Stability Of Zinc Oxide Nanoparticles Research Articles

Characterization and stability of zinc oxide nanoparticles stabilized multiphase system composed of red palm oil and water

This study investigated the stability and rheological properties of multiphase systems comprising red palm oil and water, with zinc oxide nanoparticles (ZnO) as stabilizers. Multiphase systems with 60 % and 70 % (v/v) oil contents exhibited excellent physical stability. To achieve a stable multiphase system, a 60 % (v/v) oil content required 1.50 % (w/v) ZnO. However, when the oil content was increased to 70 % v/v, only 0.75 % (w/v) ZnO were required. Increasing ZnO concentration enhanced system stability, as demonstrated by minimal changes in the total carotenoid content and reduced lipid oxidative product formation. Based on rheological characterization, these multiphase systems exhibited shear-thinning flow behavior and viscoelastic properties. The multiphase system consisting of 70 % (v/v) RPO stabilized by 1.50 % (w/v) ZnO was identified as the best multiphase formulation. Conclusively, the findings in this study are valuable insights for formulating stable multiphase systems, composed of red palm oil and water.

Green synthesis of zinc oxide nanoparticles using Pisonia Alba leaf extract and its antibacterial activity

The reducing and capping agent of Pisonia Alba leaf extract were used in a green production of zinc oxide (ZnO) nanoparticles. UV–Vis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with EDS (SEM) were all used to examine the produced ZnO nanoparticles. UV–Vis spectroscopy verified the synthesis of ZnO nanoparticles and their resulting optical characteristics. The UV–Vis spectra showed that the ZnO nanoparticles formed at an absorption peak maximum of 378 nm. Bandgap of the ZnO nanoparticles was also examining. The relevance of Pisonia Alba leaf extract's phenolic chemicals, alkaloids, terpenoids, and proteins in the nucleation and stability of ZnO nanoparticles was proposed by Fourier transform infrared spectroscopy (FTIR). XRD pattern compared with the standard confirmed spectrum of ZnO nanoparticles formed in the present experiments. These results provide further evidence that ZnO has a hexagonal structure (JCPDS-file: 89–1397). There appears to be no contaminants in the ZnO nanoparticles, as evidenced by the XRD pattern. Nanoparticle morphology is investigated with a SEM with EDX. Based on these morphological analyses, ZnO nanoparticles have a similar shape to aloe vera leaves. Oxidation state of the Zn was determined by XPS. The green synthesized ZnO nanopartices were used to evaluate for the antibacterial activity against gram positive and gram negative bacteria. ZnO nanoparticles have potent antimicrobial properties.

Investigating the Antibacterial Activity and Safety of Zinc Oxide Nanoparticles versus a Commercial Alcohol-Based Hand-Sanitizer: Can Zinc Oxide Nanoparticles Be Useful for Hand Sanitation?

Hand hygiene is the key factor to control and prevent the spread of infections, for example, hospital-acquired infections (HAIs). People commonly use alcohol-based hand sanitizers to assure hand hygiene. However, frequent use of alcohol-based hand sanitizers in a pandemic situation (e.g., COVID-19) was associated with serious drawbacks such as skin toxicity including irritation, skin dermatitis, and skin dryness or cracking, along with peeling, redness, or itching with higher possibility of infection. This demands the development of alternative novel products that are effective as alcohol-based hand sanitizers but have no hazardous effects. Zinc oxide nanoparticles (ZnO-NPs) are known to have broad-spectrum antimicrobial activity, be compatible with the biological system and the environment, and have applicable and economic industrial-scale production. Thus, ZnO-NPs might be a good candidate for hand sanitation. To the best of our knowledge, the antibacterial activity of ZnO-NPs in comparison to alcohol-based hand sanitizers has not yet been studied. In the present work, a comparative study of the antibacterial activity of ZnO-NPs vs. Sterillium, a commercial alcohol-based hand sanitizer that is commonly used in Egyptian hospitals, was performed against common microorganisms known to cause HAIs in Egypt, including Acinetobacter baumannii, Klebsiella pneumoniae, Methicillin-resistant Staphylococcus aureus (MRSA), and Staphylococcus aureus. The safety profiles of ZnO-NPs and Sterillium were also assessed. The obtained results demonstrated the superior antibacterial activity and safety of ZnO-NPs compared to Sterillium. Therefore, ZnO-NPs could be a promising candidate for hand sanitation in comparison to alcohol-based hand sanitizers; however, several studies related to long-term toxicity and stability of ZnO-NPs and investigations into their antimicrobial activity and safety in healthcare settings are still required in the future to ascertain their antimicrobial activity and safety.

