Green nanochemistry: metal oxide nanoparticles and porous thin films from bare metal powders

Nano molybdenum trioxide-mediated enhancement of soybean yield through improvement of rhizosphere soil molybdenum bioavailability for nitrogen-fixing microbial recruitment

Molybdenum (Mo) plays a pivotal role in the growth and nitrogen-fixing process of plants mediated by rhizobia. However, the influence of nano‑molybdenum trioxide (MoO3NPs) on soybean growth, rhizosphere bioavailable Mo, and nitrogen-fixing microorganisms remains underexplored. Here, we report that compared with that of ionic Mo and bulk MoO3, the utilization of MoO3NPs (specifically NPs0.05 and NPs0.15) significantly boosted the available Mo content in the rhizosphere soil throughout the seedling (by 21.64 %-101.38 %), podding (by 54.44 %-68.89 %), and mature stage (by 34.41 %-to 45.71 %) of soybean growth. Furthermore, both NPs0.05 and NPs0.15 treatments maintained consistently higher levels of acid-extractable Mo, reducible Mo, and oxidizable Mo across these stages, which facilitated stable conversion and supply of bioavailable Mo. Within the rhizosphere soil, NPs0.05 and NPs0.15 treatments resulted in the highest relative abundance of Rhizobiales and Bradyrhizobium genera, and significantly promoted the colonization of nitrogen-fixing microorganisms, thereby increasing the content of nitrate nitrogen (NO3--N) by 8.69 % and 7.72 % and ammonium nitrogen (NH4+-N) by 44.75 % and 17.55 %, respectively. Ultimately, these effects together contributed to 107.17 % and 84.00 % increment in soybean yield by NPs0.05 and NPs0.15 treatments, respectively. In summary, our findings underscore the potential of employing MoO3NPs to promote plant growth and maintain soil nitrogen cycling, indicating distinct advantages of MoO3NPs over ionic Mo and bulk MoO3.

Room-temperature synthesis of three-dimensional porous ZnO@CuNi hybrid magnetic layers with photoluminescent and photocatalytic properties

A facile synthetic approach to prepare porous ZnO@CuNi hybrid films is presented. Initially, magnetic CuNi porous layers (consisting of phase separated CuNi alloys) are successfully grown by electrodeposition at different current densities using H2 bubbles as a dynamic template to generate the porosity. The porous CuNi alloys serve as parent scaffolds to be subsequently filled with a solution containing ZnO nanoparticles previously synthesized by sol-gel. The dispersed nanoparticles are deposited dropwise onto the CuNi frameworks and the solvent is left to evaporate while the nanoparticles impregnate the interior of the pores, rendering ZnO-coated CuNi 3D porous structures. No thermal annealing is required to obtain the porous films. The synthesized hybrid porous layers exhibit an interesting combination of tunable ferromagnetic and photoluminescent properties. In addition, the aqueous photocatalytic activity of the composite is studied under UV-visible light irradiation for the degradation of Rhodamine B. The proposed method represents a fast and inexpensive approach towards the implementation of devices based on metal-semiconductor porous systems, avoiding the use of post-synthesis heat treatment steps which could cause deleterious oxidation of the metallic counterpart, as well as collapse of the porous structure and loss of the ferromagnetic properties.

Single step in situ formation of porous zinc oxide/PMMA nanocomposites by pulsed laser irradiation: kinetic aspects and mechanisms

Simultaneous localizedin situformation of ZnO nanoparticles and porous structure in PMMA matrix by laser induced process.

On the self-assembly of TiOx into 1D NP network nanostructures

Here, we report for the first time a 'ligand free' method of designing 1D TiOx supramolecular network materials, which starts from Ti bare metal powder. Each TiOx oxidation step has been carefully investigated with different analytical techniques, including high resolution transmission electron microscopy/high resolution scanning electron microscopy (HRTEM/HRSEM), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy and superconducting quantum interference device (SQUID) measurements. The self-assembly of TiOx nanoparticles (NPs) into 1D supramolecular nanoparticle networks is induced by the formation of mixed valent Ti(II,III) species. The synthesis starts with etching a bare Ti surface, followed by a continuous oxidation of TiOx clusters and NPs, and it finally ends with the self-assembly into rigid 1D NPs chains. Today, such self-assembled 1D NP TiOx network materials are bridging the gap between the nanoscale and the macroscopic material world and will further provide interesting research opportunities.

A comprehensive review on synthesis methods for transition-metal oxide nanostructures

Recent developments of transition-metal oxide nanostructures with designed shape and dimensionality, including various synthesis methods and applications, are presented.

Molybdenum trioxide nanoparticles with intrinsic sulfite oxidase activity

Sulfite oxidase is a mitochondria-located molybdenum-containing enzyme catalyzing the oxidation of sulfite to sulfate in the amino acid and lipid metabolism. Therefore, it plays a major role in detoxification processes, where defects in the enzyme cause a severe infant disease leading to early death with no efficient or cost-effective therapy in sight. Here we report that molybdenum trioxide (MoO3) nanoparticles display an intrinsic biomimetic sulfite oxidase activity under physiological conditions, and, functionalized with a customized bifunctional ligand containing dopamine as anchor group and triphenylphosphonium ion as targeting agent, they selectively target the mitochondria while being highly dispersible in aqueous solutions. Chemically induced sulfite oxidase knockdown cells treated with MoO3 nanoparticles recovered their sulfite oxidase activity in vitro, which makes MoO3 nanoparticles a potential therapeutic for sulfite oxidase deficiency and opens new avenues for cost-effective therapies for gene-induced deficiencies.

Immunomodulatory activity of zinc peroxide (ZnO₂) and titanium dioxide (TiO₂) nanoparticles and their effects on DNA and protein integrity

Nanoparticles that are made from zinc and titanium oxide have found widespread applications, including their use in sunscreens. However, there is little information regarding their effects on immune cells. In the current study, we synthesized charge stabilized and "ligand free" colloid stable ZnO₂ and TiO₂ nanoparticles. Most previous published studies commonly used ZnO and TiO₂ nanoparticles. In the current study we investigated the comparative toxicity of ZnO₂ and TiO₂ nanoparticles. Therefore, our results based on ZnO₂ which is more oxidative than ZnO provides novel data on the possible toxicity of this species of nanoparticles. First, we investigated the immunomodulatory action of these nanoparticles on human peripheral blood mononuclear cells and their effects on DNA and protein integrity. A minimum concentration of ZnO₂ nanoparticles of 1 μg/mL inhibited the production of two inflammatory cytokines: interleukin-1-β and interleukin 6 by peripheral blood mononuclear cells in the presence of lipopolysaccharides. On the other hand, TiO₂ nanoparticles at a concentration range of 0.1-100 μg/mL did not present apparent toxicity to the peripheral blood mononuclear cells. ZnO₂ nanoparticles at a minimum concentration of 2 μg/mL caused DNA damage in vitro. TiO₂ nanoparticles at a concentration range of 25-100 μg/mL only caused marginal DNA damage. ZnO₂ nanoparticles at a minimum concentration of 5 μg/mL were capable of promoting aggregation of malate dehydrogenase, and facilitated its degradation at higher concentrations. Exposure of malate dehydrogenase to TiO₂ at a concentration range of 2.5-15 μg/mL did not alter the solubility of malate dehydrogenase. Altogether, our findings suggest that charge stabilized ZnO₂ nanoparticles are nascent and interact with DNA and protein and may be harmful to immune cells. In addition, the propensity of ZnO₂ nanoparticles to promote protein aggregation could facilitate the production of protein complexes that may interfere with normal immune functions.