Morphology-dependent antimicrobial activity of Cu/CuxO nanoparticles

Application of an Antibacterial Coating Layer via Amine-Terminated Hyperbranched Zirconium-Polysiloxane for Stainless Steel Orthodontic Brackets

The massive growth of various microorganisms on the orthodontic bracket can form plaques and cause diseases. A novel amine-terminated hyperbranched zirconium-polysiloxane (HPZP) antimicrobial coating was developed for an orthodontic stainless steel tank (SST). After synthesizing HPZP and HPZP-Ag coatings, their structures were characterized by nuclear magnetic resonance spectroscopy, scanning electron microscopy, thickness measurement, contact angle detection, mechanical stability testing, and corrosion testing. The cell toxicity of the two coatings to human gingival fibroblasts (hGFs) and human oral keratinocytes (hOKs) was detected by cell counting kit eight assays, and SST, HPZP@SST, and HPZP-Ag@SST were cocultured with Staphylococcus aureus, Escherichia coli, and Streptococcus mutans for 24 hr to detect the antibacterial properties of the coatings, respectively. The results show that the coatings are about 10 μm, and the water contact angle of HPZP coating is significantly higher than that of HPZP-Ag coating (P < 0.01). Both coatings can be uniformly and densely distributed on SST and have good mechanical stability and corrosion resistance. The cell counting test showed that HPZP coating and HPZP-Ag coating were less toxic to cells compared with SST, and the toxicity of HPZP-Ag coating was greater than that of HPZP coating, with the cell survival rate greater than 80% after 72 hr cocultured with hGFs and hOKs. The antibacterial test showed that the number of bacteria on the surface of different materials was ranked from small to large: HPZP@SST < HPZP-Ag@SST < SST and 800 μg/mL HPZP@SST showed a better bactericidal ability than 400 μg/mL after cocultured with S. aureus, E. coli, and S. mutans, respectively (all P < 0.05). The results showed that HPZP coating had a better effect than HPZP-Ag coating, with effective antibacterial and biocompatible properties, which had the potential to be applied in orthodontic process management.

Antimicrobial Activity of Morphology-Controlled Cu2O Nanoparticles: Oxidation Stability under Humid and Thermal Conditions

Metal oxides can be used as antimicrobial agents, especially since they can be fabricated into various forms such as films, masks, and filters. In particular, the durability of antimicrobial agents and the duration of their antimicrobial activity are important factors that determine their suitability for a specific purpose. These factors are related to the morphology and size of particles. The metal oxide Cu2O is often oxidized to CuO in various conditions, which reduces its antimicrobial activity. This study focused on the oxidation of nanoparticles of Cu2O with three morphologies, namely, spherical, octahedral, and cubic morphologies, in excessively humid and excessive-thermal environments for a specific duration and the antimicrobial activity of the NPs. Cu2O nanoparticles were prepared using the chemical reduction method, and their morphology could be varied by adjusting the molar ratio of OH- to Cu2+ and changing the reducing agent. It was found that cubic Cu2O was the most stable against oxidation and had the smallest reduction in antimicrobial activity. This study examined the antimicrobial activity and the oxidation stability of Cu2O NPs with different morphologies but similar particle sizes.

Antifungal Activity of Copper Oxide Nanoparticles against Root Rot Disease in Cucumber

