Synthesis, Characterization, and Spectroscopic Properties of ZnO Nanoparticles

The development of reliable processes for the synthesis of zinc oxide nanoparticles is an important aspect of nanotechnology today. Zinc oxide nanoparticles comprise well-known inhibitory and bactericidal effects. Emergence of antimicrobial resistance by pathogenic bacteria is a major health problem in recent years. The present study is concerned about the synthesis, characterization of zinc oxide nanoparticles, and their use as antibacterial agent. Zinc oxide nanoparticles were synthesized by chemical (precipitation) method using zinc nitrate and NaOH. The synthesized zinc oxide nanoparticles were characterized with scanning electron microscope and X-ray diffraction analysis. The antimicrobial activity of zinc oxide nanoparticles was tested against human pathogens like Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Enterococcus faecalis, and Pseudomonas aeruginosa using well diffusion method. Similarly, the antibacterial activity of standard antibiotics was tested against human pathogens using the disc diffusion method. The efficiency of zinc oxide nanoparticles was compared with that of standard antibiotics. The results showed that zinc oxide nanoparticles have strong antimicrobial activity against all tested pathogens. The antibacterial activity increased with increasing concentration of zinc oxide nanoparticles. The results of the study confirmed that the zinc oxide nanoparticles may serve as promising antibacterial agents.

In this study, GNF@ZnO composites (gelatin nanofibers (GNF) with zinc oxide (ZnO) nanoparticles (NPs)) as a novel antibacterial agent were obtained using a wet chemistry approach. The physicochemical characterization of ZnO nanoparticles (NPs) and GNF@ZnO composites, as well as the evaluation of their antibacterial activity toward Gram-positive (Staphyloccocus aureus and Bacillus pumilus) and Gram-negative (Escherichia coli and Pseudomonas fluorescens) bacteria were performed. ZnO NPs were synthesized using a facile sol-gel approach. Gelatin nanofibers (GNF) were obtained by an electrospinning technique. GNF@ZnO composites were obtained by adding previously produced GNF into a Zn2+ methanol solution during ZnO NPs synthesis. Crystal structure, phase, and elemental compositions, morphology, as well as photoluminescent properties of pristine ZnO NPs, pristine GNF, and GNF@ZnO composites were characterized using powder X-ray diffraction (XRD), FTIR analysis, transmission and scanning electron microscopies (TEM/SEM), and photoluminescence spectroscopy. SEM, EDX, as well as FTIR analyses, confirmed the adsorption of ZnO NPs on the GNF surface. The pristine ZnO NPs were highly crystalline and monodispersed with a size of approximately 7 nm and had a high surface area (83 m2/g). The thickness of the pristine gelatin nanofiber was around 1 µm. The antibacterial properties of GNF@ZnO composites were investigated by a disk diffusion assay on agar plates. Results show that both pristine ZnO NPs and their GNF-based composites have the strongest antibacterial properties against Pseudomonas fluorescence and Staphylococcus aureus, with the zone of inhibition above 10 mm. Right behind them is Escherichia coli with slightly less inhibition of bacterial growth. These properties of GNF@ZnO composites suggest their suitability for a range of antimicrobial uses, such as in the food industry or in biomedical applications.

Nanostructured particles offer outstanding diversities of applications in the fields of nanotechnology, nano-engineering, nano-biotechnology, etc. Morphological structure, size distribution, electronic behavior including intrinsic characteristics of nanoparticles depend on the source and synthesis methods. Here, an eco-friendly approach using microwave irradiation for the synthesis of zinc oxide (ZnO) nanoparticles has been reported. Zinc nitrate was used as a precursor whereas starch and D-glucose were used as capping and reducing agent, respectively. The synthesized nanoparticles were characterized by different instrumental methods including Ultraviolet-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and field emission scanning electron microscopy (FE-SEM). The characteristic λmax at 373 nm for ZnO nanoparticles was recorded from UV-Vis absorption spectrum in aqueous system. FT-IR spectrum showed a very sharp peak at 476.62 cm-1 which confirmed the presence of Zn-O bond. The prepared ZnO was highly crystalline having wurtzite structure and the crystallite size was calculated to be 24.41 nm obtained from XRD analysis. FE-SEM images showed that the synthesized ZnO nanoparticles had near- spherical morphology and particle size was found in the range of 40–90 nm. The antibacterial and anti-biofilm application of ZnO nanoparticles were studied and inhibition zones of Gram negative Salmonella typhi (S. typhi), Klebsiella spp., Escherichia coli (E. coli) and Gram positive Staphylococcus aureus (S. aureus)- 8a were found to be 11 mm, 12 mm, 11.5 mm and 13.5 mm, respectively. Besides, ZnO nanoparticles also showed excellent photocatalytic activity against methylene blue dye solution. The easy and eco-friendly fabrication method would play vital role in other nanoparticles synthesis to meet the demand in textile industry, agriculture and medical sectors.

