Algal Extracts for Green Synthesis of Zinc Oxide Nanoparticles: Promising Approach for Algae Bioremediation

Zinc oxide (ZnO) nanoparticles (NPs) were fabricated by using leaves extracted from the thyme plant by employing a green method. The influence of several calcination (annealing) temperatures on the characteristic properties of fabricated ZnO NPs and the optimum calcination temperature for growing ZnO NPs were studied and reported. The studied calcination temperatures were 150 °C, 250 °C, 350 °C, and 450 °C. Different characterization techniques were used to study and examine the properties of biosynthesized ZnO NPs by using thyme plant leaf extract. The results of each UV-Vis analysis and FTIR spectrum of the leaf extract of the thyme plant confirmed and suggested that the selected leaf extract of thyme is a practicable choice for green synthesis of ZnO NPs. The investigated UV-Vis spectra of plant leaf extract displayed two strong absorption peaks at 266 nm and 313 nm at ambient temperature. The results of FESEM images showed that the calcination temperature has a significant and large effect on the morphology, size, shape, and orientation of ZnO NPs, which have a spherical shape with an average size in the range of 39.4–51.86 nm. In addition, the XRD results confirm that the ZnO NPs formed are pure ZnO with wurtzite hexagonal structure with particle size along the (002) peak in the range of 35.20–243.3 nm. The results of UV-Vis of ZnO NPs displayed a strong peak for all ZnO NPs produced at different calcination temperatures, a high absorbance in the UV region below 400 nm, and a low absorbance rate in the visible range. The obtained energy band gap (Eg) was in the range of 2.645–2.7 eV. In addition, the results of the FTIR spectra of ZnO NPs at different calcination temperatures revealed there was no discernible peak in the monitoring range, which indicated the purity of the ZnO nanoparticles generated via using thyme leaf extract. In addition, from all obtained results of the fabricated ZnO NPs, the ZnO NPs synthesized at the calcination temperature of 450 °C showed a high quality and improvement compared to the ZnO NPs synthesized at other calcination temperatures.

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.

Background: Corrosion is a pervasive issue affecting various industries, resulting in significant economic losses.Traditional corrosion protection methods often involve toxic chemicals, prompting the need for eco-friendly alternatives.This study demonstrates the green synthesis of zinc oxide (ZnO) nanoparticles via a sol-gel approach and their integration into epoxy resin coating to enhance anticorrosion efficacy.Objectives: This study aims to synthesize ZnO nanoparticles using a green synthesis method, characterize their properties, and evaluate their potential applications in corrosion protection and biomedical fields. Methods:The synthesized nanoparticles were characterized using x-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and high-resolution transmission electron microscopy (HRTEM).The ZnO nanoparticles were then integrated into epoxy resin to develop a nanocoating optimized for enhanced performance. Results:The XRD analysis revealed the formation of a spherical zincite ZnO phase with an average crystallite size of 16.7 nm.HRTEM confirmed the average particle size of 16.3 nm, with uniform morphology.Electrochemical impedance spectroscopy (EIS) analysis demonstrated the exceptional corrosion resistance of the ZnO/epoxy resin coating.The green synthesis method produced uniform ZnO nanoparticles successfully integrated into the epoxy resin coating.The resulting nano-coating exhibited enhanced corrosion resistance, making it a promising solution for protecting metal surfaces. Conclusion:This study demonstrates the green synthesis of ZnO nanoparticles using a sol-gel approach.The synthesized nanoparticles were characterized using XRD, EDS, and HRTEM.The ZnO nanoparticles were then integrated into epoxy resin to develop a nanocoating optimized for enhanced corrosion resistance.The results show that the ZnO/epoxy resin coating exhibits exceptional corrosion resistance, making it a promising solution for protecting metal surfaces.

The green synthesis of zinc oxide (ZnO) nanoparticles has gained significant attention due to its environmentally friendly approach. This study focuses on the synthesis of ZnO nanoparticles using an aqueous extract of Origanum vulgare (oregano) as a natural reducing and stabilizing agent. The use of plant extracts in nanoparticle synthesis offers advantages such as simplicity, cost-effectiveness, and the elimination of toxic chemicals. The synthesized ZnO nanoparticles were characterized using various techniques such as UV-Vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) to determine their size, structure, and morphology. The results demonstrated that the ZnO nanoparticles were crystalline with a hexagonal wurtzite structure, and the average particle size ranged from 50 to 70 nm. The findings underscore the potential of Origanum vulgare for the eco-friendly synthesis of ZnO NPs, which could have applications in biomedicine, catalysis, and environmental remediation.