Biosynthesized Zinc Oxide Nanoparticles Disrupt Established Biofilms of Pathogenic Bacteria

Global emergence and persistence of the multidrug-resistant microbes have created a new problem for management of diseases associated with infections. The development of antimicrobial resistance is mainly due to the sub-judicious and unprescribed used of antimicrobials both in healthcare and the environment. Biofilms are important due to their role in microbial infections and hence are considered a novel target in discovery of new antibacterial or antibiofilm agents. In this article, zinc oxide nanoparticles (ZnO-NPs) were prepared using extract of Plumbago zeylanica. ZnO-NPs were characterized and then their antibiofilm activity was tested against Gram-positive and Gram-negative bacteria. The ZnO-NPs were polydispersed, and the average size was obtained as 24.62 nm. The presence of many functional groups indicated that phytocompounds of P. zeylanica were responsible for the synthesis, capping, and stabilization of ZnO-NPs. Synthesized NPs inhibited the biofilm formation of E. coli, S. aureus, and P. aeruginosa by 62.80%, 71.57%, and 77.69%, respectively. Likewise, concentration-dependent inhibition of the EPS production was recorded in all test bacteria. Microscopic examination of the biofilms revealed that ZnO-NPs reduced the bacterial colonization on solid support and altered the architecture of the biofilms. ZnO-NPs also remarkably eradicated the preformed biofilms of the test bacteria up to 52.69%, 59.79%, and 67.22% recorded for E. coli, S. aureus, P. aeruginosa, respectively. The findings reveal the ability of green synthesized zinc oxide nanoparticles to inhibit, as well as eradicate, the biofilms of Gram-positive and Gram-negative bacteria.

Dispersion stability of zinc oxide nanoparticles in an electroless bath with various surfactants

Stable dispersion of nanoparticles in electrolytes is essential for preparing a wide range of advanced electroless nanocomposites. However, nanoparticles agglomerate if the van der Waals attractive forces prevail over the electrostatic repulsive forces. As a result, various surfactants (anionic, cationic, and non-ionic) were used to prevent nanoparticle agglomeration in the electroless plating bath. This study specifically examines the dispersion stability of zinc oxide (ZnO) nanoparticles in an electroless bath with different surfactants, including anionic sodium dodecyl sulfate (SDS), cationic cetyltrimethylammonium bromide (CTAB), and non-ionic polyvinylpyrrolidone (PVP). The zeta potential and hydrodynamic diameter measurements were utilized as an indicator of nanodispersion stability. The results showed a better-dispersed state of ZnO nanoparticles with SDS surfactant with a small average size of the agglomerate. Surfactants SDS and CTAB improved stability by electrostatic repulsion between ZnO nanoparticles whereas PVP by steric inhibition towards other particles. In addition, ultraviolet–visible absorbance spectroscopy (UV–Vis) was used to examine the dispersion stability of ZnO nanoparticles with different surfactants. The nano-ZnO distributed with SDS displayed a maximum percentage of absorbance, suggesting the homogeneous dispersion of ZnO nanoparticles.

Adsorption, antimicrobial and wound healing activities of biosynthesised zinc oxide nanoparticles

