Nano-sized Zinc Oxide Particles Research Articles

Enhancing Hydrogen Sulfide Gas Detection: Tailoring ZnO Films Through a Novel Sol–Gel Approach with Ultra-Sonication

In this study, nano-sized Zinc Oxide (ZnO) particles were synthesized using a novel sol–gel process with Zn(NO3)2 solutions, specifically tailored for the development of a highly efficient Hydrogen Sulphide (H2S) gas sensing element. The impact of ultra-sonication on the properties crucial for H2S detection was systematically investigated. The resulting ZnO materials exhibited a well-defined crystalline structure along (100), (002), (101), and (102) planes, confirming the formation of the hexagonal wurtzite phase of ZnO. Significantly, an increase in sonication treatment time led to a reduction in particle size. The gas sensing properties for H2S were meticulously analyzed in relation to the varying sizes of ZnO films. Remarkably, the ZnO film fabricated with a 30-minute ultra-sonication treatment demonstrated the highest response to H2S gas at 423 K. The ZnO-thick films exhibited notable sensitivity, coupled with rapid reactivity and recovery times upon exposure to H2S gas. Importantly, our findings establish a direct correlation between the sensitivity of the ZnO sensor and the particle size.

Nanotechnology's Application in Cosmetics: Dermatology and Skin Care Items

Nanotechnology has emerged as a revolutionary force in various fields, and its application in cosmetics has significantly transformed the landscape of dermatology and skin care. This abstract explores the multifaceted impact of nanotechnology on cosmetic products, focusing on its potential to enhance efficacy, improve delivery systems, and address specific dermatological concerns. Integrating nanotechnology into cosmetics offers a notable advantage by enabling precise control of materials at the nanoscale. This capability leads to the creation of formulations that exhibit enhanced bioavailability. The use of nano-sized particles, typically measured in nanometers, improves the penetration of active ingredients into the skin, ensuring precise delivery and increased absorption. This precision has paved the way for the development of highly effective skincare products capable of addressing specific skin conditions such as hyperpigmentation, fine lines, and acne. Furthermore, nanotechnology has revolutionized the formulation of sunscreens, offering transparent and cosmetically elegant options that provide superior protection against both UVA and UVB rays. Nano-sized titanium dioxide and zinc oxide particles scatter light more effectively, offering broad-spectrum coverage without the white residue associated with traditional sunscreens. Enhanced visual appeal motivates consistent application of sunscreen, fostering improved skin well-being and diminishing the likelihood of skin damage caused by sun exposure. In the realm of dermatology, nanotechnology has played a pivotal role in propelling forward groundbreaking therapeutic strategies. Nanoparticles are utilized to encapsulate and transport active components, including vitamins and antioxidants, ensuring their stability and prolonged release. This targeted approach allows for the customization of skincare regimens based on individual skin needs, thereby optimizing treatment outcomes for various dermatological conditions. Despite the remarkable advancements facilitated by nanotechnology, concerns have been raised regarding the safety of nano-sized particles in cosmetics. Addressing these concerns is crucial to ensure consumer confidence and regulatory compliance. Thorough testing and extensive research are crucial for a comprehensive evaluation of the safety characteristics of nanomaterials, taking into account factors such as particle size, surface charge, and potential interactions with the skin. In summary, the integration of nanotechnology into cosmetics marks a new era of innovation in dermatology and skincare. It not only enhances the delivery of active ingredients but also improves the effectiveness of sunscreens, presenting a promising path for the advancement of cutting-edge cosmetic formulations. As research in this field advances, it is essential to find a balance between innovation and safety, ensuring that nanotechnology continues to positively influence the cosmetics industry while prioritizing the well-being of consumers.

