Antioxidant, antimicrobial, and photocatalytic activity of green synthesized ZnO-NPs from Myrica esculenta fruits extract

Green synthesis of ultrafine zinc oxide nanoparticles for photocatalytic degradation of methylene blue dye: Optimization and kinetic studies

Eco-friendly preparation of zinc oxide nanoparticles using Tabernaemontana divaricata and its photocatalytic and antimicrobial activity

Zinc oxide Nanoparticles, Biosynthesis, characterization and their potent photocatalytic degradation, and antioxidant activities

Facile green synthesis of zinc oxide nanoparticles by Eucalyptus globulus and their photocatalytic and antioxidant activity

To increase the profitability and sustainability of agricultural waste, a facile green approach was established to synthesize zinc oxide nanoparticles (ZnO NPs) using saffron leaf extract as a reducing and stabilizing agent. Structural characteristics of NPs were investigated by X‐ray diffraction (XRD), Fourier‐transform infrared (FTIR), field emission scanning electron microscopy (FESEM), and UV–Visible (UV–Vis) spectroscopy. Characterization results revealed that ZnO NPs is highly crystalline with a hexagonal wurtzite structure and spherical particles with diameter less than 50 nm, as confirmed by XRD and FESEM techniques. UV–Vis absorption spectra depicted an absorption peak at 370 nm, which confirms the formation of ZnO NPs. FTIR spectral analysis confirmed the presence of functional groups and metal oxygen groups. The biological activities of ZnO NPs were also investigated. The antibacterial effect of ZnO NPs was investigated against selected food pathogens (Salmonella Typhimurium, Listeria monocytogenes, and Enterococcus faecalis). The study results prove that the green synthesized ZnO NPs show enhanced antibacterial activity against S. Typhimurium when compared with other strains. A dose‐dependent free radical scavenging activity was observed for ZnO NPs in both 2,2‐diphenyl‐1‐picryl‐hydrazyl‐hydrate (DPPH) and fluorescence recovery after photobleaching (FRAP) assays. The ZnO NPs were evaluated for their photocatalytic activity during the degradation of methylene blue (MB) dye in aqueous solutions. The maximum removal of MB achieved was 64% with an initial ZnO NP concentration of 12 mg/mL under UV light. The present study revealed that the agricultural waste (saffron leaf) provides a simple and eco‐friendly option to sustainably synthesize ZnO NPs for use as a photocatalyst. In addition, this is the first report on saffron leaf‐mediated synthesis of ZnO NPs.

Zinc oxide nanoparticles (ZnO-NPs) have been extensively researched for their potential applications in various fields such as pharmaceuticals, cosmetics, biotechnology, sensing, photocatalysis, and photovoltaics due to their unique nanoscale properties. However, the conventional methods for producing ZnO NPs require the use of hazardous chemicals and high energy consumption, which imposes certain limitations. In contrast, the green synthesis of ZnO-NPs using plant extracts, especially Origanum majorana, has gained much attention as a promising alternative approach. Plant extracts contain phytochemicals that are biologically safe and non-toxic, making them a preferred choice. In addition, the ZnO-NPs synthesized with O. majorana extracts exhibit higher stability and can be customized in terms of shape and size, unlike the ZnO-NPs obtained by bacterial or fungal methods. The aqueous leaf extract of O. majorana contains flavonoids, tannins, and phenolic derivatives, which serve as reducing and capping agents for the biosynthesis of ZnO-NPs. These extracts also contain functional groups such as -OH and -C=O, which further enhance the physicochemical properties of the resulting ZnO-NPs and influence their ability to target specific molecules. The plant-mediated synthesis of ZnO-NPs using O. majorana leaf extract is not only fast and straightforward but also offers a wide range of functionalized nanoparticles with specific morphologies and sizes. These ZnO-NPs prepared with O. majorana have been shown to have potential applications in various fields, including antimicrobial, antioxidant, and anticancer activities. This review focuses specifically on the antimicrobial applications of ZnO-NPs synthesized using O. majorana leaf extract.