Zinc oxide nanoparticles can be classified as a multipurpose material, along with their distinctive features and applications in optoelectronic devices. This research looks at the morphological, structural, and optical features of zinc oxide (ZnO) nanoparticles. The sol-gel procedure has been used to form zinc oxide nanoparticles with zinc nitrate [Zn (NO3)2.4H2O] and sodium hydroxide [NaOH] as precursors. The main objective is to synthesize zinc oxide (ZnO) nanoparticles by using the sol-gel approach because that is easy to implement and offers the capacity to adjust particle size and morphology by systematically monitoring reaction conditions. X-ray diffraction phenomenon, Scanning Electron Microscopy, and Ultraviolet-vis spectroscopy characterization techniques were used to determine the structural, morphological, and optical features of produced zinc oxide nanoparticles. According to the XRD examination, the produced nanoparticles are in a highly crystalline phase nature. The high crystallinity of ZnO is observed in all diffraction peaks, implying that Zinc oxide nanoparticles were synthesized properly using the sol-gel process. The UV-vis spectroscopy produced an absorption spectrum at 370nm due to ZnO nanoparticles. The Scanning Electron Microscopy (SEM) measurements reveal the surface structure and grains size of zinc oxide (ZnO) nanoparticles at a different resolution.

Many fungal endophytes were identified and evaluated for this capacity to find a potentially simple and ecologically acceptable method of producing a variety of nanoparticles (NPs) at a low cost and without the use of hazardous or harmful substances. In this study Zinc Oxide (ZnO) NPs have been synthesized using the filtrate of fungal endophytes isolated from Buchanania lanzan plant. The zinc acetate and the sodium hydroxide were used as the precursors and the fungal filtrate was used as a solvent (reducing agent) to synthesize the ZnO NPs by utilizing the sol-gel method. The biologically synthesized nanoparticles were initially monitored by ultraviolet-visible (UV-Vis) spectroscopy which shows a single plasmon resonance peak of ZnO identified within the 350-400nm range. Further, as-synthesized ZnO NPs were characterized by the x-ray diffraction (XRD), scanning electron microscopy (SEM), and the transmission electron microscopy (TEM) in imaging and diffraction mode. The morphological feature of the ZnO NPs has been analyzed and it was observed that the majority of them are spherical nanoparticles with an average particle size of 17nm, however, few ZnO nano rods were also observed. The selected area electron diffraction (SAED) analysis confirmed the pure synthesized ZnO NPs having hexagonal wurtzite phase with lattice parameters a = b = 3.24Å and c = 5.20Å. According to the results of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and total antioxidant capacity it was found that the synthesized ZnO NPs are very stable and had greater antioxidant activity than the endophytic fungal filtrate. ZnO NPs also exhibited excellent antimicrobial activity with an average inhibition zone of 18mm ( Escherichia coli), 12mm ( Pseudomonas aeuroginosa), 10mm ( Klebsiella sp.), and 6mm ( Staphylococcus aureus).

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.

Nanoparticles (NPs) exhibit distinct features compared to traditional physico-chemical synthesis and they have many applications in a wide range of fields of life sciences such as surface coating agents, catalysts, food packaging, corrosion protection, environmental remediation, electronics, biomedical and antimicrobial. Green-synthesized metal NPs, mainly from plant sources, have gained a lot of attention due to their intrinsic characteristics like eco-friendliness, rapidity and cost-effectiveness. In this study, zinc oxide (ZnO) NPs have been synthesized employing an aqueous leaf extract of Pelargonium odoratissimum (L.) as a reducing agent; subsequently, the biosynthesized ZnO NPs were characterized by ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). Moreover, aqueous plant leaf extract was subjected to both qualitative and quantitative analysis. Antioxidant activity of ZnO NPs was assessed by DPPH assay, with varying concentrations of ZnO NPs, which revealed scavenging activity with IC50 = 28.11 μg mL−1. Furthermore, the anti-bacterial efficacy of the green synthesized ZnO NPs against four foodborne pathogenic bacterial strains was examined using the disk diffusion assay, and Staphylococcus aureus (ATCC 8095), Pseudomonas aeruginosa (ATCC10662) and Escherichia coli (ATCC 25922) were found to be the most sensitive against biosynthesized ZnO NPs, whereas the least sensitivity was shown by Bacillus cereus (ATCC 13753). The anti-inflammatory effect was also evaluated for both ZnO NPs and the aqueous leaf extract of P. odoratissimum through the human red blood cells (HRBC) membrane stabilization method (MSM) in vitro models which includes hypotonicity-induced hemolysis. A maximum membrane stabilization of ZnO NPs was found to be 95.6% at a dose of 1000 μg mL−1 compared with the standard indomethacin. The results demonstrated that leaf extract of P. odoratissimum is suitable for synthesizing ZnO NPs, with antioxidant, antibacterial as well as superior anti-inflammatory activity by improving the membrane stability of lysosome cells, which have physiological properties similar to erythrocyte membrane cells and have no hemolytic activity. Overall, this study provides biosynthesized ZnO NPs that can be used as a safe alternative to synthetic substances as well as a potential candidate for antioxidants, antibacterial and anti-inflammatory uses in the biomedical and pharmaceutical industries.

