Different Concentrations Of Zinc Oxide Nanoparticles Research Articles

Synthesis of green zinc-oxide nanoparticles and its dose-dependent beneficial effect on spermatozoa during preservation: sperm functional integrity, fertility and antimicrobial activity.

Introduction: The development of an effective extender is important for semen preservation and the artificial insemination (AI) industry. This study demonstrates the beneficial effect of zinc oxide nanoparticles (ZnO-NPs) as an additive to semen extenders to improve semen quality, fertility, and antibacterial activity during liquid preservation in a boar model. Methods: Initially, to find out the safe concentration of ZnO-NPs in sperm cells, a wide range of ZnO-NP concentrations (0, 5, 10, 50, 100, 500, and 1,000μM) were co-incubated with sperm at 37°C for a cytotoxic study. These NP concentrations were compared to their salt control zinc acetate (ZA) at the same concentrations and to a control group. The effect of the different concentrations of ZnO-NPs on sperm motility, membrane integrity, mitochondrial membrane potential (MMP), and apoptosis was assessed. Accordingly, the non-toxic dose was selected and supplemented in MODENA extender to determine its beneficial effect on the boar semen parameters mentioned and the lipid peroxidation (LPO) levels during liquid preservation at 16°C for 6days. The non-cytotoxic dosage was subsequently chosen for AI, fertility investigations, and the evaluation of the antibacterial efficacy of ZnO-NPs during preservation hours. An antibacterial study of ZnO-NPs and its salt control at doses of 10μM and 50μM was carried out by the colony forming unit (CFU) method. Results and discussion: The cytotoxic study revealed that 5, 10, and 50μM of ZnO-NPs are safe. Consequently, semen preserved in the MODENA extender, incorporating the non-toxic dose, exhibited 10 and 50μM ZnO-NPs as the optimal concentrations for beneficial outcomes during liquid preservation at 16°C. ZnO-NPs of 10μM concentration resulted in a significantly (p < 0.05) improved conception rate of 86.95% compared to the control of 73.13%. ZnO-NPs of 10 and 50μM concentrations exhibit potent antimicrobial action by reducing the number of colonies formed with days of preservation in comparison to the negative control. The investigation concluded that the incorporation of 10μM ZnO-NPs led to enhancements in sperm motility, membrane integrity, and MMP, attributed to a reduction in the malondialdehyde (MDA) levels. This improvement was accompanied by a concurrent increase in fertility rates, including farrowing rate and litter size, during the liquid preservation process. Furthermore, ZnO-NPs exhibited an antimicrobial effect, resulting in decreased bacterial growth while preserving boar semen at 16°C for 6days. These findings suggest that ZnO-NPs could serve as a viable alternative to antibiotics, potentially mitigating antibiotic resistance concerns within the food chain.

Exposure to zinc oxide nanoparticles induced reproductive toxicities in male Sprague Dawley rats

BackgroundThis research delves into the reproductive toxicology of zinc oxide nanoparticles (ZnO-NPs) in male Sprague Dawley rats. It specifically examines the repercussions of Zn accumulation in the testes, alterations in testosterone levels, and histopathological changes in the gonadal tissues. AimsThe primary objective of this study is to elucidate the extent of reproductive toxicity induced by ZnO-NPs in male Sprague Dawley rats. The investigation aims to contribute to a deeper understanding of the potential endocrine and reproductive disruptions caused by ZnO-NPs exposure. MethodsCharacterization techniques including SEM-EDX and XRD affirmed the characteristic nature of ZnO-NPs. Twenty-five healthy post weaning rats (200–250 g) were intraperitoneally exposed to different concentrations of ZnO-NPs @ 10 or 20 or 30 mg/kg BW for 28 days on alternate days. ResultsResults showed significant dose dependent decline in the body weight and testicular somatic index of rats. It also showed significant dose dependent accumulation of Zn in testis with increasing dose of ZnO-NPs. Conversely, serum testosterone level and sperm count were reduced with increasing dose of ZnO-NPs. Histological results showed dose dependent abnormalities i.e., vacuolization, edema, hemorrhage, destruction of seminiferous tubules, loss of germ cells and necrosis in rat testis. ConclusionThe findings of this study clearly indicate that high doses of zinc oxide nanoparticles (ZnO-NPs) can adversely affect the structural integrity and functional efficacy of the male reproductive system. Given these results, it becomes crucial to implement stringent precautionary measures in the utilization of ZnO-NPs, particularly in cosmetics and other relevant sectors. Such measures are imperative to mitigate the toxicological impact of ZnO-NPs on the male reproductive system and potentially on other related physiological functions. This study underscores the need for regulatory vigilance and safety assessments in the application of nanotechnology to safeguard human health.