Background:The Zinc oxide Nanoparticles (ZnO NPs) were synthesized successfully by using Tagetes erecta flower aqueous extract and evaluated for their antioxidant potential, antimicrobial and cytotoxic potential.Methods:Phytochemical screening of aqueous crude extract and synthesized ZnO NPs of Tagetes erecta flower revealed the presence of alkaloids, flavonoids, carbohydrates, amino acids, tannins, proteins, etc. The characterization was done by various spectral analyses. In vitro antioxidant activities of synthesized ZnO NPs were found to possess concentration-dependent free radical scavenging activity was carried on different free radicals i.e. DPPH and ABTS. Antimicrobial activity of synthesized ZnO NPs was performed by agar well diffusion method and compared with control ampicillin, while cytotoxic effects were determined by MTT assay against human cervical cancer cell line.Results:UV-Visible spectra were conducted to confirm the synthesis of ZnO NPs and peak obtained at 364.15nm. X-ray analysis confirmed the crystalline nature of the nanoparticles and the average size of the nanoparticles was 30-50nm and was spherical shape analyzed by SEM. The synthesized ZnO NPs showed antimicrobial activity against all tested microorganisms and a maximum inhibition zone was found against E. coli in gram-negative and S. aureus in gram-positive bacteria. Synthesized ZnO NPs were showed 50% cell viability at 26.53μg/ml against the HeLa cancer cell line.Conclusion:The conclusion of this study suggests both the aqueous crude extract of Tagetes erecta flower and synthesized ZnO NPs showed an excellent alternative source of antimicrobial agent also an attractive selective cytotoxic activity against HeLa tested cancer lines, offering satisfying ‘safe and cheaper’ alternatives to conventional therapy protocols.

The rapid emergence of multidrug‐resistant (MDR) pathogens, particularly in hospital wastewater, poses a serious threat to public health and emphasizes the need for alternative antimicrobial strategies. In this study, Enterococcus hirae, an environmentally derived strain, was used for the first time in the extracellular green synthesis of zinc oxide nanoparticles (ZnO NPs) and copper oxide/zinc oxide nanoparticles (CuO/ZnO NPs). The nanoparticles were characterized using standard techniques. Ultraviolet–visible (UV‐Vis) spectra, X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), and energy‐dispersive X‐ray spectroscopy (EDS) confirmed both nanoparticle formation, size, and morphology. Antimicrobial activity against Staphylococcus aureus (ATCC 6538), Morganella morganii, Kerstersia gyiorum, and Klebsiella pneumoniae was evaluated using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays, showing a 62.5% greater efficacy of bimetallic NPs than ZnO alone. The 2,2‐diphenyl‐1‐picrylhydrazyl hydrate (DPPH) assay revealed that E‐CuO/ZnO NPs exhibited superior antioxidant activity with the lowest IC50 of 5.528 μg/mL, outperforming E‐ZnO NPs, which is attributed to the synergistic effect between ZnO and CuO NPs. The combination of E‐ZnO and E‐CuO/ZnO nanoparticles with ciprofloxacin (CIP) and ceftazidime (CAZ) was evaluated against MDR isolates. Synergistic interactions were observed particularly against K. pneumoniae. This study confirms effective E. hirae‐mediated synthesis and the enhanced antibacterial and antioxidant potential of CuO/ZnO NPs, supporting eco‐friendly strategies against MDR infections, with synergistic interactions observed with conventional antibiotics, particularly against K. pneumoniae, indicating that the nanoparticles can enhance antibiotic efficacy.

