Green Synthesis of Zinc Oxide Nanoparticles by Bacillus subtilis and their Use in Various Applications

Synthesis of nanoparticles through environmentally friendly and biologically mediated routes is the study upon which lot of research attention has been focused in recent times. In the present investigation, fungal-mediated synthesis of zinc oxide nanoparticles was explored using an economical and nature friendly approach. Synthesis of the extracellular zinc oxide nanoparticles was achieved using fungal cultures of Pleurotus, Lentinus and Agaricus spp. The synthesized nanomaterial was thoroughly characterized using physical techniques including UV-Vis Spectroscopy, SEM, XRD, and FTIR. UV-Vis Spectroscopy exposed a distinct absorption peak in the range of 300-400nm, validating the formation of nanoparticles. SEM images revealed the ZnNPs being agglomerated and irregular in shape. The size of the particles is in the average range of 10-100nm. XRD analysis demonstrated the nature of the nanoparticles as crystalline, with prominent diffraction peaks corresponding to the face-centered cubic (fcc) crystal structure of zinc oxide. FTIR analysis provided insights into the functional groups present on the nanoparticle surface. This suggests that there is some involvement of fungal biomolecules in the reduction and stabilization of zinc oxide nanoparticles. The presence of zinc oxide nanoparticles was confirmed by Energy Dispersive X-ray Analysis. Furthermore, the synthesized nanoparticles were assessed for their potential antifungal activity against Alternaria mali, a notorious phytopathogen responsible for causing leaf spot in Apple plant. The antifungal activity was assessed through poison food technique and results indicated a significant inhibition of Alternaria growth by the zinc oxide nanoparticles particularly the ones synthesized from Pleurotus, with a dose-dependent response. The mycogenic synthesis of zinc oxide nanoparticles is an eco-friendly and sustainable approach, minimizing the need for hazardous chemicals and reducing environmental impact. This study showcases the potential of zinc oxide nanoparticles as a novel and effective biofungicide against Alternaria mali and contributes to the growing body of knowledge on sustainable methods of nanoparticle synthesis and their applications in agriculture (disease management) and environmental management.

Ultrasound irradiation based in-situ synthesis of star-like Tragacanth gum/zinc oxide nanoparticles on cotton fabric

This study demonstrates the green synthesis, characterization, and biomedical applications of zinc oxide nanoparticles (ZnONPs) using Zingiber officinale (Z. officinale) (ginger) peel extract. Green synthesis offers advantages over conventional methods, including environmental friendliness, cost-effectiveness, and enhanced biocompatibility. Ultraviolet-Visible (UV-Vis) spectroscopy confirmed ZnONPs formation with a peak at 364 nm. Fourier-Transform Infrared (FTIR) spectroscopy analysis revealed characteristic peaks indicating functional groups involved in nanoparticle formation. Scanning Electron Microscope (SEM) analysis showed spherical/agglomerated nanoparticles, and Energy-Dispersive X-ray Spectroscopy (EDS) confirmed 77.7% zinc oxide by mass%. The X-ray Diffraction (XRD) indicated an average particle size of 24.67 nm with distinct crystal orientations. Phytochemical analysis detected alkaloids, saponins, and steroids in the extract. Optimal synthesis occurred at 50–60°C and pH 10, yielding stable ZnONPs. The ZnONPs exhibited significant antibacterial activity against Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Bacillus cereus (B. cereus), Escherichia coli (E.coli), Zymomonas mobilis (Z. mobilis), and Pseudomonas aeruginosa (P. aeruginosa), as well as antifungal activity against Candida albicans (C. albicans). The in vitro cytotoxicity study on M.D. Anderson – Metastatic Breast – 231 (MDA-MB-231) breast cancer cells showed a dose-dependent reduction in cell viability [Half-maximal Inhibitory Concentration (IC50) = 82.13 µg/mL] with notable morphological changes at higher concentrations. The ZnONPs synthesized from ginger peel extract are innovative, environmentally friendly, and economical. Our findings show that biologically generated ZnONPs are effective antibacterial and antifungal agents against several pathogens. This research uniquely demonstrates the potential of ginger peel, a commonly discarded agro-waste, as a sustainable source for ZnONPs synthesis, highlighting its biotechnological and medicinal applications. The novelty of this study lies in the green synthesis approach using ginger peel and the comprehensive evaluation of its antimicrobial and anticancer properties. Further in-depth studies and optimization are needed to validate their therapeutic efficacy and safety.

