Exploring the environmental and potential therapeutic applications of Myrtus communis L. assisted synthesized zinc oxide (ZnO) and iron doped zinc oxide (Fe-ZnO) nanoparticles

A sandwich-type photoelectrochemical biosensor based on anthocyanin-sensitized ZnO/P5FIn heterojunction for the sensitive detection of CYFRA21-1

. A sandwich-type photoelectrochemical (PEC) immunosensor based on a ZnO/poly(5-formylindole) (P5FIn)/anthocyanin heterostructure was developed to achieve sensitive background-free detection of the tumor marker CYFRA21-1. ZnO with good photovoltaic properties is combined with narrow bandgap P5FIn to form a p-n type heterojunction. This structure reduces the electron-hole pair recombination, thereby enhancing the photocurrent response of the composite. Anthocyanidins are environmentally friendly natural compounds with excellent antioxidant, redox properties, and remarkable electrochemical activity. After sensitization by anthocyanins, the absorption and utilization of visible light in the composites are enhanced, further improving the PEC luminescence efficiency of the materials. Additionally, boron nitride quantum dots (BN QDs) are combined with Ab2 via polydopamine (PDA) as a secondary antibody marker, enhancing its sensitivity. The biosensor exhibited a linear detection range of 0.001-100 ng mL-1 with a limit of detection (LOD) of 0.00033 ng mL-1. Furthermore, this biosensor demonstrates excellent selectivity, reproducibility, and stability, as well as successful results in analyzing actual human serum samples. This approach provides a feasible method for tumor marker detection.

Foliar-applied iron and zinc nanoparticles improved plant growth, phenolic compounds, essential oil yield, and rosmarinic acid production of lemon balm (Melissa officinalis L.)

Metallic nanoparticles (NPs) have been highlighted to improve plant growth and development in the recent years. Although positive effects of some NPs have been reported on medicinal plants, the knowledge for stimulations application of iron (Fe) and zinc (Zn) NPs is not available. Hence, the present work aimed to discover the effects of Fe NPs at 10, 20, and 30 mg L-1 and Zn NPs at 60 and 120 mg L-1 on growth, water content, photosynthesis pigments, phenolic content, essential oil (EO) quality, and rosmarinic acid (RA) production of lemon balm (Melissa officinalis L.). The results showed that Fe NPs at 20 and 30 mg L-1 and Zn NPs at 120 mg L-1 significantly improved biochemical attributes. Compared with control plants, the interaction of Fe NPs at 30 mg-1 and Zn NPs at 120 mg L-1 led to noticeable increases in shoot weight (72%), root weight (92%), chlorophyll (Chl) a (74%), Chl b (47%), RA (66%), proline (81%), glycine betaine (GB, 231%), protein (286%), relative water content (8%), EO yield (217%), total phenolic content (63%), and total flavonoid content (57%). Heat map analysis revealed that protein, GB, EO yield, shoot weight, root weight, and proline had the maximum changes upon Fe NPs. Totally, the present study recommended the stimulations application of Fe NPs at 20-30 mg L-1 and Zn NPs at 120 mg L-1 to reach the optimum growth and secondary metabolites of lemon balm.

Lepidium sativum Seed Extract-Mediated Synthesis of Zinc Oxide Nanoparticles: Structural, Morphological, Optical, Hemolysis, and Antibacterial Studies

Nanomaterials have unique physicochemical properties compared to their bulk counterparts. Besides, biologically synthesized nanoparticles (NPs) have proven superior to other methods. This work aimed to biosynthesize zinc oxide (ZnO) NPs using an aqueous extract of Lepidium sativum seed. The obtained ZnO NPs were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and ultraviolet-visible spectroscopy. The in vitro antibacterial activity of ZnO NPs against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria was assessed using the disk diffusion technique. The hemolytic impact was quantified spectrophotometrically. The results indicated a 24.2 nm crystallite size, a hexagonal structure phase, and a 3.48 eV optical bandgap. Antibacterial studies revealed a dose-dependent response with comparable activity to the standard drug (gentamicin) and higher activity against S. aureus than E. coli, e.g., the zone of inhibition at 120 mg/mL was 23 ± 1.25 and 16 ± 1.00 mm, respectively. The hemolysis assay showed no potential harm due to ZnO NPs toward red blood cells if utilized in low doses. As a result, it could be concluded that the reported biogenic method for synthesizing ZnO NPs is promising, resulting in hemocompatible NPs and comparable bactericidal agents.