Photocurrent performance and enhancement of opto-electronic properties of spray pyrolysis deposited ZnO thin films via V-doping

This study reports on the deposition of highly transparent conducting n-type zinc oxide (ZnO) thin films on FTO substrates, via an optimized doping process. Our work is focused on doping zinc oxide with vanadium (V) using spray pyrolysis technique and ensure the synthesis of nanoparticles-shaped ZnO, with an improved optical, microstructural and electrical properties for solar cells applications, as optical window material. Undoped and V-doped ZnO thin films, with careful optimized amounts (2, 4, 6 and 8 at.%), were grown at maintained 550∘C pre-heated substrate during the deposition process, which enables us to obtain nano-sized ZnO particles. We proved that 4 at.% is the optimum V content that enhances the crystallinity of the grown thin film noticeably. With an average transmittance of 80%, the deposited thin films revealed high transparency in the visible domain with a slight decrease in optical transmission which might result from additional scattering. UV-Visible analysis showed that increasing V amounts, a resulting decrease in the energy bandgap ([Formula: see text]) is obtained from 3.26[Formula: see text]eV to 3.17[Formula: see text]eV for 4 at.% of V content. Moreover, deep level defects in zinc oxide can be reduced with vanadium doping and consequently strengthen the UV emission. The UV emission peak intensity rises with increasing V-doping amount then decreases slightly at 8% of V content. The electrical properties measurements showed a decrease in resistivity from 2.8 10[Formula: see text][Formula: see text][Formula: see text][Formula: see text]⋅[Formula: see text]cm to 0.9 10[Formula: see text][Formula: see text][Formula: see text][Formula: see text]⋅[Formula: see text]cm when doping with 4 at.% of V. The crucial effect of the V-doping of ZnO was also demonstrated via the enhancement of carrier mobility that attains 38.5[Formula: see text]cm2/V[Formula: see text]⋅[Formula: see text]s at the optimum vanadium content. The photocurrent analysis revealed much higher visible light absorption in the V-doped zinc oxide thin films than that of undoped film. The photocatalytic activity enhancements are attributed to the lower recombination rate of the photogenerated electron-hole pairs, the narrowed bandgap, yielding a higher photocatalytic performance.

Electrocatalytic and photocatalytic activities of hierarchically structured zinc oxide nanoparticles derived from cellulose paper-precipitated hydrozincite

This study presents a novel method for synthesizing hierarchical porous zinc oxide (ZnO) nanostructures by thermally decomposing green-synthesized hydrozincite. The hydrozincite was prepared at room temperature using zinc acetate dihydrate and calcium carbonate (CaCO3) in cellulose printing papers as the precipitating agent. The resulting ZnO particles exhibit a distinctive flower-like morphology, consisting of porous nanosheets composed of interconnected nanoparticles. The average crystallite size of the hierarchically structured zinc oxide nanoparticles, as determined via X-ray diffraction Rietveld refinement method, was found to be 18.8 nm when calcined at 500 °C. However, with increasing calcination temperature to 600, 700, and 800 °C, the average crystallite size also increased to 24.3, 30.4, and 47.2 nm, respectively. The ZnO synthesized at temperatures of 500 °C, 600 °C, and 700 °C exhibits higher electrocatalytic activity toward the hydrogen evolution reaction (HER) compared to both the ZnO synthesized at 800 °C and commercial ZnO. This enhanced performance can be primarily attributed to the nanosized ZnO particles, which provide a substantial surface area, high accessibility of active sites, and fast charge transfer kinetics. In terms of photocatalytic activity, all the samples show HER improvement under the UV light irradiation, attributed to the generation of photoexcited charge carriers. The ZnO synthesized at 800 °C and the commercial ZnO exhibit greater enhancements in photocatalytic activity compared to the other samples. This implies that larger solid particles with fewer nanopores result in a greater exposed surface area for UV-light absorption. The hierarchically structured ZnO nanoparticles demonstrate promising electrocatalytic and photocatalytic activities, as well as stability, opening up potential applications in various fields, including energy conversion and environmental remediation.

Antibacterial Properties of Borosilicate Enamel with Nanosized Zinc Oxide Particles

Antibacterial Properties of Borosilicate Enamel with Nanosized Zinc Oxide Particles

Synthesis and characterization of zinc oxide nanoparticles (ZnO-NPs) for biodiesel production using waste frying oil (WFO)

In this research, zinc oxide nanoparticles (ZnO-NPs) were synthesized by simple solution-based approach using zinc nitrate [Zn(NO3)2.6H2O] and sodium hydroxide (NaOH) as precursor. The Synthesized ZnO-NPs were characterized by XRF, XRD and TGA methods. XRD method confirmed the formation of nanosized zinc oxide particles in the size range of 13–47 nm. XRF and TGA were used to determine the elemental composition and thermal stability of ZnO-NPs, respectively. The ZnO-NPs were used as catalyst in the production of biodiesel from waste frying oil (WFO) via transesterification method. The transesterification process yielded 97.8 % (w/w) WFO biodiesel. The results of the fuel properties revealed that, all the parameters tested are within the ASTM limits, indicating that the biodiesel produced could be used as an alternative diesel fuel.