This study focused on the green synthesis of zinc oxide nanoparticles (ZnO-NPs) using the aqueous extract of C. graveolens and evaluated their antidiabetic activity. The extract served as both a reducing and capping agent. Synthesized ZnO-NPs were characterized by FTIR, XRD, SEM, and Zetasizer to determine their structural, morphological, and optical properties. Characterization confirmed the successful formation of spherical, crystalline ZnO-NPs with sizes ranging from 20-50 nm. FTIR spectra indicated the role of hydroxyl and carbonyl groups in nanoparticle stabilization. The antidiabetic activity of the ZnO-NPs was assessed through in vitro alpha-glucosidase and alpha-amylase inhibition assays. A concentration-dependent increase in alpha-glucosidase inhibition was observed, with inhibition rates of 67.8% at 50 µg/mL and 86.9% at 100 µg/mL. Similarly, alpha-amylase inhibition reached 81.7% at 100 µg/mL. These findings suggest that the enhanced activity may be due to the synergistic effects of zinc ions and phytochemicals from the plant extract. Overall, green-synthesized ZnO-NPs from C. graveolens demonstrate significant in vitro antidiabetic potential via dual enzyme inhibition. Further in vivo and clinical studies are recommended to confirm their therapeutic efficacy and safety, positioning them as a natural and cost-effective approach for managing type 2 diabetes.

Green synthesis, characterization, structural, morphological, antibacterial, and cytotoxicity evaluation of zinc oxide nanoparticles using Fioria vitifolia extract.

Abstract: In this work, zinc oxide (ZnO) nanoparticles are synthesised and characterised in an environmentally friendly manner, and their potential uses in photocatalytic processes is investigated. The green synthesis of ZnO nanoparticles involved the utilization of zinc nitrate hexahydrate (Zn(NO3)2·6H2O) and Nyctanthes arbor-tristis Plant Extracts. The nanoparticles were synthesized at an optimal temperature of 60 ◦C. The samples were analysed using energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), Dynamic Light Scattering(DLS) and UV-visible spectroscopy to determine their characteristics. ZnO nanoparticles were identified by a distinctive peak at 302 nm in UV-visible spectroscopy. SEM confirmed the nanoscale size and morphology of the ZnO particles. The elemental information obtained from the EDX examination showed that oxygen made up 22.2% of the atomic weight and zinc made up 45.6%. The diffractogram was indexed by XRD analysis at different angles that corresponded to ZnO nanoparticles. DLS determined the average crystalline size, which was 87.5 nm. FTIR examination revealed a distinctive signal at 1051 cm−1, suggesting that the nanoparticles contain functional groups. The produced nanoparticles had strong photocatalytic activity, especially when Methyl Blue was exposed to UV light and began to degrade. Rate constants and correlation coefficients were used to examine how the addition of ZnO nanoparticles affected the photocatalytic degradation process' kinetics. These nanoparticles were synthesised using an economical and ecologically friendly process. This work offers potential directions for further investigation and applications in the fields of nanotechnology, biosensor development, and water remediation.

Metallic nanoparticles are of growing interest due to their broad applications. This study presents the green synthesis of zinc oxide (ZnO) nanoparticles (ZnNPs) using Ganoderma Lucidum mushroom extract, characterized by DLS, SEM, XRD, and FTIR spectroscopy analyses. The synthesis parameters, including extract/salt ratio and mixing time, significantly influenced nanoparticle yield, size, and polydispersity, with longer mixing times leading to larger, more varied particles. Specifically, the sizes of ZnNPs synthesized at a 1:1 extract/ZnCl2 ratio after 3 h and 24 h were 90.0 nm and 243.3 nm, with PDI values of 48.69% and 51.91%, respectively. At a 1:2 ratio, the sizes were 242.3 nm at 3 h (PDI: 43.19%) and a mixture of 1.5 nm, 117.4 nm, and 647.9 nm at 24 h (PDI: 2.72%, 10.97%, and 12.43%). Polymer films incorporating PVA, chitosan, and ZnNPs were analyzed for their morphological, spectroscopic, and mechanical properties. Chitosan reduced tensile strength and elongation due to its brittleness, while ZnNPs further increased film brittleness and structural degradation. A comparison of the tensile strength of films A and C revealed that the addition of chitosan to the PVA film resulted in an approximately 10.71% decrease in tensile strength. Similarly, the analysis of films B1 and B2 showed that the tensile strength of the B2 film decreased by 10.53%. Swelling tests showed that ZnNPs initially enhanced swelling, but excessive amounts led to reduced capacity due to aggregation. This pioneering study demonstrates the potential of Ganoderma Lucidum extract in nanoparticle synthesis and provides foundational insights for future research, especially in wound dressing applications.

