Hormetic Response of Photosystem II Function Induced by Nontoxic Calcium Hydroxide Nanoparticles.

In recent years, inorganic nanoparticles, including calcium hydroxide nanoparticles [Ca Ca(OH)2 NPs], have attracted significant interest for their ability to impact plant photosynthesis and boost agricultural productivity. In this study, the effects of 15 and 30 mg L-1 oleylamine-coated calcium hydroxide nanoparticles [Ca(OH)2@OAm NPs] on photosystem II (PSII) photochemistry were investigated on tomato plants at their growth irradiance (GI) (580 µmol photons m-2 s-1) and at high irradiance (HI) (1000 µmol photons m-2 s-1). Ca(OH)2@OAm NPs synthesized via a microwave-assisted method revealed a crystallite size of 25 nm with 34% w/w of oleylamine coater, a hydrodynamic size of 145 nm, and a ζ-potential of 4 mV. Compared with the control plants (sprayed with distilled water), PSII efficiency in tomato plants sprayed with Ca(OH)2@OAm NPs declined as soon as 90 min after the spray, accompanied by a higher excess excitation energy at PSII. Nevertheless, after 72 h, the effective quantum yield of PSII electron transport (ΦPSII) in tomato plants sprayed with Ca(OH)2@OAm NPs enhanced due to both an increase in the fraction of open PSII reaction centers (qp) and to the enhancement in the excitation capture efficiency (Fv'/Fm') of these centers. However, the decrease at the same time in non-photochemical quenching (NPQ) resulted in an increased generation of reactive oxygen species (ROS). It can be concluded that Ca(OH)2@OAm NPs, by effectively regulating the non-photochemical quenching (NPQ) mechanism, enhanced the electron transport rate (ETR) and decreased the excess excitation energy in tomato leaves. The delay in the enhancement of PSII photochemistry by the calcium hydroxide NPs was less at the GI than at the HI. The enhancement of PSII function by calcium hydroxide NPs is suggested to be triggered by the NPQ mechanism that intensifies ROS generation, which is considered to be beneficial. Calcium hydroxide nanoparticles, in less than 72 h, activated a ROS regulatory network of light energy partitioning signaling that enhanced PSII function. Therefore, synthesized Ca(OH)2@OAm NPs could potentially be used as photosynthetic biostimulants to enhance crop yields, pending further testing on other plant species.

Modification of Tomato Photosystem II Photochemistry with Engineered Zinc Oxide Nanorods.

We recently proposed the use of engineered irregularly shaped zinc oxide nanoparticles (ZnO NPs) coated with oleylamine (OAm), as photosynthetic biostimulants, to enhance crop yield. In the current research, we tested newly engineered rod-shaped ZnO nanorods (NRs) coated with oleylamine (ZnO@OAm NRs) regarding their in vivo behavior related to photosynthetic function and reactive oxygen species (ROS) generation in tomato (Lycopersicon esculentum Mill.) plants. ZnO@OAm NRs were produced via solvothermal synthesis. Their physicochemical assessment revealed a crystallite size of 15 nm, an organic coating of 8.7% w/w, a hydrodynamic diameter of 122 nm, and a ζ-potential of -4.8 mV. The chlorophyll content of tomato leaflets after a foliar spray with 15 mg L-1 ZnO@OAm NRs presented a hormetic response, with an increased content 30 min after the spray, which dropped to control levels 90 min after the spray. Simultaneously, 90 min after the spray, the efficiency of the oxygen-evolving complex (OEC) decreased significantly (p < 0.05) compared to control values, with a concomitant increase in ROS generation, a decrease in the maximum efficiency of PSII photochemistry (Fv/Fm), a decrease in the electron transport rate (ETR), and a decrease in the effective quantum yield of PSII photochemistry (ΦPSII), indicating reduced PSII efficiency. The decreased ETR and ΦPSII were due to the reduced efficiency of PSII reaction centers (Fv'/Fm'). There were no alterations in the excess excitation energy at PSII or the fraction of open PSII reaction centers (qp). We discovered that rod-shaped ZnO@OAm NRs reduced PSII photochemistry, in contrast to irregularly shaped ZnO@OAm NPs, which enhanced PSII efficiency. Thus, the shape and organic coating of the nanoparticles play a critical role in the mechanism of their action and their impact on crop yield when they are used in agriculture.