Development and Testing of Zinc Oxide Embedded Sulfonated Poly (Vinyl Alcohol) Nanocomposite Membranes for Fuel Cells

The sol-gel technique was adopted to synthesize the zinc oxide (ZnO) nanoparticles. Nano-sized ZnO particles are embedded in-situ to the poly(vinyl alcohol) (PVA) matrix to form the nanocomposite polymeric membranes. The nanocomposite membranes were fabricated by varying concentration of ZnO nanoparticles of 2.5, 5, and 10 wt.% in the base PVA membrane matrix. The membranes were crosslinked using tetraethyl orthosilicate (TEOS) followed by hydrolysis and co-condensation. Immersion in a 2 molar sulphuric acid (H2SO4) bath produced sulfonated membranes. The membranes were characterized using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). The fabricated nano-composite membranes are being evaluated for proton exchange membrane fuel cell research (PEMFC). The computed test results demonstrate that increasing the concentration of ZnO in the membrane increased the ionic exchange capacity and proton conductivity efficiency of the nano-composite membranes. The incorporation of a quantum quantity of ZnO particles in the membrane improved the presentation in terms of proton conductivity characteristics. Membranes demonstrated excellent proton conductivity (10−2 S cm−1 range) while consuming less hydrogen gas. The highest measured proton conductivity is observed for 10 wt.% ZnO embedded PVA membrane and the value is 15.321 × 10−2 S cm−1 for 100% RH. The combination of ZnO and PVA nanocomposite membrane is a novel, next-generation eco-friendly method that is economical and convenient for large-scale commercial production in fuel cell applications.

A comparative evaluation of the effects of seed invigoration treatments with precursor zinc salt and nano-sized zinc oxide (ZnO) particles on vegetative growth, grain yield, and quality characteristics of Zea mays

IntroductionThe zinc micronutrient fertilizers have a critical impact on the grain productivity and quality attributes of maize. However, the low use-efficiency issues of the applied Zn-fertilizers are required to be addressed through the development of novel formulations and alternative application techniques.ObjectivesThis field study investigates the comparative impact of seed invigoration (including seed priming and coating) treatments with bulk zinc and ZnO nanoparticles (ZnONPs).MethodsThe two seed treatments with two different zinc sources at three different concentrations of 0, 20, and 40 mg L−1 each, for a total of ten treatments, were evaluated for vegetative growth, photosynthetic pigments, grain yield, and quality traits in Zea mays.ResultsThe total chlorophyll content was improved by ZnONPs seed priming at the V8 stage. However, there were plants that grew tall, bearing longer ears with bulk ZnSO4 and the untreated control. Yield-contributing factors like number of seeds per cob, and 1000-grain weight were marginally improved by ZnONPs treatment. Overall, only cob weight, starch, total soluble protein, and soil nutrient (N, P, K, and Zn) content were significantly enhanced by ZnONPs treatment. Furthermore, no negative effect was recorded on the soil microbiological and enzymatic activities seed treatment with both the zinc sources.ConclusionThe seed treatment, i.e. coating and priming with ZnONPs, did not significantly alter the grain yield, but the seed starch and total soluble protein content were improved.

Preparing and Characterizing Novel Biodegradable Starch/PVA-Based Films with Nano-Sized Zinc-Oxide Particles for Wound-Dressing Applications