The green synthesis of Zinc Oxide (ZnO) nanoparticles is a simpler, low-energy method that avoids toxic chemicals, making the process more cost-effective and environmentally friendly. The green synthesis was performed using aloe vera extract (55% - Aloin), rich in electrons from its hydroxyl groups, as a reducing agent, and natural polysaccharides from xanthan gum to disperse particles and prevent agglomeration. The green synthesis product was characterized using scanning electron microscopy, Fourier Transform spectroscopy, X-ray diffraction, transmission electron microscopy, and Diffuse Reflectance UV spectroscopy. The green-synthesized ZnO nanoparticles, both with xanthan gum (ZnO-AL/XG) and without xanthan gum (ZnO-AL), adopted a hexagonal wurtzite crystal structure. The addition of xanthan gum significantly reduced the crystallite size and enhanced the surface homogeneity of the photocatalyst. Over 50% removal of both anionic and cationic dyes was achieved by ZnO-AL/XG for up to 3 uses, and by ZnO-AL for up to 2 uses, respectively. These findings highlight the potential of the aloe vera–xanthan gum-based green synthesis as a sustainable and efficient strategy for producing ZnO nanomaterials applicable in dye wastewater treatment. Copyright © 2026 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Objectives: Zinc oxide (ZnO) nanoparticles have received considerable attention due to their antimicrobial, UV blocking, and high catalytic and photochemical activities. Hence, an investigation has been carried out to synthesize the ZnO nanoparticle using aqueous Phyllanthus niruri (Keezhanelli) leaf extract. Aims and objectives of the present study are to synthesize using Keezhanelli (P. niruri) leaf extract, to study its characterization, and to determine its antibacterial activity.
 Methods: Green synthesized ZnO nanoparticle was characterized by Fourier transform infrared (FTIR), scanning electron microscope (SEM), and transmission electron microscope (TEM) analysis. Antimicrobial activity of ZnO nanoparticle was carried out using agar well diffusion method.
 Results: The result of the synthesized ZnO nanoparticle using Keezhanelli (P. niruri) leaf extract showed the change of color from pale white to brown color. The result of FTIR analysis of green synthesized ZnO nanoparticle revealed the presence of biomolecules such as polyphenols, flavonoids, alkaloids, polysaccharide, amino acid, and proteins. The result of the SEM studies showed that the green synthesized ZnO nanoparticle was spherical and cylindrical in shape. The size of the ZnO nanoparticle was recorded to be 5 μm. The result of TEM studies of ZnO nanoparticle showed that majority of the particles were spherical in shape with the size of 2 μm. The result of antibacterial activity against four bacterial species showed that green synthesized ZnO nanoparticle was found to be efficient in inhibiting the growth of the bacterial isolates. Maximum zone formation was exhibited against Staphylococcus saprophyticus. 
 Conclusion: Thus, from the results of the present study, it can be concluded that synthesis of ZnO nanoparticle using leaf extract of Keezhanelli (P. niruri) has several advantages such as simple, cost-effective, time consuming, safe, and eco-friendly compared to other methods of nanoparticle synthesis as evidenced in the present study.

Green synthesis of ZnO nanoparticles using Abutilon Indicum and Tectona Grandis leaf extracts for evaluation of anti-diabetic, anti-inflammatory and in-vitro cytotoxicity activities

Green synthesized Gmelina arborea Roxb leaves ZnO nanoparticles: DNA fingerprinting, phytochemistry, greenness and biological activities.

Objective(s): This study was aimed to investigate the synthesis of novel zinc oxide (ZnO) nanoparticles (NPs) using Solanum trilobatum leaf extract as the reducing and capping agents, called green synthesized zinc oxide nanoparticles (GS-ZnONPs). <br />Materials and Methods: Chemically synthesized zinc oxide nanoparticles (CS-ZnONPs) were synthesized using precipitation method with zinc nitrates hexahydrate as reducing precursors. The synthesized GS- and CS-ZnONPs were examined and characterized using UV-visible spectroscopy, Transmission Electron Microscopy (TEM), Scanning Electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), and X-ray diffraction (XRD) analysis, respectively. <br />Results: GS-ZnONPs exhibited a higher zone of inhibition of 28.6 mm, 27.63 mm, and 29.33 mm for Bacillus subtilis, Escherichia coli, and Klebsiella pneumoniae, respectively compared to CS-ZnONPs. From the growth inhibition experiments with E. coli and Staphylococcus aureus, it was evident that GS-ZnONPs have exhibited higher growth inhibition as compared to CS-ZnONPs. The IC50 for CS-ZnONPs in MCF-7 cell line was found at 136.16 µg/mL and for GS-ZnONPs was found at 85.05 µg/mL. The proliferation of cancer cells were directly proportional to the concentration of NPs. As compared to CS-ZnONPs, GS-ZnONPs have exhibited higher cytotoxic effects on MCF-7 cell line. <br />Conclusion: It was concluded that GS-ZnONPs represented much enhanced anticancer and antibacterial activity compared to CS-ZnONPs.