Impact of Coated Zinc Oxide Nanoparticles on Photosystem II of Tomato Plants.

Zinc oxide nanoparticles (ZnO NPs) have emerged as a prominent tool in agriculture. Since photosynthetic function is a significant measurement of phytotoxicity and an assessment tool prior to large-scale agricultural applications, the impact of engineered irregular-shaped ZnO NPs coated with oleylamine (ZnO@OAm NPs) were tested. The ZnO@OAm NPs (crystalline size 19 nm) were solvothermally prepared in the sole presence of oleylamine (OAm) and evaluated on tomato (Lycopersicon esculentum Mill.) photosystem II (PSII) photochemistry. Foliar-sprayed 15 mg L-1 ZnO@OAm NPs on tomato leaflets increased chlorophyll content that initiated a higher amount of light energy capture, which resulted in about a 20% increased electron transport rate (ETR) and a quantum yield of PSII photochemistry (ΦPSII) at the growth light (GL, 600 µmol photons m-2 s-1). However, the ZnO@OAm NPs caused a malfunction in the oxygen-evolving complex (OEC) of PSII, which resulted in photoinhibition and increased ROS accumulation. The ROS accumulation was due to the decreased photoprotective mechanism of non-photochemical quenching (NPQ) and to the donor-side photoinhibition. Despite ROS accumulation, ZnO@OAm NPs decreased the excess excitation energy of the PSII, indicating improved PSII efficiency. Therefore, synthesized ZnO@OAm NPs can potentially be used as photosynthetic biostimulants for enhancing crop yields after being tested on other plant species.

Nanocapsules of ZnO Nanorods and Geraniol as a Novel Mean for the Effective Control of Botrytis cinerea in Tomato and Cucumber Plants.

Inorganic-based nanoparticle formulations of bioactive compounds are a promising nanoscale application that allow agrochemicals to be entrapped and/or encapsulated, enabling gradual and targeted delivery of their active ingredients. In this context, hydrophobic ZnO@OAm nanorods (NRs) were firstly synthesized and characterized via physicochemical techniques and then encapsulated within the biodegradable and biocompatible sodium dodecyl sulfate (SDS), either separately (ZnO NCs) or in combination with geraniol in the effective ratios of 1:1 (ZnOGer1 NCs), 1:2 (ZnOGer2 NCs), and 1:3 (ZnOGer2 NCs), respectively. The mean hydrodynamic size, polydispersity index (PDI), and ζ-potential of the nanocapsules were determined at different pH values. The efficiency of encapsulation (EE, %) and loading capacity (LC, %) of NCs were also determined. Pharmacokinetics of ZnOGer1 NCs and ZnOGer2 NCs showed a sustainable release profile of geraniol over 96 h and a higher stability at 25 ± 0.5 °C rather than at 35 ± 0.5 °C. ZnOGer1 NCs, ZnOGer2 NCs and ZnO NCs were evaluated in vitro against B. cinerea, and EC50 values were calculated at 176 µg/mL, 150 µg/mL, and > 500 µg/mL, respectively. Subsequently, ZnOGer1 NCs and ZnOGer2 NCs were tested by foliar application on B. cinerea-inoculated tomato and cucumber plants, showing a significant reduction of disease severity. The foliar application of both NCs resulted in more effective inhibition of the pathogen in the infected cucumber plants as compared to the treatment with the chemical fungicide Luna Sensation SC. In contrast, tomato plants treated with ZnOGer2 NCs demonstrated a better inhibition of the disease as compared to the treatment with ZnOGer1 NCs and Luna. None of the treatments caused phytotoxic effects. These results support the potential for the use of the specific NCs as plant protection agents against B. cinerea in agriculture as an effective alternative to synthetic fungicides.

Fighting Phytopathogens with Engineered Inorganic-Based Nanoparticles.