Metal oxide nanoparticles have recently garnered interest as potentially valuable substances for the management of plant diseases. Copper oxide nanoparticles (Cu2ONPs) were chemically fabricated to control root rot disease in cucumbers. A scanning electron microscope (SEM), X-ray diffraction (XRD) and photoluminescence (PL) were employed to characterize the produced nanoparticles. Moreover, the direct antifungal activity of Cu2ONPs against Fusarium solani under laboratory, greenhouse, and field conditions were also evaluated. In addition, the induction of host-plant resistance by Cu2ONPs was confirmed by the results of enzyme activities (catalase, peroxidase, and polyphenoloxidase) and gene expression (PR-1 and LOX-1). Finally, the effect of Cu2ONPs on the growth and productivity characteristics of the treated cucumber plants was investigated. The average particle size from all the peaks was found to be around 25.54 and 25.83 nm for 0.30 and 0.35 Cu2O, respectively. Under laboratory conditions, the study found that Cu2ONPs had a greater inhibitory effect on the growth of Fusarium solani than the untreated control. Cu2ONP treatment considerably reduced the disease incidence of the root rot pathogen in cucumber plants in both greenhouse and field environments. Defense enzyme activity and defense genes (PR1 and LOX1) transcription levels were higher in cucumber plants treated with Cu2ONPs and fungicide than in the untreated control. SEM analysis revealed irregularities, changes, twisting, and plasmolysis in the mycelia, as well as spore shrinking and collapsing in F. solani treated with Cu2ONPs, compared to the untreated control. The anatomical analysis revealed that cucumber plants treated with Cu2ONPs had thicker cell walls, root cortex, and mesophyll tissue (MT) than untreated plants. Cucumber growth and yield characteristics were greatly improved after treatment with Cu2ONPs and fungicide. To the best of our knowledge, employing Cu2ONPs to treat cucumber rot root disease is a novel strategy that has not yet been reported.

Copper-containing nanoparticles: Mechanism of antimicrobial effect and application in dentistry-a narrative review

Copper has been used as an antimicrobial agent long time ago. Nowadays, copper-containing nanoparticles (NPs) with antimicrobial properties have been widely used in all aspects of our daily life. Copper-containing NPs may also be incorporated or coated on the surface of dental materials to inhibit oral pathogenic microorganisms. This review aims to detail copper-containing NPs' antimicrobial mechanism, cytotoxic effect and their application in dentistry.

Antifungal Effect of Copper Nanoparticles against Fusarium kuroshium, an Obligate Symbiont of Euwallacea kuroshio Ambrosia Beetle

Copper nanoparticles (Cu-NPs) have shown great antifungal activity against phytopathogenic fungi, making them a promising and affordable alternative to conventional fungicides. In this study, we evaluated the antifungal activity of Cu-NPs against Fusarium kuroshium, the causal agent of Fusarium dieback, and this might be the first study to do so. The Cu-NPs (at different concentrations) inhibited more than 80% of F. kuroshium growth and were even more efficient than a commercial fungicide used as a positive control (cupric hydroxide). Electron microscopy studies revealed dramatic damage caused by Cu-NPs, mainly in the hyphae surface and in the characteristic form of macroconidia. This damage was visible only 3 days post inoculation with used treatments. At a molecular level, the RNA-seq study suggested that this growth inhibition and colony morphology changes are a result of a reduced ergosterol biosynthesis caused by free cytosolic copper ions. Furthermore, transcriptional responses also revealed that the low- and high-affinity copper transporter modulation and the endosomal sorting complex required for transport (ESCRT) are only a few of the distinct detoxification mechanisms that, in its conjunction, F. kuroshium uses to counteract the toxicity caused by the reduced copper ion.

Synthesis and Investigation of Antimicrobial Activity of Cu2O Nanoparticles/Zeolite

Cuprous oxide (Cu2O) nanoparticles in zeolite A were synthesized by two steps: (i) ion-exchange of copper ions into the zeolite and (ii) reduction of copper ions in cages of the zeolite by hydrazine hydrate in base medium. The Cu2O nanoparticles/zeolite product was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The particle size of Cu2O nanoparticles was of 40 nm. The antibacterial activity of the as-synthesized Cu2O nanoparticles/zeolite against Escherichia coli was also investigated. Cu2O NPs/zeolite product can be favorably produced on large scale for water treatment and agricultural application as antimicrobial agent.

Fate and toxic effects of environmental stressors: environmental control

The potential for toxicants to harm organisms in the environment is influenced by the physicochemistry of the substances and their environmental behaviors and transformation within ecosystems. This special issue is composed of 20 papers that report on studies which have investigated the fate and toxicity of various toxicants including engineered nanoparticles, pharmaceuticals and personal care products, antibiotics, pathogens, heavy metals, and agricultural nutrients. The environmental transformations of these substances and how these processes affect their toxicity are emphasized. This paper highlights the important findings and perspectives of the selected papers in this special edition, with an aim of providing insights into full-scale evaluation on the toxicity of various contaminants that exist in ecosystems. General suggestions are provided for the future directions of toxicological research.