Using plant extracts has been interesting as possible eco-friendly methods to synthesis and stabilize different types of nanoparticles. Zinc oxide nanoparticles (ZnO-NPs) can be used as effective adsorbent due to their high surface area to volume ratio and high spontaneous adsorption properties. In this research, ZnO-NPs were synthesized and stabilized to use as an effective adsorbent material for removing two carcinogenic azo dyes: Malachite green and Congo red. It is also used as an antibacterial active material to enhance mouse skin wound healing. The fabrication and stabilization of ZnO-NPs were performed using Aloe barbadensis leaf extract. The morphology and structure of the as-synthesized ZnO-NPs were investigated by X-ray diffraction, scanning electron microscopy, Fourier transforms infrared spectroscopy and UV–Vis spectroscopy. The fabricated ZnO-NPs were applied as an adsorbent for the removal of Malachite green, a cationic azo dye, and Congo red, an anionic azo dye. The ZnO-NPs achieved adsorption efficiency of 90.7% for Malachite green azo dye within 90 min at the maximum amount of 70 mg/ml. Congo red dye was adsorbed at the efficiency of 92.30% within 120 min at 80 mg/ml maximum concentration of ZnO-NPs. Using the batch process, different parameters (time, pH, amount of adsorbent) during the adsorption process were elucidated. The results confined the applicability of ZnO-NPs as an efficient adsorbent for Malachite green and Congo red dyes. Also, the synthesised ZnO-NPs demonstrated a powerful antimicrobial activity against four types of bacterial strains of Bacillus subtilis, Klebsiella pneumonia, Bacillus licheniformis and Escherichia coli, and two types of fungi strains of Aspergillus niger and Candida albicans. The healing efficiency of mouse wound was studied using ZnO-NP/silica gel (ZnO-NP/SG) dressings due to its extensive evidence on healing property. The microscopic investigations of the wound area are reduced significantly using ZnO-NP/SG-30 ppm dressings within 11 days of observation as compared to ZnO-NPs of the control sample. These findings elaborated that as-synthesized dressing enhanced the skin repairing on the wound surface and support its usage in the future.

Influence of NOM on the Stability of Zinc Oxide Nanoparticles in Ecotoxicity Tests

Nanomaterials are known to aggregate in the presence of ions. Similarly, the aggregation of zinc oxide nanoparticles (ZnO NPs) exposed to various ions such as sodium chloride and calcium chloride in water systems increases with the ionic strength. Therefore, for accurate toxicity studies, it is necessary to conduct a test using natural organic matters (NOMs) as additional dispersants that strengthen stability with increased repulsive forces. The three types of ecotoxicity tests based on the dispersion stability test using NOM showed that the toxicities of the three test samples decreased in the presence of NOM. To determine how NOM improved dispersion and reduced toxicities, we analyzed the ionization degree of ZnO NPs with and without NOM and found that the solubility was below 2 mg/L with a negligible change over time, implying that the ionization effect was low. The absolute value of the surface charge of particles increased in the presence of NOM, resulting in increased repulsive electrostatic forces and steric hindrance, causing less aggregation and more dispersion. Additionally, although the NOM used in the test is considered an effective dispersant that does not have a toxicological effect on aquatic organisms, the presence of NOM resulted in reduced toxicities and should be further investigated to establish it as a standard test method.

Biogenic Synthesis of Zinc Oxide Nanoparticles by Bryophyllum pinnatum and its Acute Oral Toxicity Evaluation in Wistar Rats.

The evaluation of toxic effects of nanoparticles (NPs) has become an important aspect of Nanotechnology research in the 21st century. The present investigation deals with the green synthesis of biogenic zinc oxide nanoparticles (ZnO-NPs) using Bryophyllum pinnatum leaves, their characterization and evaluation of acute oral toxicity in Wistar rats. The characterization of synthesized ZnO-NPs revealed maximum absorbance at 307 nm on UV-Vis spectrophotometric analysis, NTA showed mean size of particles and mode of the particles distribution as 128.2 nm and 12.6 nm, respectively. Zeta potential was found to be -0.369 mV. The absorbance shown by FTIR at 3469, 1644, 1355 and 887 cm-1 indicates the involvement of biomolecules that are accountable for capping and stabilization of ZnO-NPs. The XRD assessment further demonstrated the crystalline nature of the ZnO-NP. The TEM analysis of the synthesized ZnO-NPs revealed the presence of spherical NPs with the mean size of 3.7 nm. The acute oral toxicity evaluation in rat showed an approximate median lethal dose to be more than 2000 mg/kg body weight. It is thus concluded that biogenic ZnO-NPs showed absence of acute oral toxicity symptoms at the doses employed in the present study.