The development of effective and ecofriendly agrochemicals, including bactericides, fungicides, insecticides, and nematicides, to control pests and prevent plant diseases remains a key challenge. Nanotechnology has provided opportunities for the use of nanomaterials as components in the development of anti-phytopathogenic agents. Indeed, inorganic-based nanoparticles (INPs) are among the promising ones. They may play an effective role in targeting and killing microbes via diverse mechanisms, such as deposition on the microbe surface, destabilization of cell walls and membranes by released metal ions, and the induction of a toxic mechanism mediated by the production of reactive oxygen species. Considering the lack of new agrochemicals with novel mechanisms of action, it is of particular interest to determine and precisely depict which types of INPs are able to induce antimicrobial activity with no phytotoxicity effects, and which microbe species are affected. Therefore, this review aims to provide an update on the latest advances in research focusing on the study of several types of engineered INPs, that are well characterized (size, shape, composition, and surface features) and show promising reactivity against assorted species (bacteria, fungus, virus). Since effective strategies for plant protection and plant disease management are urgently needed, INPs can be an excellent alternative to chemical agrochemical agents as indicated by the present studies.

Coated Cu-doped ZnO and Cu nanoparticles as control agents against plant pathogenic fungi and nematodes.

In the current study, coated copper nanoparticles with polyethylene glycol 8000 (Cu@PEG NPs) and copper-doped zinc oxide nanoparticles with diethylene glycol (Cu-doped ZnO@DEG NPs) have been synthesized via solvothermal and microwave-assisted process, physicochemical characterized, and studied as nano-fungicides and nano-nematicides. Spheroidal Cu-doped ZnO@DEG NPs and urchin-like Cu@PEG NPs have been isolated with average crystallite sizes of 12 and 21 nm, respectively. The Cu doping (11.3 wt%) in ZnO lattice (88.7 wt%) was investigated by Rietveld refinement analysis and confirmed by X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The Cu-doped ZnO@DEG and Cu@PEG NPs revealed a growth inhibition of fungi Botrytis cinerea (B. cinerea) and Sclerotinia sclerotiorum (S. sclerotiorum) and nematode paralysis of Meloidogyne javanica in a dose-dependent manner. Cu-doped ZnO@DEG NPs were more effective against M. javanica (EC50 = 2.60 µg/mL) than the Cu@PEG NPs (EC50 = 25 µg/mL). In contrast, the antifungal activity was approximately similar for both NPs, with EC50 values at 310 and 327 µg/mL against B. cinerea, respectively, and 260 and 278 µg/mL against S. sclerotiorum, respectively. Lettuce (Lactuca sativa) plants were inoculated with S. sclerotiorum or M. javanica and sprayed with either Cu-doped ZnO@DEG NPs or Cu@PEG NPs. The antifungal effect was evaluated based on a disease index (DI), and nematicidal activity was assessed based on the total number of galls and nematode females per root gram. NPs successfully inhibited the growth of both pathogens without causing phytotoxicity on lettuce. The DI were significantly decreased as compared to the positive control (DI = 5.2), estimated equal to 1.7, 2.9 and 2.5 for Cu@PEG NPs, Cu-doped ZnO@DEG NPs and the chemical control (KOCIDE 2000), respectively. The reduction in galling and population of M. javanica ranged from 39.32% to 32.29%, statistically like chemical control. The treatment of lettuce plants with Cu-doped ZnO@DEG NPs increased the leaf net photosynthetic value at 4.60 and 6.66 µmol CO2-2 s-1 in plants inoculated with S. sclerotiorum and M. javanica, respectively, as compared to the control (3.00 µmol CO2-2 s-1). The antioxidant capacity of NPs treated lettuce plants was evaluated as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in leaf extracts. Plants inoculated with S. sclerotiorum and sprayed with Cu-doped ZnO@DEG and Cu@PEG NPs, exhibited a 34.22% and 32.70% increase in antioxidant capacity, respectively, higher than the control. Similarly, an increase in antioxidant capacity was measured (39.49 and 37.36%) in lettuce inoculated with M. javanica and treated with Cu-doped ZnO@DEG and Cu@PEG NPs, respectively. Moreover, an increase of phenolic compounds in lettuce leaf tissue treated with NPs was measured as compared to the control. Overall, foliar applied Cu and Cu-doped ZnO NPs could be a promising tool to control phytopathogenic fungi and nematodes contributing to sustainability of agri-food sector.