Using natural processes as inspiration, the present study demonstrates a positive correlation between zinc metal tolerance ability of a soil fungus and its potential for the synthesis of zinc oxide (ZnO) nanoparticles. A total of 19 fungal cultures were isolated from the rhizospheric soils of plants naturally growing at a zinc mine area in India and identified on the genus, respectively the species level. Aspergillus aeneus isolate NJP12 has been shown to have a high zinc metal tolerance ability and a potential for extracellular synthesis of ZnO nanoparticles under ambient conditions. UV-visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, and energy dispersive spectroscopy studies further confirmed the crystallinity, morphology, and composition of synthesized ZnO nanoparticles. The results revealed the synthesis of spherical nanoparticles coated with protein molecules which served as stabilizing agents. Investigations on the role of fungal extracellular proteins in the synthesis of nanoparticles indicated that the process is nonenzymatic but involves amino acids present in the protein chains.

The present work has reported a green chemistry-based approach for the synthesis of crystalline metal oxide nanoparticle using plant extract to reduce metal ions. It demonstrated the efficient synthesis of Zinc oxide nanoparticles (ZnO NPs) using aqueous leaf extract of Thryallis glauca (Cav.) Kuntze with a focus on minimizing toxic reactants and byproducts. The physicochemical characterizations by standard methods and the mechanism of action were presented. The UV-Vis absorption peak of the annealed ZnO NPs appeared at a 359 nm wavelength. The calculated direct band-gap energy was 3.6eV. The peak at 567 nm in the visible region in the photoluminescence spectra indicated surface defects from oxygen vacancy, and the vibrational peak also indicated it at 582 cm-1 in Raman spectra. FTIR spectroscopy showed the possible involvement of proteins, aromatic compounds, and alcohols as reducing agents in the reaction. X-ray diffraction analysis revealed that pure crystalline ZnO NPs have structural properties as hexagonal wurtzite below 50 nm size. Antioxidant analysis by DPPH assay illustrated an excellent free radical scavenging activity. The prepared ZnO NPs tested against pathogenic Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis did not show any antibacterial activity. HIGHLIGHTS: Renewable, eco-friendly plant material was used to synthesize Zinc Oxide nanoparticles (NPs). Synthesis of thermally stable, pure crystalline NPs with good optical properties. The synthesized NPs showed excellent free radical scavenging activity. ZnO NPs exhibited antibacterial resistance at the test concentrations.

An overview of recent work on the low-temperature plasma-assisted synthesis of zinc oxide (ZnO) nanoparticles is presented and interpreted in terms of gas-phase and surface reactions with illustrated examples. The thermodynamical nonequilibrium conditions allow the formation of chemically reactive species with a potential energy of several eV, which readily interact with the Zn precursors and initiate reactions leading to the formation of nanoparticles or nanowires. The high-quality nanowires were synthesized from Zn powders only upon interaction with moderately ionized plasma in a narrow range of plasma parameters. This technique is promising for the synthesis of large quantities of nanowires with aspect ratios well above 10, but the exact range of parameters remains to be determined. Apart from the ex situ techniques, the ZnO nanoparticles can be synthesized by depositing a film of precursors (often Zn salts or Zn-containing organometallic compounds) and exposing them to oxygen plasma. This technique is useful for the synthesis of well-adherent ZnO nanoparticles on heat-sensitive objects but requires further scientific validation as it often leads to the formation of a semicontinuous ZnO film rather than nanoparticles. Both low-pressure and atmospheric plasmas are useful in converting the precursor film into ZnO nanoparticles despite completely different mechanisms.

The application of green methods in the synthesis of nanoparticles using plants is a cost-effective and eco-friendly approach. Zinc oxide nanoparticles are of great importance due to their versatile properties. The conditions of synthesis strongly influence the characteristics and functionality of the nanoparticles. The present work studied the biological, green synthesis of zinc oxide nanoparticles (ZnONPs) in the presence of different concentrations of ethanolic extract of Larrea tridentata (10, 20, and 30 mg/mL). The time of the formation of nanoparticles was evaluated at different temperatures and pH values of the reaction medium. The formation of ZnONPs was confirmed by ultraviolet-visible (UV-Vis) and Fourier transform infrared spectroscopies (FT-IR), as well as scanning electron microscopy (SEM). X-ray diffraction analysis (XDR) determined the crystallographic structure of the nanoparticles. Obtained ZnONPs had a size range of 18 to 40 nm. The temperature, reaction time, and pH significantly influenced the nanoparticles’ morphology, size, and aggregation. The impact of chosen ZnONPs was tested on the germination of serrano chili seeds (Capsicum annuum). At 100 ppm, the nanoparticles improved germination percentage, vigor, and seedlings’ growth parameters.

