoming scientific challenges related to assessing radioactive ultra-fine (nano/micro) particles transfer at the atmosphere-leaf interface

Food products are prone into contamination after a nuclear emission of radionuclides. While the mechanisms of emission and deposition of ultrafine radioactive particles are well documented, the transfer of these species from the atmosphere into plants is poorly assessed. This is evident in the lack of quantification of particles distributed within plants, especially regarding particles physical-chemical criteria to plant of different properties. Such knowledge gaps raise the concern about the representativeness of risk assessment tools designed for the transfer evaluation of ionic/soluble species to be qualified for simulating insoluble species exposure and proposes a possible underestimation. This highlights the possible need for special particle codes development to be implemented in models for future emissions. In addition, the later tools utilize transfer factors aggregating relevant sub-processes, suggesting another weak point in their overall reliability. As researchers specialized in the nuclear safety and protection, we intend in this perspective, to develop a compressive analysis of the interaction of ultrafine particles with plants of different specificities at different level processes starting from particles retention and gradual translocation to sink organs. This analysis is leveraged in providing insights for possible improvements in the current modeling tools for better real-life scenarios representation.

Bioavailability and translocation of platinum nanoparticles and platinum ions in rice (Oryza sativa L.): Nanoparticles biosynthesis and size-dependent transformation

Metal nanoparticles accumulation and bioavailability in plants raised much attention, specifically transformation and transportation of nanoparticles and their corresponding ions in plants are still unknown. In this work, rice seedlings were exposed to platinum nanoparticles (PtNPs) (with three sizes of 25, 50, and 70 nm) and Pt ions (with doses of 1, 2, and 5 mg/L) to investigate the influences of particle size and Pt form on bioavailability and translocation mechanism of metal nanoparticles. Results based on single particle ICP-MS (SP-ICP-MS) demonstrated the biosynthesis of PtNPs in Pt ions treated rice seedlings. The particle size ranges at 75-79.3 nm were detected in Pt ions exposed rice roots, and further migrated up to rice shoots at 21.7-44.3 nm. After exposed to PtNP-25, the particles could transfer to shoots with the original size distribution detected in roots, even with the PtNPs dose change. PtNP-50 and PtNP-70 translocated to shoots with the particle size increase. For the rice exposure with three dose levels, PtNP-70 had the highest number-based bioconcentration factors (NBCFs) in all Pt species, while Pt ions had the highest bioconcentration factors (BCFs), a range of 1.43-2.04. All PtNPs and Pt ions could be accumulated in rice plants and further transferred to shoots, and particle biosynthesis was proved through SP-ICP-MS. The finding could help us better understand the influence of particle size and form on the transformations of PtNPs in environment.

Uptake of TiO2 Nanoparticles was Linked to Variation in net Cation flux in Wheat Seedlings

Titanium dioxide nanoparticles (TiO₂ NPs) are ubiquitous in the environment and enter the terrestrial food chain via plant uptake. However, plant uptake behaviors of TiO₂ NPs remain elusive. Here, the uptake kinetics of TiO₂ NPs by wheat (Triticum aestivum L.) seedlings and the effects on cation flux in roots were examined in a hydroponic system. Uptake rate of TiO₂ NPs ranged from 119.0 to 604.2 mg kg^- 1 h^- 1 within 8 h exposure. NP uptake decreased by 83% and 47%, respectively, in the presence of sodium azide (NaN₃) and carbonyl cyanide m-chlorophenylhydrazone (CCCP), indicating an energy-dependent uptake of TiO₂ NPs. Moreover, accompanied with TiO₂ NP uptake, net influx of Cd²⁺ decreased by 81%, while Na⁺ flux shifted from inflow to outflow at the meristematic zone of root. These findings provide valuable information for understanding plant uptake of TiO₂ NPs.

Nano-enabled pesticides for sustainable agriculture and global food security

Achieving sustainable agricultural productivity and global food security are two of the biggest challenges of the new millennium. Addressing these challenges requires innovative technologies that can uplift global food production, while minimizing collateral environmental damage and preserving the resilience of agroecosystems against a rapidly changing climate. Nanomaterials with the ability to encapsulate and deliver pesticidal active ingredients (AIs) in a responsive (for example, controlled, targeted and synchronized) manner offer new opportunities to increase pesticidal efficacy and efficiency when compared with conventional pesticides. Here, we provide a comprehensive analysis of the key properties of nanopesticides in controlling agricultural pests for crop enhancement compared with their non-nanoscale analogues. Our analysis shows that when compared with non-nanoscale pesticides, the overall efficacy of nanopesticides against target organisms is 31.5% higher, including an 18.9% increased efficacy in field trials. Notably, the toxicity of nanopesticides toward non-target organisms is 43.1% lower, highlighting a decrease in collateral damage to the environment. The premature loss of AIs prior to reaching target organisms is reduced by 41.4%, paired with a 22.1% lower leaching potential of AIs in soils. Nanopesticides also render other benefits, including enhanced foliar adhesion, improved crop yield and quality, and a responsive nanoscale delivery platform of AIs to mitigate various pressing biotic and abiotic stresses (for example, heat, drought and salinity). Nonetheless, the uncertainties associated with the adverse effects of some nanopesticides are not well-understood, requiring further investigations. Overall, our findings show that nanopesticides are potentially more efficient, sustainable and resilient with lower adverse environmental impacts than their conventional analogues. These benefits, if harnessed appropriately, can promote higher crop yields and thus contribute towards sustainable agriculture and global food security.

Exposure Route of TiO2 NPs from Industrial Applications to Wastewater Treatment and Their Impacts on the Agro-Environment

The tremendous increase in the production and consumption of titanium dioxide (TiO2) nanoparticles (NPs) in numerous industrial products and applications has augmented the need to understand their role in wastewater treatment technologies. Likewise, the deleterious effects of wastewater on the environment and natural resources have compelled researchers to find out most suitable, economical and environment friendly approaches for its treatment. In this context, the use of TiO2 NPs as the representative of photocatalytic technology for industrial wastewater treatment is coming to the horizon. For centuries, the use of industrial wastewater to feed agriculture land has been a common practice across the globe and the sewage sludge generated from wastewater treatment plants is also used as fertilizer in agricultural soils. Therefore, it is necessary to be aware of possible exposure pathways of these NPs, especially in the perspective of wastewater treatment and their impacts on the agro-environment. This review highlights the potential exposure route of TiO2 NPs from industrial applications to wastewater treatment and its impacts on the agro-environment. Key elements of the review present the recent developments of TiO2 NPs in two main sectors including wastewater treatment and the agro-environment along with their potential exposure pathways. Furthermore, the direct exposure routes of these NPs from production to end-user consumption until their end phase needs to be studied in detail and optimization of their suitable applications and controlled use to ensure environmental safety.