Impact of Geraniol and Geraniol Nanoemulsions on Botrytis cinerea and Effect of Geraniol on Cucumber Plants' Metabolic Profile Analyzed by LC-QTOF-MS.

In the present study, the bioactive substance geraniol was tested in vitro and in planta against B. cinerea on cucumber plants, and the changes in the metabolic profile of cucumber plants inoculated with the pathogen and/or treated with geraniol were monitored by a novel LC-QTOF-MS method employing target and suspect screening. The aforementioned treatments were also studied for their impact on membrane lipid peroxidation calculated as malondialdehyde (MDA) content. Additionally, geraniol-loaded nanoemulsions (GNEs) were synthesized and tested against B. cinerea as an integrated formulation mode of geraniol application. The EC50 values calculated for geraniol and GNEs against B. cinerea were calculated at 235 µg/mL and 105 µg/mL, respectively. The in planta experiment on cucumber plants demonstrated the ability of geraniol and GNEs to significantly inhibit B. cinerea under greenhouse conditions. The LC-QTOF-MS analysis of the metabolic profile of the cucumber plants treated with geraniol demonstrated an increase in the concentration levels of myricetin, chlorogenic acid, and kaempferol rhamnoside, as compared to control plants and the presence of B. cinerea caused an increase in sinapic acid and genistein. These compounds are part of important biosynthetic pathways mostly related to responses against a pathogen attack.

ZnO NPs immobilized by Alizarin as in vitro predictive and imaging biomarkers for protein amyloidosis.

Protein amyloidosis represents the main pathological hallmark of many incurable neurodegenerative disorders and protein misfolding diseases. Nanomaterials-based approaches give rise to diagnosis and/or prediction of these proteinopathies, with regards to the multifactorial nature of their pathogenesis. Herein, crystalline truncated hexagonal shaped naked ZnO nanoparticles (mean value 47.4 nm) have been solvothermally prepared and immobilized further with alizarin (Alzn) molecules (54%) to stand up to amyloidosis acting both as inhibitors and imaging agents, as well as antioxidants. Thioflavin-T (ThT) assay revealed that the resulted zinc oxide nanoparticles immobilized with alizarin (ZnO@Alzn NPs) inhibited in vitro insulin amyloids formation in a dose-dependent manner, while the kinetic mechanism of the phenomenon was recorded. In parallel, amyloid oligomers and plaques have been visualized by conventional optical microscopy upon protein co-incubation with ZnO@Alzn NPs, highlighting the imaging ability of the immobilized NPs. The antioxidant activity was monitored by 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, through which it was shown that alizarin incorporation onto the inorganic core leads to the reduction of IC50 values from 221 µg/mL to 167 µg/mL. The enhanced free radical scavenging effects of ZnO@Alzn compared to the naked-ZnO NPs, features their prospect to serve additional functions.

Uranium and Thorium water decontamination via novel coated Cu-based nanoparticles; the role of chemistry and environmental implications.

The removal of radioactive contaminants from aquifers is a matter of great concern. In this paper, coated copper-based nanoparticles (Cu-based NPs) were investigated as sorbent materials to remove uranium and thorium from low-level wastes, and especially from water, considering the influences of temperature, time, concentration, and pH. Cu-based NPs were derived through a hydrothermal synthesis from copper nitrate degradation in the presence of the bifunctional with COOH-terminated PEG, TEG as well as PEG 8000. The characterization was undertaken using XRD, TEM, TG/DTG, FTIR, and SEM-EDS. Isotherm models such as Langmuir and Freundlich were applied, while kinetic data were successfully reproduced by the pseudo-second-order equation and thermodynamic parameters were calculated. To investigate the removal mechanisms, UV-fluorescence and X-ray photoelectron spectroscopy were used. In the case of uranium, the predominant mechanism includes the formation of surface complexes, followed by extensive reduction (65%) of U(VI) to less soluble U(IV) while in the case of thorium, surface precipitation dominates. Copper nanoparticles exhibited significant U(VI) uptake capacity resulting in a decrease of the U-concentration below the acceptable limit of 30 µg/L and can be successfully applied in water treatment technology.