Nanocomposites from spent coffee grounds and iron/zinc oxide: green synthesis, characterization, and application in textile wastewater treatment

This study reports on a novel composite of bimetallic FeO/ZnO nanoparticles supported by spent coffee grounds (SCGs). The leaves of eucalyptus (Eucalyptus globulus Labill) and trumpet (Cuphea aequipetala Cav), with their high antioxidant content, serve as bio-reductant agents for the green synthesis of nanoparticles. It was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Stable nanoparticles were produced with different diameters of 5-30 nm, and they were applied as catalysts in Fenton-like processes. Box-Behnken experimental design (BBD) was used to determine the optimal removal efficiency with three factors and was used in the degradation of textile dyes from wastewater. The nanocomposite displayed a high decolorization ratio (88%) of indigo carmine in the presence of H2O2 combined. This resulted in a reduction in chemical oxygen demand (COD) of 56% at 120 min of contact time at an initial pH of 3.0 and a 0.5 g/L of catalyst dose, a H2O2 concentration of 8.8 mM/L, an initial dye concentration of 100 mg/L, and a temperature of 25 °C.

Generation of Highly Antioxidant Submicron Particles from Myrtus communis Leaf Extract by Supercritical Antisolvent Extraction Process

Submicron particles have been produced from an ethanolic extract of Myrtus communnis leaves using supercritical carbon dioxide technology, hereinafter referred to as Supercritical Antisolvent Extraction (SAE). The influence of pressure (9-20 MPa), temperature (308 and 328 K) and injection rate (3 and 8 mL/min) on the particles' precipitation has been investigated, and it has been confirmed that increases in pressure and temperature led to smaller particle sizes. The obtained particles had a quasi-spherical shape with sizes ranging from 0.42 to 1.32 μm. Moreover, the bioactivity of the generated particles was assessed and large contents of phenolic compounds with a high antioxidant activity were measured. The particles were also subjected to in vitro studies against oxidative stress. The myrtle particles demonstrated cytoprotective properties when applied at low concentrations (1 μM) to macrophage cell lines.

An Evaluation of the Biocatalyst for the Synthesis and Application of Zinc Oxide Nanoparticles for Water Remediation—A Review

Global water scarcity is threatening the lives of humans, and it is exacerbated by the contamination of water, which occurs because of increased industrialization and soaring population density. The available conventional physical and chemical water treatment techniques are hazardous to living organisms and are not environmentally friendly, as toxic chemical elements are used during these processes. Nanotechnology has presented a possible way in which to solve these issues by using unique materials with desirable properties. Zinc oxide nanoparticles (ZnO NPs) can be used effectively and efficiently for water treatment, along with other nanotechnologies. Owing to rising concerns regarding the environmental unfriendliness and toxicity of nanomaterials, ZnO NPs have recently been synthesized through biologically available and replenishable sources using a green chemistry or green synthesis protocol. The green-synthesized ZnO NPs are less toxic, more eco-friendly, and more biocompatible than other chemically and physically synthesized materials. In this article, the biogenic synthesis and characterization techniques of ZnO NPs using plants, bacteria, fungi, algae, and biological derivatives are reviewed and discussed. The applications of the biologically prepared ZnO NPs, when used for water treatment, are outlined. Additionally, their mechanisms of action, such as the photocatalytic degradation of dyes, the production of reactive oxygen species (ROS), the generation of compounds such as hydrogen peroxide and superoxide, Zn2+ release to degrade microbes, as well as their adsorbent properties with regard to heavy metals and other contaminants in water bodies, are explained. Furthermore, challenges facing the green synthesis of these nanomaterials are outlined. Future research should focus on how nanomaterials should reach the commercialization stage, and suggestions as to how this ought to be achieved are presented.

Facile Green Synthesis of Zinc Oxide Nanoparticles with Potential Synergistic Activity with Common Antifungal Agents against Multidrug-Resistant Candidal Strains

The high incidence of fungal resistance to antifungal drugs represents a global concern, contributing to high levels of morbidity and mortality, especially among immunocompromised patients. Moreover, conventional antifungal medications have poor therapeutic outcomes, as well as possible toxicities resulting from long-term administration. Accordingly, the aim of the present study was to investigate the antifungal effectiveness of biogenic zinc oxide nanoparticles (ZnO NPs) against multidrug-resistant candidal strains. Biogenic ZnO NPs were characterized using physicochemical methods, such as UV-vis spectroscopy, transmission electron microscopy (TEM), energy-dispersive X ray (EDX) spectroscopy, FTIR (Fourier transform infrared) spectroscopy and X-ray powder diffraction (XRD) analysis. UV spectral analysis revealed the formation of two absorption peaks at 367 and 506 nm, which preliminarily indicated the successful synthesis of ZnO NPs, whereas TEM analysis showed that ZnO NPs exhibited an average particle size of 22.84 nm. The EDX spectrum confirmed the successful synthesis of ZnO nanoparticles free of impurities. The FTIR spectrum of the biosynthesized ZnO NPs showed different absorption peaks at 3427.99, 1707.86, 1621.50, 1424.16, 1325.22, 1224.67, 1178.22, 1067.69, 861.22, 752.97 and 574.11 cm−1, corresponding to various functional groups. The average zeta potential value of the ZnO NPs was −7.45 mV. XRD analysis revealed the presence of six diffraction peaks at 2θ = 31.94, 34.66, 36.42, 56.42, 69.54 and 76.94°. The biogenic ZnO NPs (100µg/disk) exhibited potent antifungal activity against C. albicans, C. glabrata and C. tropicalis strains, with suppressive zone diameters of 24.18 ± 0.32, 20.17 ± 0.56 and 26.35 ± 0.16 mm, respectively. The minimal inhibitory concentration (MIC) of ZnO NPs against C. tropicalis strain was found to be 10 μg/mL, whereas the minimal fungicidal concentration (MFC) was found to be 20 μg/mL. Moreover, ZnO NPs revealed a potential synergistic efficiency with fluconazole, nystatin and clotrimazole antifungal drugs against C. albicans strain, whereas terbinafine, nystatin and itraconazole antifungal drugs showed a potential synergism with ZnO NPs against C. glabrata as a multidrug-resistant strain. In conclusion, pomegranate peel extract mediated green synthesis of ZnO NPs with potential physicochemical features and antimicrobial activity. The biosynthesized ZnO NPs could be utilized for formulation of novel drug combinations to boost the antifungal efficiency of commonly used antifungal agents.