The number of studies on Zinc oxide (ZnO) have increased tremendously over the last ten years due to its widespread applicability as optoelectronic device, sensor, catalyst, transparent conductive oxide layer (TCO) in solar cells and piezoelectric device. The potential compliance of ZnO in those various field is due to its unique properties which exhibit direct wide band gap (∼ 3.37 eV) semiconductor, large exciton binding energy (60 meV), possess good piezoelectric characteristics, chemical stability as well as biocompatibility. At nanometer scale, ZnO nanostructures such as nanorod, nanoneedle, nanobelt and nanoparticles have shown to exhibit different properties from the bulk. Likewise, they demonstrated significance enhancement of ZnO performance due to high surface to volume ratio characteristics. Among the various structures, ZnO nanoparticles offers great extent of applications ranging from chemical sensor, catalyst, anti-bacterial activities, transparent UV protection film, bio-imaging to bio medical application. However, the overall cost of producing these devices is relatively high compared to Si due to high cost of producing ZnO nanoparticles. Realizing of the advance functional device that ZnO nanoparticle is capable of, it is crucial to devise a method to synthesize ZnO nanoparticles for mass production. Up to now, a variety of techniques have been employed for the synthesis of ZnO nanoparticles via physical vapor deposition (PVD) and solution based method. PVD techniques, such as spray pyrolysis, sputter deposition, template assisted growth and chemical vapor deposition requires very complicated equipment, expensive raw materials, high temperature, high pressure and long deposition times which suggest that they are not suitable for large scale production at relatively low cost. In contrast to PVD, solution based techniques such as sol-gel, hydrothermal, sonochemical, microemulsion and precipitation are more feasible to be industrialized as they are low cost and produce high output volume. Comparing both physical and chemical techniques, the latter method is favored in this study. In solution technique, the selection of reactants is crucial as they are involved in the construction and formation of the particles. Most of the reagents employed for synthesizing ZnO nanoparticles are in zinc salt substance which will react with basic solution to provide a medium for nucleation and growth. Zinc salt commonly used are zinc acetate, zinc nitrate, zinc sulphate, and zinc chloride whereas for basic solution; sodium hydroxide, ammonium hydroxide, ammonium carbonate are the reagents that commonly employed. Only a few works that used elementary elements as the reactant in ZnO synthesis have been reported. For example, C. Wang and co-workers have synthesized ZnO nanoparticles using Zn and I 2 which they have discovered that I 2 plays some part in the nucleation of ZnO nanoparticles. However, the role of I 2 in ZnO formation is not thoroughly analyzed and discussed [1]. In this work, we present the study of I 2 role and improvement in ZnO nanoparticles synthesis by introducing Diethanolamine (DEA) as initiator and capping agent as well as O 2 diffusion as catalyst during nanoparticles formation. Moreover, we employed post-heat treatment to removes the byproduct. ZnO nanoparticles properties (structural, morphology and optical) produced under different calcination temperatures at 700, 850 and 1150 °C were characterized using X-ray powder diffractometer (XRD), Scanning electron microscope (SEM) and room temperature Photoluminescence (PL) spectroscopy. Based on the SEM results, uniformly spherical particles are observed for all the samples prepared in the presence of I 2 whereas microsphere with honey comb like structure were observed for samples without the presence of I 2 . Samples heated at 850°C prepared in the I 2 existence shows high intensity of blue-violet emission at 411 nm whereas sample without I 2 exhibit two emission peak centered at 380 nm (UV emission) and 523nm (green emission). Possible reason of the red shifted peak for samples prepared with I 2 with respect to UV may be attributed to zinc interstitial or zinc vacancy defects created via interaction with I 2 during nanoparticles formation. Weight % calculated for samples synthesized with I 2 is ∼ 1.795% whereas without I 2 is ∼ 0.9% indicating enhancement in terms of output volume.