Anticancer and apoptotic activity of biologically synthesized zinc oxide nanoparticles against human colon cancer HCT-116 cell line- in vitro study

Aim of this study was to synthesize the safe and stable zinc oxide nanoparticles (ZnONPs) from the leaves of Artocarpus heterophyllus. The alter in the color of the leaf extract dark brown upon addition of zinc nitrate Zn(NO3) confirms the formation of Zinc Oxide nanoparticles (ZnONPs). UV-VIS spectrophotometric analysis showed lambda max at 235 nm while Fourier transform infra-red (FTIR) spectroscopy showed various amines and amides are involved in the stabilization of ZnONPs. Energy dispersive X –rays (EDX) confirms the presence of zinc. Transmission electron microscopy (TEM) analysis revealed particle size ranges from 12 to 24 nm. These observed characteristic of nanoparticles are extremely useful in anticancer activities against HCT-116 colon cancer cell line. These ZnONPs showed IC50 value at 20μg/ml while on normal Vero cell line showed less effective by MTT assay. Furthermore, these nanoparticles were evaluated for apoptotic activity by acridine orange/ethidium bromide (AO/EB) double staining method showed the membrane blebbing and chromatin condensation.

Biosynthesis of zinc oxide nanoparticles using Albizia lebbeck stem bark, and evaluation of its antimicrobial, antioxidant, and cytotoxic activities on human breast cancer cell lines.

BackgroundBiocompatibility and stability of zinc oxide nanoparticles (ZnO NPs) synthesized using plants is an interesting research area of study in nanotechnology, due to its wide applications in biomedical, industrial, cell imaging, and biosensor fields. The present study reports the novel green synthesis of stable ZnO NPs using various concentrations of zinc nitrate (0.01M, 0.05M, 0.1M) and Albizia lebbeck stem bark extracts as an efficient chelating agent. Antimicrobial, antioxidant, cytotoxic, and antiproliferative activities of the synthesized NPs on human breast cancer cell lines were evaluated using different assays.MethodsCharacterization of the synthesized ZnO NPs were carried out using various spectroscopic and microscopic techniques. Antimicrobial activity evaluation using disc diffusion method, antioxidant activity using hydrogen peroxide (H2O2) free radical scavenging assay and cytotoxic activity on MDA-MB 231 and MCF-7 using tryphan blue dye exclusion and MTT assay.ResultsThe UV–vis spectroscopy result revealed an absorption peak in the range of 370 nm. The involvements of A. lebbeck bioactive compounds in the stabilization of the ZnO NPs were confirmed by X-ray diffraction and Fourier transform infrared analysis. Zeta sizer studies showed an average size of 66.25 nm with a polydisparity index of 0.262. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses results revealed irregular spherical morphology and the presence of primarily Zn, C, O, Na, P, and K, respectively. The biosynthesized ZnO NPs revealed strong antimicrobial potentials against various gram-negative and gram-positive bacterial pathogens. Antioxidant activities carried out using H2O2 free radical scavenging assay revealed higher IC50 values of 48.5, 48.7, and 60.2 µg/mL for 0.1M, 0.05M, and 0.01M ZnO NPs, respectively. Moreover, the biosynthesized ZnO NPs showed significant cytotoxic effects on MDA-MB 231 and MCF-7 breast cancer cell lines (P< 0.001, n≥3) in a concentration-dependent manner.ConclusionOverall, various concentrations of ZnO NPs were synthesized through a stable, simple, and eco-friendly green route via the use of A. lebbeck stem bark extract. The biosynthesized ZnO NPs showed strong antimicrobial, antioxidant and cytotoxic activity against strongly and weakly metastatic breast cancer cell lines.

Melatonin-stimulated biosynthesis of anti-microbial ZnONPs by enhancing bio-reductive prospective in callus cultures of Catharanthus roseus var. Alba

Melatonin as plant growth regulator induces differential effects on metabolites that are responsible for reduction, capping and stabilization of zinc oxide nanoparticles. Phytochemical analysis of callus cultures was performed and results were compared with callus cultures supplemented with other plant growth regulators (α-napthalene acetic acid, 2,4-dichlorophenoxy acetic acid and thidiazuron). Highest total phenolic and flavonoid content [42.23 mg of gallic acid equivalent (GAE) g−1 DW and 36.4 mg of (quercetin equivalent) g−1 DW, respectively] were recorded at melatonin (1.0 µM) + NAA (13.5 µM). ZnONPs were synthesized from NAA (13.5 µM) and melatonin (1.0 µM) + NAA (13.5 µM)-induced calli extracts separately and characterized via X-ray diffraction, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). FTIR analysis confirmed the presence of phenolics and flavonoids that were mainly found responsible for reduction and capping of ZnONPs. SEM analysis showed triangular shaped ZnONPs synthesized from melatonin + NAA callus extract and these NPs were more dispersed as compared to the spherical-agglomerates of ZnONPs synthesized from NAA-mediated callus extract. Melatonin + NAA callus extract-mediated ZnONPs (having smaller size) were more potent against multiple drug resistant bacterial strains, e.g. Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa by producing zone of inhibitions 17 ± 0.76 mm,10 ± 0.57 mm and 13 ± 0.54 mm, respectively.