Due to their distinctive characteristics and widespread application across all scientific disciplines, nanoparticles have attracted a lot of attention in the current millennium. Green synthesis of ZnO-NPs is gaining a lot of interest at the moment due to a number of its advantages over traditional methods, including being quicker, less expensive, and more environmentally friendly. In the current study, two distinct plant extracts are used to quickly, cheaply, and environmentally friendly synthesize zinc oxide nanoparticles (ZnO-NPs). Mint (Mentha spicata) and basil (Ocimum basilicum) were the plants employed in this study as stabilizing agents to synthesize ZnO-NPs with a green chemistry approach. The innovative aspect of the study is the use of mint and basil extracts in the conversion of zinc chloride to zinc oxide and then determining the effect of these two types of nanoparticles produced by green synthesis on the growth parameters of the plant when they reach the plants by foliar spraying and their uptake by plants and evaluating the antibacterial properties of these nanoparticles. The physical properties of the produced nanoparticles were investigated using XRD, SEM, and FTIR. Moreover, Escherichia coli and Staphylococcus aureus were used to demonstrate the antibacterial properties of ZnO-NPs against both gram-positive and gram-negative bacteria, respectively. Synthesized ZnO-NPs were also given as foliar treatment in order to determine Zn+2 uptake by plants and potential toxic effects on the growth of wheat. The shape of ZnO-NPs was triangular, as revealed by SEM analysis. In the X-ray diffraction study, strong and clearly discernible sharp peaks were seen, with an average size of 24.5 nm for M-ZnO-NPs and 26.7 nm for B-ZnO-NPs determined using Scherrer's formula. The phytoconstituents of the plant extract served as capping/stabilizing agents during the synthesis of ZnO-NPs, as demonstrated by Fourier transform-infrared spectroscopy. The produced nanoparticles were applied to the green parts of wheat plants by spraying, and the development of the plants and the change of zinc uptake were investigated. At the same time, the effect of these three types of nanoparticles on the germination of wheat seeds in the soil medium containing these nanoparticles was investigated. According to experimental results, M-ZnO-NPs (produced from mint) and B-ZnO-NPs (produced from basil) improved the germination percentage of wheat at 400 mg/L concentration (100%), while raw ZnO-NPs showed 90% germination at the same concentration. When the Zn+2 uptake of the plant by the leaves depending on the Zn+2 concentration in the environment after spraying was examined, it was determined that the Zn+2 uptake of the plants increased due to the increase in the applied Zn+2 concentration. The highest Zn+2 uptake of the plant was determined as 50, 25, and 50 mg/L for M-ZnO-NP, B-ZnO-NPs, and raw ZnO-NPs, respectively. Therefore, it has been determined that plant growth varies depending on the type and concentration of ZnO-NPs, and therefore, if foliar nanoparticle applications are made to wheat, the threshold concentrations, sizes, and types of ZnO-NPs should be carefully evaluated. In addition, antibacterial properties results showed that S. aureus was more sensitive to all three types of ZnO-NPs than E. coli.

Phytofabricated green synthesis of zinc oxide (ZnO) nanoparticles using different plant extracts of Azadirachta indica, Hibiscus rosa-sinensis, Murraya koenigii, Moringa oleifera, and Tamarindus indica for biological applications has been reported. ZnO nanoparticles were also synthesized by chemical method to compare the efficiency of the green synthesized nanoparticles. FT-IR spectra confirmed the functional groups involved in the green synthesis of ZnO nanoparticles and the powder XRD patterns of the ZnO nanoparticles revealed pure wurtzite structure with preferred orientation at (100) reflection plane. SEM and TEM analysis revealed the spherical shape of the synthesized ZnO nanoparticles with the particle size between 54 and 27nm. The antioxidant activity was evaluated by five different free radical scavenging assays. The present study also intends to screen α-amylase and α-glucosidase activity of ZnO nanoparticles synthesized using natural sources, which may minimize the toxicity and side effects of the inhibitors used to control diabetes. The ZnO nanoparticles synthesized using T. indica extract displayed remarkable antioxidant and antidiabetic activities.