Given recent worldwide environmental concerns, biodegradability, antibacterial activity, and healing properties around the wound area are vital features that should be taken into consideration while preparing biomedical materials such as wound dressings. Some of the available wound dressings present some major disadvantages. For example, low water vapor transmission rate (WVTR), inadequate exudates absorption, and the complex and high environmental cost of the disposal/recycling processes represent such drawbacks. In this paper, starch/polyvinyl alcohol (PVA) material with inserted nano-sized zinc-oxide particles (nZnO) (average size ≤ 100 nm) was made and altered using citric acid (CA). Both ensure an efficient antibacterial environment for wound-dressing materials. The film properties were assessed by UV–Vis spectrometry and were validated against the UV light transmission percentage of the starch/ polyvinyl alcohol (PVA)/ zinc-oxide nanoparticles (nZnO) composites. Analyses were conducted using X-ray Spectroscopy (EDX) and scanning electron microscopy (SEM) to investigate the structure and surface morphology of the materials. Moreover, to validate an ideal moisture content around the wound area, which is necessary for an optimum wound-healing process, the water vapor transmission rate of the film was measured. The new starch-based materials exhibited suitable physical and chemical properties, including solubility, gel fraction, fluid absorption, biodegradability, surface morphology (scanning electron microscopy imaging), and mechanical properties. Additionally, the pH level of the starch-based/nZnO film was measured to study the prospect of bacterial growth on this wound-dressing material. Furthermore, the in vitro antibacterial activity demonstrated that the dressings material effectively inhibited the growth and penetration of bacteria (Escherichia coli, Staphylococcus aureus).

On ZnO nano particle reinforced PVDF composite materials for 3D printing of biomedical sensors

Abstract The inherent piezoelectric and biocompatibility behaviour of polyvinylidene difluoride (PVDF) and excellent biocompatibility, thermal and magnetic responses of zinc oxide (ZnO) nano particles made their blends as a good candidate for biosensor 3D printing. In this study, the co-precipitation method has been used to prepare the nano-sized ZnO particles, which are further reinforced with PVDF on twin screw compounder with the controlling proportion of ZnO, forced loading, and torque. The investigations of mechanical, thermal, morphological, and shape memory effect have been performed on the prepared feedstock filaments to check the effect of controlling parameters. It has been observed that maximum mechanical strength (tensile strength, percentage elongation and modulus of toughness) results without ZnO nano particle reinforcement, 1% reinforced critically reduced the mechanical properties but the mechanical properties of 2% ZnO nanoparticle reinforced PVDF composite were obtained better than PVDF-1%ZnO and less than PVDF-0%ZnO. Thermal analysis shows that increase in the ZnO percentage into PVDF improves the normalized heat capacity (25.16 J/g in PVDF to 33.07 J/g in PVDF-2%ZnO). The energy dispersive spectroscopy (EDS) analysis confirms the presence of ZnO on the fracture surface. The shape memory was found 98.22 % for PVDF-2%ZnO at 25 °C.

Health effects after inhalation of micro- and nano-sized zinc oxide particles in human volunteers

Inhalation of ZnO particles can cause inflammation of the airways and metal fume fever. It is unclear if different sizes of the particles alter these effects. However, various studies report higher biological activity of other nano-sized particles compared to microparticles. No effects at all were observed after inhalation of micro- and nano-sized zinc oxide (ZnO) particle concentrations of 0.5 mg/m3. Studies with different particle sizes of ZnO at higher exposures are not available. Accordingly, we hypothesized that inhalation of nano-sized ZnO particles induces stronger health effects than the inhalation of the same airborne mass concentration of micro-sized ZnO particles. 16 healthy volunteers (eight men, eight women) were exposed to filtered air and ZnO particles (2.0 mg/m3) for 2 h (one session with nano- and one with micro-sized ZnO) including 1 h of cycling at moderate workload. Effect parameters were symptoms, body temperature, inflammatory markers in blood and in induced sputum. Induced sputum was obtained at baseline examination, 22 h after exposure and at the end of the final test. The effects were assessed before, immediately after, about 22 h after, as well as two and three days after each exposure. Neutrophils, monocytes and acute-phase proteins in blood increased 22 h after micro- and nano-sized ZnO exposure. Effects were generally stronger with micro-sized ZnO particles. Parameters in induced sputum showed partial increases on the next day, but the effect strengths were not clearly attributable to particle sizes. The hypothesis that nano-sized ZnO particles induce stronger health effects than micro-sized ZnO particles was not supported by our data. The stronger systemic inflammatory responses after inhalation of micro-sized ZnO particles can be explained by the higher deposition efficiency of micro-sized ZnO particles in the respiratory tract and a substance-specific mode of action, most likely caused by the formation of zinc ions.

In situ formed zinc oxide/graphitic carbon nitride nanohybrid for the electrochemical determination of 4-nitrophenol.