Effects of Zinc Oxide Nanoparticles on Growth, Development, and Flavonoid Synthesis in Ginkgo biloba

Ginkgo biloba is a highly valuable medicinal plant known for its rich secondary metabolites, including flavonoids. Zinc oxide nanoparticles (ZnO-NPs) can be used as nanofertilizers and nano-growth regulators to promote plant growth and development. However, little is known about the effects of ZnO-NPs on flavonoids in G. biloba. In this study, G. biloba was treated with different concentrations of ZnO-NPs (25, 50, 100 mg/L), and it was found that 25 mg/L of ZnO-NPs enhanced G. biloba fresh weight, dry weight, zinc content, and flavonoids, while 50 and 100 mg/L had an inhibitory effect on plant growth. Furthermore, quantitative reverse transcription (qRT)-PCR revealed that the increased total flavonoids and flavonols were mainly due to the promotion of the expression of flavonol structural genes such as GbF3H, GbF3′H, and GbFLS. Additionally, when the GbF3H gene was overexpressed in tobacco and G. biloba calli, an increase in total flavonoid content was observed. These findings indicate that 25 mg/L of ZnO-NPs play a crucial role in G. biloba growth and the accumulation of flavonoids, which can potentially promote the yield and quality of G. biloba in production.

Effects of Zinc Oxide Particles with Different Sizes on Root Development in Oryza sativa

Given the consistent release of zinc oxide (ZnO) nanoparticles into the environment, it is urgent to study their impact on plants in depth. In this study, grains of rice were treated with two different concentrations of ZnO nanoparticles (NP-ZnO, 10 and 100 mg/L), and their bulk counterpart (B-ZnO) were used to evaluate whether ZnO action could depend on particle size. To test this hypothesis, root growth and development assessment, oxidative stress parameters, indole-3-acetic acid (IAA) content and molecules/enzymes involved in IAA metabolism were analyzed. In situ localization of Zn in control and treated roots was also performed. Though Zn was visible inside root cells only following nanoparticle treatment, both materials (NP-ZnO and B-ZnO) were able to affect seedling growth and root morphology, with alteration in the concentration/pattern of localization of oxidative stress markers and with a different action depending on particle size. In addition, only ZnO supplied as bulk material induced a significant increase in both IAA concentration and lateral root density, supporting our hypothesis that bulk particles might enhance lateral root development through the rise of IAA concentration. Apparently, IAA concentration was influenced more by the activity of the catabolic peroxidases than by the protective action of phenols.

Antioxidant effects of zinc-oxide nanoparticles on post-thaw quality and in vivo fertility of Beetal buck spermatozoa

Metallic nanoparticles are generally considered potential cryoprotectants during semen cryopreservation owing to their ability to improve the spermatozoa quality following cryopreservation when added in cryo-diluents. The present study aimed at investigating the effects of incorporating zinc oxide nanoparticles (ZnO-NPs) in the cryo-diluent on in vitro post-thaw sperm quality attributes, oxidant-antioxidant profile, and in vivo fertility rate in Beetal buck. After characterization, ZnO-NPs were added to the Tris-citric acid-fructose yolk extender. Semen samples, collected from five breeding bucks (5 ejaculates per buck) using an artificial vagina, were pooled. The pooled semen samples, distributed into five equal aliquots, were diluted in the Tris-citric acid cryo-diluent containing five different concentrations of ZnO-NPs (0.5 mg/ml, 1.0 mg/ml, 1.5 mg/ml, 2.0 mg/ml, and 0.0 mg/ml called control group), and were cryopreserved for 24 h. At post-thaw, various in vitro sperm quality parameters, and antioxidant enzyme profiles like superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and reduced glutathione (GSH) levels were determined. For the in vivo fertility experiment, breeding does (n = 152), aging from 1.5 to 4 years, were artificially inseminated with spermatozoa with intact acrosome containing the same five concentrations of ZnO-NPs. Results demonstrated that the 1.0 mg/ml ZnO-NPs (crystallite size of 19.73 nm) improved (p < 0.01) the activities of antioxidant enzymes (SOD, CAT, and POD) with concomitantly decreased levels (p < 0.001) of lipid peroxidation (LPO) and reactive oxygen species (ROS) when compared with the other groups. Total spermatozoa motility, rapid velocity, and average path velocity were higher (p < 0.05) with the 1.0 mg/ml ZnO-NPs when compared with the control group. Progressive motility and straight-line velocity were higher (p < 0.05) with the 0.5, 1.0, and 1.5 mg/ml of ZnO-NPs addition compared with the 2.0 mg/ml and control groups. The sperm kinematics parameters; the amplitude of the lateral head displacement, the beat cross frequency, the straightness, and the linearity were not influenced by the ZnO-NPs inclusion. Supra-vital plasma membrane integrity was higher (p < 0.001) with the 0.5 mg/ml and 1.0 mg/ml of ZnO-NPs added groups when compared with either 2.0 mg/ml ZnO-NPs or the control group. The viable sperm with intact acrosome was higher (p < 0.05) in the 1.0 mg/ml ZnO-NPs group compared with the other groups. Low supplementation rates improved (p < 0.05) the DNA integrity when compared with the higher dose (2.0 mg/ml ZnO-NPs). The pregnancy per AI was higher (59.3 %; P < 0.05) in the does inseminated with semen added with the 0.5 mg/ml ZnO-NPs followed by 1.0 mg/ml (58.8 %), 1.5 mg/ml (58.6 %), and 2.0 mg/ml (46.6 %) when compared with the control group (33.3 %). We concluded that the 1.0 mg/ml ZnO-NPs added in the citric acid-fructose yolk extender improved the post-thaw quality of Beetal buck spermatozoa in terms of elevated activities of endogenous antioxidant enzymes, improved structural and functional integrity along with higher fertility.