Magnetic Nanocomposites of Coated Ferrites/MOF as Pesticide Adsorbents.

Magnetic metal-organic frameworks (MMOFs) are gaining increased attention as emerging adsorbents/water remediation agents. Herein, a facile development of novel MMOFs comprised of coated ferrite nanoparticles (MNPs) and UiO-66 metal-organic framework is reported. In specific, coated Co- and Zn-doped ferrite magnetic nanoparticles were synthesized as building block while the metal-organic framework was grown in the presence of MNPs via a semi-self-assembly approach. The utilization of coated MNPs facilitated the conjugation and stands as a novel strategy for fabricating MMOFs with increased stability and an explicit structure. MMOFs were isolated with 13-25 nm crystallites sizes, 244-332 m2/g specific surface area (SSA) and 22-42 emu/g saturation magnetization values. Establishing the UiO-66 framework via the reported semi-self-assembly resulted in roughly 70% reduction in both magnetic properties and SSA, compared with the initial MNPs building blocks and UiO-66 framework, respectively. Nonetheless, the remaining 30% of the magnetization and SSA was adequate for successful and sufficient adsorption of two different pesticides, 2,4-Dichlorophenoxyacetic acid (2,4-D) and 2,4,5-Trichlorophenoxyacetic acid (2,4,5-T), while the recovery with a commercial magnet and reuse were also found to be effective. Adsorption and kinetic studies for all three MMOFs and both pesticides were performed, and data were fitted to Langmuir-Freundlich isotherm models.

CuZn and ZnO Nanoflowers as Nano-Fungicides against Botrytis cinerea and Sclerotinia sclerotiorum: Phytoprotection, Translocation, and Impact after Foliar Application.

Inorganic nanoparticles (INPs) have dynamically emerged in plant protection. The uptake of INPs by plants mostly depends on the size, chemical composition, morphology, and the type of coating on their surface. Herein, hybrid ensembles of glycol-coated bimetallic CuZn and ZnO nanoparticles (NPs) have been solvothermally synthesized in the presence of DEG and PEG, physicochemically characterized, and tested as nano-fungicides. Particularly, nanoflowers (NFs) of CuZn@DEG and ZnO@PEG have been isolated with crystallite sizes 40 and 15 nm, respectively. Organic coating DEG and PEG (23% and 63%, respectively) was found to protect the NFs formation effectively. The CuZn@DEG and ZnO@PEG NFs revealed a growth inhibition of phytopathogenic fungi Botrytis cinerea and Sclerotinia sclerotiorum in a dose-dependent manner with CuZn@DEG NFs being more efficient against both fungi with EC50 values of 418 and 311 µg/mL respectively. Lettuce (Lactuca sativa) plants inoculated with S. sclerotiorum were treated with the NFs, and their antifungal effect was evaluated based on a disease index. Plants sprayed with ZnO@PEG NFs showed a relatively higher net photosynthetic (4.70 µmol CO2 m-2s-1) and quantum yield rate (0.72) than with CuZn@DEG NFs (3.00 µmol CO2 m-2s-1 and 0.68). Furthermore, the penetration of Alizarin Red S-labeled NFs in plants was investigated. The translocation from leaves to roots through the stem was evident, while ZnO@PEG NFs were mainly trapped on the leaves. In all cases, no phytotoxicity was observed in the lettuce plants after treatment with the NFs.

Magneto-fluorescent nanocomposites: experimental and theoretical linkage for the optimization of magnetic hyperthermia.