Methane hydrate formation in the presence of ZnO nanoparticle and SDS: Application to transportation and storage

Due to natural gas benefits such as less carbon dioxide production compared to the other fossil fuels, its transmission technologies to the market are noticed these years and gas hydrate storage method could be considered as an option to storage and transportation. One way to overcome the low rate gas hydrate formation is using a mixture of surfactant and nanoparticles to enhance the hydrate formation rate. Hence, in this present contribution sodium dodecyl sulfate (SDS) (as a surfactant) and zinc oxide nanoparticles are used to promote hydrate formation process. The experiments were carried out at the temperature of 274.65 and 276.65 K, and the initial pressure of 50 and 60 bar in different additives concentrations. The results show that these additives can increase the amount of methane consumed, the rate of methane consumed and the mole number of water to hydrate conversion increases, however, these additives do not significantly affect the gas hydrate storage. Moreover, experimental results reveals that addition of SDS to the water not only improve the stabilization of zinc oxide nanoparticles in water but also increases the solubility of methane in water by lowering the surface tension. Also, as the novel outcome, these additives (SDS+ ZnO nanoparticles) decrease the induction time, however, the final storage capacity does not change significantly.

Nanoparticles surface treatment on cemented materials for inhibition of bacterial growth

Bacterial growth on cemented materials such as concrete can cause degradation and early ageing. This paper explores the bactericidal characteristics of cementitious materials surface treated with zinc oxide (ZnO) and silver (Ag) nanoparticles. The growth of gram positive Bacillus cereus and gram negative Escherichia coli has been monitored. The growth inhibitory performance of nanoparticles against two model bacteria was further examined at different surface pH of mortar samples and different bacterial cell densities. After the seven-day experimental period, more than 60% reduction in the number of viable cells of both model bacteria was obtained at all tested pH values when nanoparticles with a concentration of 250mg/l were added at the beginning of culturing time. However, delayed addition of nanoparticles at the mid-logarithmic growth phase, i.e., higher cell densities, resulted in less growth inhibition. Ag nanoparticles showed the highest inhibition due to the high degree of nanoparticle stability and uniform particle size. On the other hand, the stability of ZnO nanoparticles in the experimental mixture was significantly influenced by the pH change and aggregation, which resulted in lower inhibition efficiencies. Gram-positive Bacillus cereus was found to be less sensitive to both tested nanoparticles, compared with Gram-negative Escherichia coli. The experiment demonstrates the efficacy of nanoparticles in inhibiting bacterial growth on cementitious materials.

Functionalization of ZnO nanoparticles by 3-mercaptopropionic acid for aqueous curcumin delivery: Synthesis, characterization, and anticancer assessment

Inherent biocompatibility and stability of zinc oxide nanoparticles (ZnO-NPs) and their biomedical potentials make them an emerging candidate for drug delivery. The aim of this study was to develop and assess a simple procedure for surface functionalization of ZnO-NPs by 3-mercaptopropionic acid (MPA) for water-soluble curcumin delivery. Carboxyl-terminated ZnO nanoparticles were successfully made using ZnCl2 and NaOH in the presence of MPA. The functional groups were activated by 1,1′-carbonyldiimidazole (CDI) and the curcumin bonding was carried out at room temperature for 24h. The core-shell nanocomposite had a significant better solubility versus free curcumin, as characterized by XRD, FTIR, UV–Vis spectrophotometry, DLS, and TEM, p<0.005. In addition, MTT cytotoxicity assessment on MDA-MB-231 breast cancer cells revealed a drop of IC50 values from 5μg/mL to 3.3μg/mL for free curcumin and ZnO-MPA-curcumin complex, respectively. This result showed an augmented cancer-inhibitory effect of nanoconjugate complex. In conclusion, the presented improved solubility and elevated functionality of novel ZnO-MPA-curcumin nanoformula is promising, and could be considered for new therapeutic endeavors.