Investigation of electrical breakdown and heat transfer properties of coconut oil-based nanofluids

This paper presents the evaluation of two grades of coconut oil - RBD (refined, bleached, and deodorized) and virgin coconut oil, plus MIDEL eN1215 as standard natural ester, by dispersing Zinc oxide (ZnO) nanoparticles to improve their breakdown strength and cooling properties. It is shown that a stable nanofluid can be realized at different concentrations of ZnO nanoparticles with or without Oleic acid as a surfactant depending upon the moisture content in oil. Dry and wet nanofluids at 1 and 0.04–0.05 wt% nanoparticles concentration, respectively, showed increased AC breakdown voltage w.r.t individual base oils. As the temperature is raised to 85 °C, the increase in AC breakdown voltage has been insignificant except for wet oils, wherein the AC breakdown voltage increases by 20–36 %. RBD coconut oil shows better viscosity and heat transfer properties, and the latter enhances further by the addition of ZnO nanoparticles. Further, the resistance to thermal aging of various nanofluids at optimum wt% of nanoparticles in terms of various physical (viscosity, pour point, flash point) and electrical properties (resistivity, dissipation factor, AC breakdown voltage) have also been analyzed and discussed.

Influence of the Addition of Zinc Oxide Nanoparticles to Cryopreservation Medium for Dog Epididymal Spermatozoa

The purpose of this study was to assess the effect of different concentrations of zinc oxide nanoparticles (ZnONPs) introduced to an extender for frozen-thawed epididymal dog spermatozoa. Epididymides from 22 castrated dogs were minced and cultured in a Tris buffer. The recovered spermatozoa were diluted in Tris-Citric acid-Fructose (TCF) extender with different concentrations of ZnONPs (100 and 200 µg/mL) and control (0.0 µg/mL). Diluted samples were equilibrated at 5 °C for 2 hours before being packed in 0.25 mL straws and stored in liquid nitrogen (-196 °C). After thawing at 37°C for 30 seconds, sperm motility, viability, membrane integrity, acrosome integrity, DNA integrity, and lipid peroxidation by malondialdehyde (MDA) concentration were all measured. The results were presented as mean ± SEM. Adding 100 and 200 µg/mL ZnONPs to the cryopreservation medium significantly (P < .05) improved motility and membrane integrity compared to the control. Viability and acrosome integrity were considerably (P < .05) better at 100 µg/mL ZnONPs than at 200 µg/mL ZnONPs and the control. MDA concentration was significantly (P < .05) decreased at 100 µg/mL ZnONPs compared to 200 µg/mL ZnONPs and the control. When 100 µg/mL ZnONPs were compared to 200 µg/mL ZnONPs and the control, the percentage of DNA damage was significantly (P < .05) reduced. Consequently, adding 100 µg/mL ZnONPs to TCF extender resulted in a significant increase in the proportion of motility, viability, membrane-intact, and acrosome-intact dog epididymal sperm, as well as the preservation of DNA integrity and the prevention of lipid peroxidation at the membrane level.