Magneto-fluorescent nanocomposites have been recognized as an emerging class of materials displaying great potential for improved magnetic hyperthermia assisted by optical imaging. In this study, we have designed a series of hybrid composites that consist of zinc doped ZnxFe3-xO4 ferrites functionalized by polyethylene-glycol (PEG8000) and an orange-emitting platinum complex [Pt(phen)Cl2]. Experimental and theoretical studies on the optimization of their magnetically-mediated heating properties were conducted. PEG was assembled around particles' surface by two different approaches; in situ and post-PEGylation. PEGylation ensured the optimal distance between the magnetic core and Pt(ii)-complex to maintain significant luminescence in the composite. The successful inclusion of the complex to the organic matrix was confirmed by a variety of spectroscopic techniques. A theoretical model was developed, based on linear response theory, in order to examine the composites' power losses dependence on their properties. Within this model, inter-particle interactions were quantified by inserting a mean dipolar energy term in the estimation of Néel relaxation time, and consequently, the size and concentration that maximize power loss were derived (20 nm and 4 mg mL-1). Moreover, a decrease in the anisotropy of nanoparticles resulted in an increase in specific loss power values. Theoretical estimations are validated by experimental data when heating aqueous dispersions of composites in 24 kA m-1, 765 kHz AMF for various values of concentration and size. Magnetic hyperthermia results showed that the theory-predicted values of optimum concentration and size delivered the maximum-specific loss power which was found equal to 545 W g-1. By the present approach, a quantitative link between the particles' dipolar interactions and their heating properties is established, while opening new perspectives to nanotheranostic applications.

Magnetic nanoemulsions as candidates for Alzheimer's disease dual imaging theranostics.

Alzheimer's disease (AD) is the most prevalent cause of dementia linked to the accumulation of amyloid-beta (Aß) plaques-fibrils that impair cognitive functions. Magnetic nanoparticles (MNPs) are emerging as promising tools for the crusade against AD owning to appropriate biocompatibility and facile functionalization that can lead to theranostic agents. Herein, the fabrication of a multimodal (magnetic resonance imaging (MRI), fluorescence imaging, and drug carrier) magnetic nanoemulsion (MNE) is reported as an AD theranostic candidate. Initially zinc ferrite MNPs of high saturation magnetization (129 emu g-1) were synthesized through a modified microwave-assisted polyol process. Memantine (a registered AD drug) was labeled with fluorescein (Mem-Flu) and encapsulated with the MNPs in sodium dodecyl sulfate micelles to form the MNE. Small hydrodynamic size (107), high encapsulation (77.5%) and loading efficiencies (86.1%) and sufficient transverse relaxivity (48.7 mM-1 s-1) were achieved through the design while sustained release of Mem-Flu was unveiled by in zero-order, first-order, Higuchi and Korsmeyer-Peppas pharmacokinetic models. Moreover, the MNE acquired fluorescence imaging ability of Aß1-42 peptide monomers and/or plaques-fibrils via the fluorescein labeling of Memantine. A novel inorganic-organic hybrid multimodal AD theranostic candidate is presented.

Toxicity assessment and comparison of the land snail's Cornu aspersum responses against CuO nanoparticles and ZnO nanoparticles.

The goal of the present study was to examine the effects of ZnO NPs and CuO NPs on Cornu aspersum land snail, enlightening their cytotoxic profile. ZnO NPs and CuO NPs were synthesized and thoroughly characterized. Α series of concentrations of either ZnO NPs or CuO NPs were administered in the feed of snails for 20 days. Thereafter, neutral red retention assay was conducted, in order to estimate NRRT50 values. Subsequently, snails were fed with NPs concentrations slightly lower than the concentrations that were corresponding to the NRRT50 values, i.e. 3 mg·L-1 ZnO NPs and 6 mg·L-1 CuO NPs, for 1, 5, 10 and 20 days. Both NPs agglomerates were detected in hemocytes by Transmission Electron Microscopy. Moreover, both effectors resulted to toxicity in the snails' hemocytes. The latter was shown by changes in the NRRT50 values, increased reactive oxygen species (ROS) production, lipid peroxidation, DNA integrity loss, protein carbonyl content, ubiquitin conjugates and cleaved caspases conjugates levels compared to the untreated animals. Although ZnO NPs exhibited higher toxicity, as indicated by the NRRT50 values, both NPs affected similarly a wide range of the cellular parameters mentioned above. The latter parameters could constitute sensitive biomarkers in biomonitoring studies of terrestrial environment against nanoparticles.