Vernonia amygdalina belongs to the family Asteraceae. Its leaf extract has been used ethnobotanically in the treatment of gastrointestinal disorders, malaria, diabetes mellitus, and hiccups. This study aimed to synthesize zinc oxide nanoparticles using Vernonia amygdalina leaf extract and evaluate their antioxidant, photocatalytic, and antibacterial activities. The synthesized zinc oxide nanoparticles were characterized using UV-Vis spectroscopy, dynamic light scattering, Fourier transform infrared spectroscopy, X-ray diffraction, energydispersive X-ray analysis, and scanning electron microscopy. The photocatalytic activity was evaluated through the degradation of methylene blue dye. At the same time, the antimicrobial properties of Vernonia amygdalina leaf extract and zinc oxide nanoparticles were assessed using the minimum inhibitory concentration assay. Antioxidant activity was determined by measuring the inhibition of 2,2- diphenylpicrylhydrazyl radicals, with ascorbic acid serving as the positive control. The successful synthesis of zinc oxide nanoparticles was confirmed by a UV-Vis absorption peak at 390 nm. The nanoparticles exhibited a smooth, spherical morphology with an average size of 78.25 nm. Fourier transform infrared spectroscopy identified key functional groups responsible for nanoparticle stabilization. X-ray diffraction analysis revealed three characteristic peaks at 2θ angles of 24°, 27°, and 34°, which confirmed the crystalline nature of the synthesized zinc oxide nanoparticles. The antioxidant assay demonstrated that zinc oxide nanoparticles had a significantly higher free radical scavenging effect than Vernonia amygdalina leaf extract (P < 0.05). Energy-dispersive X-ray analysis confirmed the elemental composition of the synthesized zinc oxide nanoparticles, with 44.4% oxygen and 55.6% zinc. The photocatalytic study demonstrated that the synthesized zinc oxide nanoparticles achieved a 75% degradation rate of methylene blue dye after 120 minutes of UV light exposure. Antimicrobial testing revealed mean inhibition zones of 7.88 mm and 6.30 mm for the synthesized zinc oxide nanoparticles and Vernonia amygdalina leaf extract, respectively, indicating significant antibacterial activity against both Gram-positive and Gram-negative bacteria (P < 0.05). The 2,2-diphenylpicrylhydrazyl scavenging effects of Vernonia amygdalina leaf extract and the synthesized zinc oxide nanoparticles were also statistically significant when compared to ascorbic acid (P < 0.05). The biosynthesized Vernonia amygdalina-derived zinc oxide nanoparticles exhibited remarkable photocatalytic, antibacterial, and antioxidant properties.

Green synthesis, characterization and antimicrobial activities of zinc oxide nanoparticles from the leaf extract of Azadirachta indica (L.)

The photodegradation of organic pollutants using metal oxide-based catalysts has drawn great attention as an effective method for wastewater treatment. In this study, zinc oxide nanoparticles (ZnO NPs) and zinc oxide/copper oxide nanocomposites (ZnO/CuO NCs) were fabricated using the leaf extract of Croton macrostachyus as a nontoxic, natural reducing and stabilizing agent. The synthesized samples were characterized by employing X-ray diffraction, microscopic, spectroscopic, and electrochemical methods. The results confirmed the successful synthesis of ZnO NPs and ZnO/CuO NCs with well-defined crystalline structures and morphologies. The prepared samples were tested for the photodegradation of methylene blue (MB) dye under visible light irradiation. Compared to ZnO NPs, ZnO/CuO NCs showed greatly improved photocatalytic performances, particularly with the sample prepared with the 20 mol % Cu precursor (97.02%). The enhancement could be related to the formed p-n heterojunction, which can suppress the recombination of charge carriers and extend the photoresponsive range. A theoretical study of the photocatalytic activity of ZnO/CuO NCs against MB dye degradation was also conducted by using COMSOL Multiphysics software. The results of the simulation are in reasonable agreement with those of the experiment. This study contributes to the development of sustainable and effective photocatalytic materials that are suitable for application in environmental remediation, particularly in the treatment of wastewater.