The electrochemical determination of 4-nitrophenol using a nanohybrid consisting of glassy carbon (GC)and zinc oxide/graphitic carbon nitride (ZnO/g-CN nanosheet), is described. The ZnO/g-CN nanohybrid was in situ synthesized by chemical method and well characterized using absorption spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopic analysis. It was observed that the nanosized ZnO particles were present inside the sheet-like g-CN nanostructure. The nanohybrid-modified electrode showed an enhanced electrocatalytic response for 4-nitrophenol reduction compared with the bare GC electrode. The assay exhibited linear ranges of 13.4-100μM and 100-1000μM for 4-NP determination. The limit of detection and limit of quantification were 4.0 and 13.4μM, respectively, at the working potential of - 0.85V. An appreciable precision was found towards the stability of the assay in the determination. It provides selectivity against inorganic and organic substances such as calcium chloride, potassium chloride, nitrobenzene, uric acid, 1-chloro,2,4-dinitrobenzene, 1-bromo,2-nitrobenzene and 1-iodo,2-nitrobenzene. The practical applicability of the assay was also checked in the analysis ofreal water samples and satisfactory recovery of 4-NP was found. Schematic representation of the synthesis of zinc oxide (ZnO) nanostructures incorporated graphitic carbon nitride nanosheets (g-C3N4 NSs) and its application in the voltammetric determination of 4-nitrophenol (4-NP) is presented. The nanohybrid assay showed selectivity among coexisting compounds and good recovery in real sample analysis.

Synthesis and characterisation of zinc oxide catalyst and its composite with polymer additives

Nano-sized zinc oxide (ZnO) particles and its composite were synthesised with xanthan gum (XG) and carboxymethyl cellulose (CMC) polymers.This work studied different concentrations of the surface adsorption of these polymers onto the Zinc oxide (ZnO) nanoparticles.The concentrations used as mass ratio were (1:1, 1:0.5 and 1:0.25w/w) for ZnO/polymer. The nanoparticles are then analysed using scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), particle size and BET surface area.Composition of the samples was recognised with X-ray diffraction. The shape of particles changes with addition polymeric additives. It has been indicated that the low concentration polymers display a weaker effect on the surface of particles in comparison to the polymers with high concentration and CMC polymer better than XG polymer since it facilitated to produce finest nanoparticles with higher surface area.

Stability of Nano-ZnO in simulated landfill leachate containing heavy metal ions.

As the presence of nanosized zinc oxide particles (nano-ZnO) in landfill leachate increases, their interaction with coexisting heavy metal ions (HMs) also increases. The interface interaction between nano-ZnO and HMs will influence nano-ZnO stability and therefore affect its bioavailability and environmental impact. In the present study, we investigated the effects of Cu(II), Cr(III), and Cr(VI) ions on the aggregation, sedimentation, and dissolution of nano-ZnO using batch experiments with a view to better understanding their co-effect on the environment. Dynamic light scattering and UV-Vis spectroscopy results show enhanced aggregation of nano-ZnO in the presence of Cr(VI) ions under fresh landfill leachate conditions, in addition to distinct sedimentation of nano-ZnO in the presence of Cr(III) ions in both fresh and aged landfill leachate. In fresh leachate, Cu(II) ions improved the concentration of dissolved Zn from nano-ZnO. However, the effects of Cu(II), Cr(III), and Cr(VI) ions on the aggregation and dissolution of nano-ZnO were markedly reduced in aged landfill leachate. Both acetic and humic acids in landfill leachate significantly affected the stability of nano-ZnO in the presence of HMs. According to the ATR-FTIR results, Cr(III) ions reacted with hydroxyl groups on nano-ZnO to form ZnO-O bonds, which induced chains of nano-ZnO and Cr(III) complexes, and hence the increased of nano-ZnO aggregates. ATR-FTIR shows merely electrostatic adsorption effects between nano-ZnO and Cu(II) or Cr(VI) ions. In brief, the mode of interactions between HMs and nano-ZnO influenced the stability via adsorption and binding effects. The results of the present research provide insight into the potential effects of nano-ZnO on the environment in the presence of HMs in landfill leachate.

Whole Blood Assay as a Tool to Describe the Effects of Zinc Oxide Exposure on Innate Immunity.