Diverse Surface Chemistry of Cobalt Ferrite Nanoparticles to Optimize Copper(II) Removal from Aqueous Media.

Water pollution by heavy metals is one of the most serious worldwide environmental issues. With a focus on copper(II) ions and copper complex removal, in the present study, ultra-small primary CoFe2O4 magnetic nanoparticles (MNPs) coated with octadecylamine (ODA) of adequate magnetization were solvothermally prepared. The surface modification of the initial MNPs was adapted via three different chemical approaches based on amine and/or carboxylate functional groups: (i) the deposition of polyethylimide (PEI), (ii) covalent binding with diethylenetriaminepentaacetic acid (DTPA), and (iii) conjugation with both PEI and DTPA, respectively. FT-IR, TGA, and DLS measurements confirmed that PEI or/and DTPA were successfully functionalized. The percentage of the free amine (-NH2) groups was also estimated. Increased magnetization values were found in case of PEI and DTPA-modified MNPs that stemmed from the adsorbed amine or oxygen ligands. Comparative UV-Vis studies for copper(II) ion removal from aqueous solutions were conducted, and the effect of time on the adsorption capacity was analyzed. The PEI-modified particles exhibited the highest adsorption capacity (164.2 mg/g) for copper(II) ions and followed the pseudo-second-order kinetics, while the polynuclear copper(II) complex Cux(DTPA)y was also able to be immobilized. The nanoadsorbents were quickly isolated from the solution by magnetic separation and regenerated easily by acidic treatment.

Interaction of ZnO Nanostructures with Proteins: In Vitro Fibrillation/Antifibrillation Studies and in Silico Molecular Docking Simulations.

Protein amyloidosis is related to many neurological disorders. Nanoparticles (NPs) due to their small size can regulate both the polypeptide monomers/oligomers assembly into amyloid fibrils/plaques and the disintegration of the existent plaques. Herein, we have synthesized ZnO nanoflowers and polyol-coated ZnO NPs of relatively small size (40 nm) with cylindrical shape, through solvothermal and microwave-assisted routes, respectively. The effect of the different morphology of nanostructures on the fibrillation/antifibrillation process was monitored in bovine serum albumin (BSA) and human insulin (HI) by fluorescence Thioflavin T (ThT) measurements. Although both nanomaterials affected the amyloid formation mechanism as well as their disaggregation, ZnO nanoflowers with their sharp edges exhibited the greatest amyloid degradation rate in both model proteins (73% and 35%, respectively) and inhibited the most the insulin fibril growth, while restrained also the fibrillation process in the case of albumin solution. In silico molecular docking simulations on the crystal structure of BSA and HI were performed to analyze further the observed in vitro activity of ZnO nanostructures. The binding energy of ZnO NPs was found lower for BSA (-5.44), highlighting their ability to act as catalysts in the fibrillation process of albumin monomers.

Structure Differentiation of Hydrophilic Brass Nanoparticles Using a Polyol Toolbox.