Limonia acidissima L. leaf mediated synthesis of zinc oxide nanoparticles: A potent tool against Mycobacterium tuberculosis

Objective/backgroundThe present investigation was undertaken to synthesize zinc oxide nanoparticles using Limonia acidissima L. and to test their efficacy against the growth of Mycobacterium tuberculosis. MethodsThe formation of zinc oxide nanoparticles was confirmed with UV–visible spectrophotometry. Fourier transform infrared spectroscopy shows the presence of bio-molecules involved in the stabilization of zinc oxide nanoparticles. The shape and size was confirmed with atomic force microscope, X-ray diffraction, and high resolution transmission electron microscope. These nanoparticles were tested for their effect on the growth of M. tuberculosis through the microplate alamar blue assay technique. ResultsThe UV–visible data reveal that an absorbance peak at 374nm confirms formation of zinc oxide nanoparticles and they are spherical in shape with sizes between 12nm and 53nm. These nanoparticles control the growth of M. tuberculosis at 12.5μg/mL. ConclusionPhytosynthesis of zinc oxide nanoparticles is a green, eco-friendly technology because it is inexpensive and pollution free. In the present investigation, based on our results we conclude that the aqueous extract of leaves of L. acidissima can be used for the synthesis of zinc oxide nanoparticles. These nanoparticles control the growth of M. tuberculosis and this was confirmed with the microplate alamar blue method. The potential of biogenic zinc oxide nanoparticles may be harnessed as a novel medicine ingredient to combat tuberculosis disease.

RETRACTED: Influence of humic acid on the stability and bacterial toxicity of zinc oxide nanoparticles in water

The present study investigated the stability of zinc oxide nanoparticles (ZnO NPs) by the adsorption of humic acid (HA) and the mechanism of adsorption. The effect of humic acid on NP toxicity was determined by Escherichia coli (ATCC 13534), E. coli (ATCC 25922), and Pseudomonas putida (MTCC 4910). The nanoparticles showed low zeta potential and were least stable in the absence of HA. However, the negative surface charge of the particles increased in the presence of HA (0-50mg/L) that reduced the propensity of nanoparticles to aggregate in water. A decrease in absorbance of ZnO NPs at 375 nm (plasmon peak) was noted in the presence of HA by UV-visible spectrophotometric analysis. A blue shift towards 370 nm was noted when the concentration of HA was above 20mg/L. The HA adsorbed ZnO NPs showed higher zeta potential (>-30 mV) and were highly stable. HA reduced the photocatalytic activity of ZnO and at the same time increased the photostability of ZnO.

Extracellular synthesis of zinc oxide nanoparticle using seaweeds of gulf of Mannar, India.

BackgroundThe biosynthesis of metal nanoparticles by marine resources is thought to be clean, nontoxic, and environmentally acceptable “green procedures”. Marine ecosystems are very important for the overall health of both marine and terrestrial environments. The use of natural sources like Marine biological resources essential for nanotechnology. Seaweeds constitute one of the commercially important marine living renewable resources. Seaweeds such as green Caulerpa peltata, red Hypnea Valencia and brown Sargassum myriocystum were used for synthesis of Zinc oxide nanoparticles.ResultThe preliminary screening of physico-chemical parameters such as concentration of metals, concentration of seaweed extract, temperature, pH and reaction time revealed that one seaweed S. myriocystum were able to synthesize zinc oxide nanoparticles. It was confirmed through the, initial colour change of the reaction mixture and UV visible spectrophotometer. The extracellular biosynthesized clear zinc oxide nanoparticles size 36 nm through characterization technique such as DLS, AFM, SEM –EDX, TEM, XRD and FTIR. The biosynthesized ZnO nanoparticles are effective antibacterial agents against Gram-positive than the Gram-negative bacteria.ConclusionBased on the FTIR results, fucoidan water soluble pigments present in S. myriocystum leaf extract is responsible for reduction and stabilization of zinc oxide nanoparticles. by this approach are quite stable and no visible changes were observed even after 6 months. These soluble elements could have acted as both reduction and stabilizing agents preventing the aggregation of nanoparticles in solution, extracellular biological synthesis of zinc oxide nanoparticles of size 36 nm.