In this study, Zinc oxide (ZnO) nanoparticles were prepared using Zinc nitrate (Zn(NO3)2) and Ammonium carbonate ((NH4)2CO3) in aqueous solutions with proper concentration by a direct precipitation method. The properties of ZnO nanoparticles synthesized were characterized by the thermal gravimetric (TG) and differential thermal gravimetric (DTG), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM), respectively. Both TG and DTG curves of the precursor precipitates show that no further mass loss and thermal effect were observed above the temperature 450°C. The FT-IR results indicated that the precursor of ZnO nanoparticles was zinc hydroxy carbonate. The XRD results show that the prepared ZnO nanoparticles were pure wurtzite structures. TEM photographs demonstrated that ZnO nanoparticles were of a pseudo-spherical shape with an average crystal size of about 65 nm.

In this paper, the synthesis and characterisation of ZnO nanoparticles have been carried out for textiles applications. The ZnO nanoparticles have been synthesized by precipitation method. This technique is based on precipitation procedure by using zinc nitrate and sodium hydroxide as precursors. The scanning electron microscopy, dynamic light scattering, UV-Visible spectrophotometry and X-ray diffraction were used to characterize the particle size and morphology. The synthesized ZnO nanoparticles were spherical with the size in the range of 200-400 nm. Next step, the ZnO nanoparticles were directly applied on to the fabric using pad-dry-cure method. Finally, the antibacterial efficiency of modified fabrics was quantitatively evaluated and compared against gram-negative Escherichia coli and aerobic gram-positive Staphylococcus aureusaccording to AATCC 147. The results showed that the modified fabric demonstrated significant antibacterial activity against Escherichia coli and Staphylococcus aureus. These results suggest that synthesized ZnO nanoparticles could be used effectively for textiles applications.

Synthesis and characterization of ZnO nanoparticles for photocatalysis, antibacterial and cytotoxicity in kidney cancer (A498) cell lines

Zinc Oxide Nanoparticles (ZnONPs) are one of the most widely used metal oxide nanoparticles in biological applications because of their outstanding biocompatibility, affordability, and low toxicity. In biomedicine, ZnONPs have shown promise, particularly in the disciplines of anticancer and antibacterial fields. In comparison to other standard synthesis methods, the environmentally-friendly synthesis of metallic nanoparticles utilizing various plant extracts is a good option. The current research focuses on the synthesis of zinc oxide nanoparticles (ZnONPs) from R. sativus leaf extract under various physical conditions (Precipitation method). Analytical methods were used to confirm and characterize the produced ZnONPs. The spherical nature of the produced nanoparticles was established by SEM analysis. The generation of very pure ZnONPs was confirmed by EDS data. The crystalline nature of the produced nanoparticles, with a particle size of 66.47 nm, was confirmed by XRD. The XRD graphs’ presence of the (100), (002), and (101) planes strongly suggest the production of wurtzite ZnO. The visual and infrared area exhibits transmissions of 84 percent in the pH 10 nanoparticles. The band gap of the nanoparticles increases from 3.34 to 3.38 eV when the pH increases. These nanoparticles were effective against both Gram-positive and Gram-negative bacteria. The effect of several process parameters such as pH and temperature were investigated, and the best conditions were discovered to be pH 12 and 80 °C, respectively. The effect of ZnONPs was tested with human breast cancer cells (MCF-7), and they showed significant cytotoxic results. Collectively, our data suggest that ZnONPs of R. sativus leaf extract inhibit breast cancer cell lines. The ZnONPs are, therefore, a prospective source of chemopreventive drugs that merit additional exploration in order to uncover lead compounds with cancer chemotherapeutic potential.

Synthesis and characterization of ZnO nanoparticles in n-hexanol solution

Green synthesis and characterization of zinc oxide nanoparticles with antibacterial and antifungal activity

Zinc oxide (ZnO) nanoparticles have been prepared using a pulsed electrical discharge in a liquid medium. The effects of the processing parameters, including liquid media, current, frequency of the electrical discharge and electrode gap distance exert significant effects on the characteristic and properties of ZnO nanoparticles. The synthesized ZnO nanoparticles are characterized using a combination of transmission electron microscopy (TEM), energy dispersive X-ray (EDS) and photoluminescence (PL) spectroscopy. The average size of ZnO nanoparticles varies between 10–25 nm depending on the processing parameters. It is found that an increase in the arc current plays a great role in particle growth and results in a significant increase in average particles size. Both frequency of discharge and electrode gap distance can influence the average particle size and distribution due to the variation in the cooling rate. The PL spectrum for all as-synthesized ZnO nanoparticles exhibits an ultraviolet emission (~3.4 eV) and a red visible emission (~1.98 eV). The blue shift is independent of the average size of the ZnO nanoparticles. However, the intensity of visible emission is significantly enhanced with the decrease of the particle sizes. The porous structure and irregular particle surface are suggested to contribute significantly to the visible red emission.