Nano-brasses are emerging as a new class of composition-dependent applicable materials. It remains a challenge to synthesize hydrophilic brass nanoparticles (NPs) and further exploit them for promising bio-applications. Based on red/ox potential of polyol and nitrate salts precursors, a series of hydrophilic brass formulations of different nanoarchitectures was prepared and characterized. Self-assembly synthesis was performed in the presence of triethylene glycol (TrEG) and nitrate precursors Cu(NO3)2·3H2O and Zn(NO3)2·6H2O in an autoclave system, at different temperatures, conventional or microwave-assisted heating, while a range of precursor ratios was investigated. NPs were thoroughly characterized via X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmition electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), and ζ-potential to determine the crystal structure, composition, morphology, size, state of polyol coating, and aqueous colloidal stability. Distinct bimetallic α-brasses and γ-brasses, α-Cu40Zn25/γ-Cu11Zn24, α-Cu63Zn37, α-Cu47Zn10/γ-Cu19Zn24, and hierarchical core/shell structures, α-Cu59Zn30@(ZnO)11, Cu35Zn16@(ZnO)49, α-Cu37Zn18@(ZnO)45, Cu@Zinc oxalate, were produced by each synthetic protocol as stoichiometric, copper-rich, and/or zinc-rich nanomaterials. TEM sizes were estimated at 20-40 nm for pure bimetallic particles and at 45-70 nm for hierarchical core/shell structures. Crystallite sizes for the bimetallic nanocrystals were found ca. 30-45 nm, while in the case of the core-shell structures, smaller values around 15-20 nm were calculated for the ZnO shells. Oxidation and/or fragmentation of TrEG was unveiled and attributed to the different fabrication routes and formation mechanisms. All NPs were hydrophilic with 20-30% w/w of polyol coating, non-ionic colloidal stabilization (-5 mV < ζ-potential < -13 mV) and relatively small hydrodynamic sizes (<250 nm). The polyol toolbox proved effective in tailoring the structure and composition of hydrophilic brass NPs while keeping the crystallite and hydrodynamic sizes fixed.

Leaf Age-Dependent Effects of Foliar-Sprayed CuZn Nanoparticles on Photosynthetic Efficiency and ROS Generation in Arabidopsis thaliana.

Young and mature leaves of Arabidopsis thaliana were exposed by foliar spray to 30 mg L-1 of CuZn nanoparticles (NPs). The NPs were synthesized by a microwave-assisted polyol process and characterized by dynamic light scattering (DLS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). CuZn NPs effects in Arabidopsis leaves were evaluated by chlorophyll fluorescence imaging analysis that revealed spatiotemporal heterogeneity of the quantum efficiency of PSII photochemistry (ΦPSΙΙ) and the redox state of the plastoquinone (PQ) pool (qp), measured 30 min, 90 min, 180 min, and 240 min after spraying. Photosystem II (PSII) function in young leaves was observed to be negatively influenced, especially 30 min after spraying, at which point increased H2O2 generation was correlated to the lower oxidized state of the PQ pool.. Recovery of young leaves photosynthetic efficiency appeared only after 240 min of NPs spray when also the level of ROS accumulation was similar to control leaves. On the contrary, a beneficial effect on PSII function in mature leaves after 30 min of the CuZn NPs spray was observed, with increased ΦPSΙΙ, an increased electron transport rate (ETR), decreased singlet oxygen (1O2) formation, and H2O2 production at the same level of control leaves.An explanation for this differential response is suggested.

The Effect of Polyol Composition on the Structural and Magnetic Properties of Magnetite Nanoparticles for Magnetic Particle Hyperthermia.

A study of the influence of polyols, with or without an additional reducing agent, on crystallites' size and magnetic features in Fe3O4 nanoparticles and on their performance in magnetic particle hyperthermia is presented. Three different samples were synthesized by thermal decomposition of an iron precursor in the presence of NaBH4 in a polyol. So far, triethylene glycol (TrEG) and polyethylene glycol (PEG 1000 and PEG 8000) that exhibit different physical and chemical properties have been used in order to investigate the influence of the polyols on the composition and the size of the NPs. Additionally, the presence of a different reducing agent such as hydrazine, has been tested for comparison reasons in case of TrEG. Three more samples were prepared solvothermally by using the same polyols, which led to different crystallite sizes. The magnetic core of the nanoparticles was characterized, while the presence of the surfactant was studied qualitatively and quantitatively. Concerning the magnetic features, all samples present magnetic hysteresis including remanence and coercivity revealing that they are thermally blocked at room temperature. Finally, a study on the influence of the MNPs heating efficiency from their size and the field amplitude was accomplished. In our polyol process the main idea was to control the specific loss power (SLP) values by the nanoparticles' size and consequently by the polyol itself.