UV-light-driven cadmium sulphide (CdS) nanocatalysts: synthesis, characterization, therapeutic and environmental applications; kinetics and thermodynamic study of photocatalytic degradation of Eosin B and Methyl Green dyes

Cadmium sulphide (CdS) nanoparticles (NPs) were synthesized through hydrothermal route and characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), Energy dispersive X-ray analysis, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and Thermo gravimetric analysis (TGA).The band gap of CdS nanoparticles was found to be 2.38 eV. CdS NPs are crystalline aggregates with hexagonal structure as shown by SEM and XRD analysis. TGA study revealed that the synthesized nanomaterials were very stable to temperature and only 6.54% total loss occurred during heating range (25 °C-600 °C).The CdS NPs were used for the first time against the degradation of Eosin B (EB) and Methyl green (MG) dyes in aqueous solution.The degradation of EB and MG over CdS nanocatalysts followed second order kinetics. The predicted activation energies for both the dyes' reactions were 61.1 kJ/mol and 32.11 kJ/mol, respectively. About 95% and 90% dye degradation was observed at the time interval of 160 minutes for EB and MG, respectively. High percent degradation of EB was observed at high pH (pH 0) while at low pH (pH 4) high percent degradation was found for MG dye. Maximum dye degradation was found at the optimal dose (0.03 g/L) of the catalyst and at low dye concentration. The rate of EB and MG dye degradation was found to increase with increase in temperature up to 45 °C. The recyclability study showed that CdS nanoparticles could be reused for the degradation of the given dyes. Good antibacterial activity against Staphylococcus aureus was shown by CdS NPs. From the biocompatibility it was confirmed that CdS NPS are bioincompatible compatible.

Olive mill wastewater phytoremediation employing economically important woody plants

In this study two plant species, Punica granatum L. and Myrtus communis L., have been tested as candidates for phytoremediation of olive mill wastewater (OMW) through recirculation in soil pilot units, according to the proposed patented technology by Santori and Cicalini [EP1216963 A. 26 Jun 2002]. Wastewater was treated in batches of low to high organics strength (COD: 2 700-45 700 mg/L) during summer months of two consecutive years. Dynamics of the most important wastewater parameters were investigated, and corresponding removal rates were estimated. During treatment of low organic load OMW, average removal rate of organics, phenolics, total nitrogen and total phosphorus were 0.68 g-COD/kg-soil d, 0.073 g-TPh/kg-soil d, 0.033 g-TN/kg-soil d and 0.0074 g-TP/kg-soil d respectively and plants proved to be tolerant to the OMW. During treatment of high organic load OMW removal rates were roughly 10-fold higher although phytotoxic symptoms were observed. Plants were found to contribute greatly to the OMW treatment process since organics removal rates in pilot units were found to be at least 10-fold higher than in wastewater treatment in non-vegetated soil. Plant species with high added value products such as pomegranate and myrtle trees were used in this study, improving the circular economy potential of the aforementioned technology. Moreover, its efficiency has been demonstrated by quantification of the overall removal rates of key constituents as well as the contribution of the plants in the OMW treatment.

Electrochemical Reduction of CO2: A Review of Cobalt Based Catalysts for Carbon Dioxide Conversion to Fuels

Electrochemical CO2 reduction reaction (CO2RR) provides a promising approach to curbing harmful emissions contributing to global warming. However, several challenges hinder the commercialization of this technology, including high overpotentials, electrode instability, and low Faradic efficiencies of desirable products. Several materials have been developed to overcome these challenges. This mini-review discusses the recent performance of various cobalt (Co) electrocatalysts, including Co-single atom, Co-multi metals, Co-complexes, Co-based metal-organic frameworks (MOFs), Co-based covalent organic frameworks (COFs), Co-nitrides, and Co-oxides. These materials are reviewed with respect to their stability of facilitating CO2 conversion to valuable products, and a summary of the current literature is highlighted, along with future perspectives for the development of efficient CO2RR.