Synthesis of nanoparticles with a green approach using plants has attracted great attention from scientific communities because of its characteristics, such as environmentally friendly and time-efficient. In this study, green synthesis of zinc oxide nanoparticles was performed by Citrus aurantium aqueous peel extract. UV–VIS, FTIR, zeta potential, SEM, and EDX were used in characterization studies. In the UV–Vis spectrum, a heightening of the absorbance was monitored in the range of 260–390 nm specific to ZnO. The mean particle size of zinc oxide NPs (ZnONPs) was characterized as 632 ± 41 nm with low polydispersity (0.174 ± 0.055). As a result of EDX analysis, the presence of Zn in the scanned area was determined as 2.32%. The cytotoxic behaviors of ZnONPs on human breast cancer cells (MDA-MB-231) were carried out by MTT method. It was discovered that after ZnONPs application, cell migration decreased and apoptotic cell rate increased with Hoescht/PI staining in MDA-MB-231 cells.

Green synthesis of zinc oxide (ZnO) nanoparticles (NPs) using various plant extracts as reducing and capping agents has gained attention in recent research. The green synthesis of ZnO NPs offers several advantages such as being simple, eco-friendly, safe, cost-effective, and reproducible approach with high stability. Hence, this article provides an overview of zinc metal and ZnO compounds, and traditional chemical and physical synthesis of ZnO NPs with primary focuses on the green synthesis of ZnO NPs. This study discusses various plant extracts used and the proposed mechanisms in the green synthesis of ZnO NPs. Additionally, it explores the cytotoxic mechanisms of the green-synthesized ZnO NPs and addresses the various biomedical applications of ZnO NPs, including antibacterial, anticancer, antidiabetic, antioxidant, antifungal, antiviral, antiparasitic, anti-inflammatory, and wound healing. Moreover, the review critically discusses the toxicity of ZnO NPs and emphasizes the need for more toxicological studies to ensure the safety and facilitate the risk assessments and risk management of ZnO NPs. Furthermore, this review underlines the challenges associated with the translation process of ZnO NPs from bench to market, including the complex and time-consuming regulatory approval process for ZnO NPs, which requires a multidisciplinary approach involving scientists, regulators, and manufacturers.

Synthesis of ZnO nanoparticles from zinc acetate dihydrate – An environmental friendly technique

Biosynthesis and characterization of phyto mediated zinc oxide nanoparticles: A green chemistry approach

The green synthesis of zinc oxide nanoparticles from plant extract is attracting great interest owing to the cost effectiveness and ecofriendly method of synthesis. Crystalline hexagonal shape zinc oxide (ZnO) nanoparticles of approximately 50-100 nm were synthesized through a one-step solution-based technique using alcohol free Artemisia pallens plant extract as a reducing agent. Analysis of the synthesized nanoparticles using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) exhibited homogenous wurtzite structure. TEM and selected area electron diffraction studies showed the zinc oxide nanoparticles are crystalline and hexagonal with growth direction in (101) plane. Fourier transform infrared spectrum showed a single band at 478.34 cm−1 which can be attributed to Zn-O vibrational band. The composition of the synthesized ZnO nanoparticles was then confirmed through energy dispersive X-ray spectroscopy results. In this work, the antimicrobial activity of ZnO nanoparticles was studied. The development of synthesizing metal nanoparticles (MNPs) by plant extracts has become a major focus of research as these nanoparticles have low environmental hazards and low human toxicity. This makes it a commonly used source of nanoparticle synthesis with an efficient, extremely eclectic, relatively cheap and traditional agent that has been used for many years to successfully prepare different organic molecules and compounds.