Inhalation of high concentrations of zinc oxide (ZnO) particles may cause metal fume fever. A useful tool to characterize the reactivity of innate immune cells of an individual, e.g., after in vivo exposure, is the whole blood assay (WBA). The measurable outcome of WBA is the release of cytokines, especially pro-inflammatory and pyrogenic cytokines induced by stimulation in vitro. The aim of the study was to evaluate whether inhalation of nano-sized zinc oxide particles modifies the results of WBA from healthy blood donors. Sixteen healthy subjects were exposed to filtered air and ZnO particles (0.5, 1.0, and 2.0mg/m3) for 4h on four different days. Blood was collected before and 24h after exposure, and ex vivo stimulation of the whole blood was performed using different endotoxin concentrations. The release of interleukin (IL)-1β and IL-8 after 22-h incubation was quantified with specific immunoassays. The dose-response relationship of ex vivo stimulation with different endotoxin concentrations was not affected by previous ZnO exposure. However, based on the previously established calculation models, changes due to ZnO exposure could be described. The range of cytokine release in WBA was calculated for the whole group of blood donors, for the subgroups of low and high responders (each n=8), and on the individual level. Most changes were observed after 0.5mg/m3 ZnO exposure. Higher ZnO exposure did not yield higher effects. We conclude that the effects of inhalation of nano-sized ZnO particles in blood of healthy donors using the WBA could be determined. However, it should be noted that cytokine release as outcome of WBA is not a marker of disease.

Airway inflammation after inhalation of nano-sized zinc oxide particles in human volunteers

BackgroundWorkers in the zinc production and processing of galvanized sheet steel are exposed to a complex mixture of particles and gases, including zinc oxide (ZnO) that can affect human health. We aimed to study the effects of short-term controlled exposure to nano-sized ZnO on airway inflammatory markers in healthy volunteers.MethodsSixteen subjects (8 females, 8 men; age 19–42, non-smokers) were exposed to filtered air and ZnO nanoparticles (0.5, 1.0 and 2.0 mg/m3) for 4 h, including 2 h of cycling with a low workload. Induced sputum samples were collected during a medical baseline and a final examination and also about 24 h after each exposure. A number of inflammatory cellular and soluble markers were analyzed.ResultsFrequency and intensity of symptoms of airway irritation (throat irritation and cough) were increased in some subjects 24 h after ZnO exposures when compared to filtered air. The group comparison between filtered air and ZnO exposures showed statistically significant increases of neutrophils and interleukin-8 (IL-8), interleukin-6 (IL-6), matrix metalloproteinase (MMP-9) and tissue inhibitors of metalloproteinases (TIMP-1) in sputum starting at the lowest ZnO concentration of 0.5 mg/m3. However, a concentration-response relationship was absent. Effects were reversible. Strong correlations were found between neutrophil numbers and concentrations of total protein, IL-8, MMP-9, and TIMP-1.ConclusionsControlled exposures of healthy subjects to ZnO nanoparticles induce reversible airway inflammation which was observed at a concentration of 0.5 mg/m3 and higher. The lack of a concentration-response relationship warrants further studies.

Green Synthesis of ZnO Nano Particles Using Chlorella vulgaris Extract as Additives

The application of nano zinc oxide in health-related fields calls for green and environmentally friendly synthetic methods. In this paper, Chlorella vulgaris extract was used to synthesize uniform nano sized zinc oxide particles. The results indicate that Chlorella vulgaris extract can effectively reduce the size of zinc oxide particles. The as synthesized ZnO particles using Chlorella vulgaris extract as additive are about 20-40nm.

Synthesis of eco-friendly facile nano-sized zinc oxide particles using aqueous extract of Cymodocea serrulata and its potential biological applications