The present study focuses on the green synthesis of zinc oxide nanoparticles (ZnO NPs) using a novel Lepidagathis ananthapuramensis (LA) leaf extract and a systematic study on the photocatalytic degradation of methylene blue (MB) dye. The structural, thermal, morphological, optical, and surface area analysis of prepared ZnO NPs were examined using X-ray diffraction (XRD), UV-visible spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, thermogravimetric analysis (TGA), field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray analysis (EDAX) and high-resolution transmission electron microscopy (HR-TEM). The LA stabilised ZnO NPs produced NPs with diverse morphologies, low band gap and cost-effective high yield of production. A systematic study has been carried out to determine the crystallinity and crystallite size of ZnO NPs based on the concentration of Zn(NO3)2 precursor, concentration of LA leaf extract, calcination temperature and calcination time. The crystallinity and crystallite size of ZnO NPs were evaluated based on the XRD technique. The photocatalytic activity of ZnO NPs was thoroughly investigated for the degradation of MB dye based on various physicochemical parameters such as reaction time, concentration of catalyst, concentration of precursors, concentration of LA extract, concentration of MB, calcination temperature and calcination time. These systematic photocatalytic studies followed green protocols and provided an excellent photocatalytic efficiency result of 96-98.5% towards the decomposition of MB. Hence, this material can work as a potential candidate for waste water treatment by also degrading other toxic dyes.

Photocatalytic activity and anti-microbial application of synthesized Zinc oxide nanoparticles (ZnO Nps) towards remediation of hospital waste water (HWW)

The fabrication of zinc oxide nanoparticles is a concept since zinc oxide nanoparticles can effectively cling onto things that it reacts to light and zinc oxide nanoparticles do not pose any threat to the environment. This paper prepared zinc oxide nanoparticles through a technique known as controlled precipitation and ultimately we monitored the appearance of zinc oxide nanoparticles as well as the process through which zinc oxide nanoparticles were prepared. We then cleaned the water with the use of these zinc oxide nanoparticles with a particular aim of eliminating metals, such as lead, cadmium and chromium. ZnO is very reactive and it has a surface area. This implies that ZnO is able to capture the metals and degrade them thereby decreasing the metal ions in the water. This informs us that ZnO nanoparticles may be a viable approach towards cleaning heavy metals in factory wastewater. This will ensure that it is safer to the environment. Some of the resources can be recovered. ZnO nanoparticles are a water cleaning material and heavy metal recovery material. ZnO nanoparticles are able to clean the water and render it safer. At this, ZnO nanoparticles are truly good. In this paper, the researcher examines how Zinc Oxide Nanoparticles can be prepared e.g. through chemical precipitation, sol-gel and green synthesis. It identifies the good and bad things regarding each of these approaches to the production of Zinc Oxide Nanoparticles. Another aspect that the paper discusses is the application of Zinc Oxide Nanoparticles in water treatment. As an example, Zinc Oxide Nanoparticles have the ability to pick pollutants. It is possible to disperse them with light and filter them. We also talk of getting metals back using Zinc Oxide Nanoparticles. Some techniques such as adsorption-desorption and electrochemical recovery can be applied to the Zinc Oxide Nanoparticles to retrieve the metals back. ZnO NPs are a good method of treating water and recovering heavy metals. ZnO NPs are quite effective in the treatment of water. Removing the heavy metals since they possess some good qualities. The paper discusses the latest development of ZnO NPs such as how to make them easily, eco-friendly, and how ZnO NPs are used to trap harmful compounds in the water using sunshine to dissipate them and using ZnO NPs to filter the water by using ZnO NPs. ZnO NPs prove to be great in the elimination of metals. We can also apply such techniques as adsorption-desorption or electrochemical recovery to recover metals using ZnO NPs. ZnO NPs is a cheap method of purifying water and recover heavy metals. The most pleasant thing is the fact that the ZnO NPs can be utilized on a scale without damaging the environment. ZnO NPs are a cleaning and retrieving heavy metals back solution to water using ZnO NPs. KEY WORDS: Cardamom, Aloe vera, Zinc nitrate hexahydrate, wastewater treatment, lead, UV visible spectroscopy, FTIR, XRD, SEM / TEM.

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 (100 µg/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.