This study provides evidence for the green synthesis of zinc oxide nanoparticles (ZnO NPs) using Vitex negundo leaf extract. The UV–Visible (UV–Vis) spectrum of ZnO NPs and calcinated ZnO NPs (ZnO-C) showed peaks at 370[Formula: see text]nm and 374[Formula: see text]nm, respectively, confirming zinc ion reduction to zinc oxide. The ZnO NPs and calcinated counterparts were further characterized by FTIR, XRD, FE-SEM and EDX. FTIR results revealed the presence of alcoholic and aromatic groups, like flavonoids, in the leaf extract. The XRD pattern showed a distinctive Wurtzite crystalline phase with a hexagonal shape. The Brunauer–Emmett–Teller (BET) analysis data revealed that ZnO’s surface area and pore size is 22.8[Formula: see text]m2/g and 12.9[Formula: see text]nm, whereas ZnO-C exhibited a surface area of 23.5[Formula: see text]m2/g and pore size of 13.1[Formula: see text]nm. The SEM data demonstrated numerous irregular and agglomerated flakes fusing to form a roughly spherical morphology with the size, in the range of 15–20[Formula: see text]nm and 11–16[Formula: see text]nm for ZnO and ZnO-C NPs, respectively. The results of the antimicrobial assay by disc diffusion method and MIC testing revealed that ZnO and ZnO-C NPs exhibited moderate to high antimicrobial activity against various microorganisms, indicating their application against bacterial infection. In addition, the ZnO NPs significantly disrupted the biofilm of Bacillus cereus and Pseudomonas aeruginosa, as confirmed by CV assay and fluorescent microscopy.

In this work, we report a green synthesis of zinc oxide (ZnO) nanoparticles using aqueous and ethanolic extracts of Tradescantia spathacea (purple maguey) as bioreducing and stabilizing agents, which are plant extracts not previously employed for metal oxide nanoparticle synthesis. This method provides an efficient, eco-friendly, and reproducible route to obtain ZnO nanoparticles, while minimizing environmental impact compared to conventional chemical approaches. The extracts were prepared following a standardized protocol, and their phytochemical profiles, including total phenolics, flavonoids, and antioxidant capacity, were quantified via UV-Vis spectroscopy to confirm their reducing potential. ZnO nanoparticles were synthesized using zinc acetate dihydrate as a precursor, with variations in pH and precursor concentration in both aqueous and ethanolic media. UV-Vis spectroscopy confirmed nanoparticle formation, while X-ray diffraction (XRD) revealed a hexagonal wurtzite structure with preferential (101) orientation and lattice parameters a = b = 3.244 Å, c = 5.197 Å. Scanning electron microscopy (SEM) showed agglomerated morphologies, and Fourier transform infrared spectroscopy (FTIR) confirmed the presence of phytochemicals such as quercetin, kaempferol, saponins, and terpenes, along with Zn–O bonding, indicating surface functionalization. Zeta potential measurements showed improved dispersion under alkaline conditions, particularly with ethanolic extracts. This study presents a sustainable synthesis strategy with tunable parameters, highlighting the critical influence of precursor concentration and solvent environment on ZnO nanoparticle formation. Notably, aqueous extracts promote ZnO synthesis at low precursor concentrations, while alkaline conditions are essential when using ethanolic extracts. Compared to other green synthesis methods, this strategy offers control and reproducibility and employs a non-toxic, underexplored plant source rich in phytochemicals, potentially enhancing the crystallinity, surface functionality, and application potential of the resulting ZnO nanoparticles. These materials show promise for applications in photocatalysis, in antimicrobial coatings, in UV-blocking formulations, and as functional additives in optoelectronic and environmental remediation technologies.

Recently nanotechnology, as an important area of scientific research, has a considerable growth in numerous fields. Biosynthesis of nanoparticles by using plants and microorganisms has received significant attention due to the growing need to develop environmental technologies in nanoparticle synthesis. The green synthesis of nanoparticles is safe for humans and the environment due to lack of pollution. Plants can act as both stabilizing and reducing agents for the synthesis of metal oxide nanoparticles (MO NPs). The research aim is an illustration of a novel method for the synthesis of zinc oxide nanoparticles (ZnO NPs) and copper oxide nanoparticles (CuO NPs) using Achillea Nobilis extract. The crystalline structure and morphology of nanoparticles were studied using characterization techniques such as Fourier transform infrared analysis, ultraviolet–visible spectroscopy studies, X-ray diffraction, field emission scanning electron microscope, and transmission electron microscope methods. The antioxidant activities of ZnO NPs and CuO NPs were evaluated using DPPH assays. Antibacterial activities of nanoparticles were tested against Gram-negative and Gram-positive bacteria using the microdilution method. The results of this study showed that there was a significant relationship between MO NPs resistance and against bacteria.