Green synthesis of nanoparticles is an emerging branch of nanotechnology due to its low cost and effectiveness. In this study, zinc oxide (ZnO-NPs) nanoparticles were biosynthesized by an eco-friendly method using Cymodocea serrulata. They were characterized by Ultraviolet–visible (UV–vis) spectroscopy, energy-dispersive X-ray (EDX), scanning electron microscopy (SEM), X-ray diffractometer (XRD), atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy. The synthesized crystalline nanoparticles were found to be 26.0–52.0 nm in size. The antioxidant activity of synthesized ZnO nanoparticles at 1000 µg/ml have revealed 75.55% in DPPH, 69.5% in deoxy-ribose, 62.75% in ABTS, 71.25% in nitric oxide and 74.10% in superoxide-scavenging assays. They also depicted significant bactericidal action against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, and Shigella flexneri. ZnO nanoparticles at 100 µg/ml concentration showed increased inhibition against B. subtilis with 18.0 mm, whereas moderate inhibition was seen against S. flexneri with 14.3 ± 0.25 mm. The cytotoxicity of ZnO-NPs was evaluated on A549 and H520 cell lines. The anti-proliferative effect was seen at 120 µg concentration on A549 and H520 cell lines with IC50 values of 55.0 ± 0.25 and 60.0 ± 0.50 µg/ml at 24 h. C. serrulata-coated zinc nanoparticles was found potential against bacterial pathogens and cancer cells. Therefore, they may be developed in future for biomedical applications.

Antibacterial activity of ZnO nanoparticles: dependence on particle size, dispersion media and storage time

Zinc oxide nanoparticles have a high potential as novel antimicrobial products. In this study ZnO nanoparticles of various sizes: 20-100 nm (ZnO-1) and 50-300 nm (ZnO-2) have been examined. This paper presents the results of an integrated study of the influence of physicochemical properties such as particle size and concentration of the freshly prepared and 24-hour suspensions of ZnO nanoparticles (0. 001…1000 mg/L) in distilled water and in normal saline upon their toxicity against bacteria E. coli. Ionic solutions of ZnCl2 were used for comparison study. Fresh aqueous solutions of nanoparticles displayed the highest antibacterial effect (E. coli survival under 5 − 25%). Storage for 24 hours reduced the toxicity of all the samples. In normal saline solutions the toxicity of the studied nanoparticles decreased at concentrations below 10 g/L. In all cases ZnO-2 suspensions displayed lower toxicity levels, especially after ageing for 24 hours. Stability analysis showed that the highest antibacterial effect was produced by less stable solutions containing the largest aggregates. Thus, it has been shown that antibacterial effects of zinc oxide nanoparticles are affected by the size of particles and their aggregates in colloidal solutions, chemical composition of the media and the suspensions storage time. The obtained results can be used for creating new types of antibacterial products including phytoprotectors based on nano-sized zinc oxide particles as well as for development of methods to assess and predict toxicity of zinc-containing suspensions.

Development and evaluation of diffusive gradients in thin films based on nano-sized zinc oxide particles for the in situ sampling of tetracyclines in pig breeding wastewater

The pollution of antibiotics, including tetracyclines (TCs), in aquatic environments has become an issue of concern in recent years. Herein, an in situ sampling of TCs in pig breeding wastewater that utilizes the technique of diffusive gradients in thin films (DGT), based on commercial nanosized ZnO (nanoZnO) particles as the potential effective binding agent and a polyethersulfone (PES) membrane as the diffusion layer, was developed. The diffusion coefficients of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) in a PES membrane at 25 °C were (1.37 ± 0.06) × 10−6 cm2 s−1, (1.29 ± 0.05) × 10−6 cm2 s−1 and (1.94 ± 0.07) × 10−6 cm2 s−1, respectively. The results showed that the adsorption capacities of a gel disc containing 2.5 g L−1 of nanoZnO particles were as high as 3.93 ± 0.20 mg disc−1 for TC, 3.21 ± 0.20 mg disc−1 for OTC and 4.62 ± 0.22 mg disc−1 for CTC. Both a solution pH in the range of 5–9 and an ionic strength (as pNaCl) in the range of 1–3 had an insignificant influence on the TCs uptake by nanoZnO−DGT samplers. There was no significant influence of fulvic acid or tannic acid on the TC uptake by nanoZnO−DGT samplers at the tested mass ratios. For all spiked freshwater samples, there was no notable interference of matrices on the performance of the nanoZnO−DGT samplers, suggesting that the nanoZnO−DGT samplers yielded satisfactory results for the uptake of TCs at concentrations existing in the spiked freshwater samples. Field deployment of the nanoZnO−DGT samplers in pig breeding wastewater also exhibited excellent precision and accuracy, indicating that the nanoZnO−DGT samplers could be used as a promising method for the in situ sampling of TC antibiotics in aquatic environments.