Effect of Zinc Oxide Nanoparticles (ZnO-NPs) on Seed Germination Characteristics in Two Brassicaceae Family Species: Camelina sativa and Brassica napus L

Introduction. Zinc is one of the essential micronutrients for living organisms; so, the right performance of several enzymes depends on this element. This micronutrient is a regulator of phytohormones and chlorophyll synthesis, and also, it is an essential element for the carbohydrates’ metabolisms in plants. Considering the relatively high solubility of ZnO-NPs and also the ability of plants to uptake and accumulate these nanoparticles in their biomass, ZnO-NPs can be used as an effective nanofertilizer for plants’ growth. Methods. In the present study, zinc oxide nanoparticles synthesized using chemical method and the effect of ZnO-NPs (as a nanofertilizer) on seeds’ germination, seedlings’ rootlet, seedlings’ plumule, and seedling’s vigour index in two oilseed crops from the Brassicaceae family, including Brassica napus L. and Camelina sativa, were investigated. After treating the seeds with different concentrations of ZnO-NPs (from 0.1 to 1000 ppm) for 6 days, the germination percentage (GP) of each treatment was measured. Results. The results indicated an increase in GP for both plants treated with 10 ppm ZnO-NPs. For B. napus, the maximum GP occurred in treated seeds with 5 ppm ZnO-NPs which showed a 30% increase of GP compared with the control condition. For Camelina, this maximum GP was observed in 0.1 ppm concentration of ZnO-NPs which showed a 15% increase compared with the control condition. After the germination test, germinated seedlings were planted in Hoagland hydroponic solution and treated with ZnO-NPs again for a week. For both species, treatment with ZnO-NPs showed a great effect on rootlet growth, while the effects of these treatments on plumule were negligible. The maximum rootlet length was observed in treated B. napus seedlings with 5 ppm ZnO-NPs which showed a 32% increase in this parameter compared with the control condition. In contrast, the high concentrations of ZnO-NPs showed toxic effects on B. napus seedlings’ rootlets. Results showed a 41% decrease in B. napus seedlings treated with 50 ppm ZnO-NPs compared with control seedlings. Similar results were observed in the treated seedlings of Camelina. For Camelina seedlings treated with 1 ppm ZnO-NPs, 15% increase in rootlets’ length was observed, while treated Camelina seedlings with 50 ppm ZnO-NPs showed a 68% decrease in rootlet length compared with the control condition. The results of this study indicated the potential of using ZnO-NPs as nanofertilizer for B. napus and Camelina in low concentrations (lower than 10 ppm). In addition, these results suggest the toxicity effects of these nanoparticles on both species in concentrations higher than 50 ppm.

Effects of different concentrations of zinc oxide nanoparticles on the quality of ram cauda epididymal spermatozoa during storage at 4°C.

Zinc oxide nanoparticles (ZnO-NPs) are known for their antioxidant effects. In this study, ZnO-NPs were synthesized using aqueous extract of Maclura pomifera fruit; then, their effects on the quality of ram cauda epididymal spermatozoa were evaluated during storage at 4°C. ZnO-NPs formation was characterized by ultraviolet-visible spectroscopy (UV-vis), energy dispersive spectroscopy (EDX), field emission scanning electron microscopes (FE-SEM) and Fourier transform infrared (FTIR) spectroscopy. Cytotoxicity responses were investigated by 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT). Cauda epididymal spermatozoa were obtained from testicles collected from abattoir(s). The sperm samples were pooled. The samples were diluted by extender and supplemented with different concentrations of ZnO-NPs (0, 1, 5 and 25µg/ml) and cooled to 4°C for 72hr. Total motility, viability, DNA and membrane integrity, morphological abnormality, malondialdehyde (MDA) and antioxidant activities: superoxide dismutase (SOD) and total antioxidant capacity (TAC) of cooled diluted samples were evaluated. Addition of 1 μg/ml of ZnO-NPs increased sperm viability under normal conditions (p<.05). Extender supplementation with 1 μg/ml of ZnO-NPs improved sperm total motility, viability, DNA and membrane integrity during storage periods (p<.05). Moreover, using 1 μg/ml of ZnO-NPs improved (p<.05) MDA, TAC and SOD activities after 72 hr compared to other treatments. In conclusion, there were some beneficial effects of ZnO-NPs supplementation in ram epididymal sperm extender during oxidative stress conditions and cooled storage.

Effect of zinc oxide nanoparticles on Triticum aestivum L. and bioaccumulation assessment using ICP-MS and SEM analysis

The impact of zinc oxide nanoparticles (ZnONPs) on Triticum aestivum L. has been explored in this study. The wheat seedlings were allowed to grow on Hoagland and Knop agar medium supplemented with different concentrations of ZnONPs (2500, 5000, 7500, 10,000, and 15,000 ppm) for three weeks. To determine their effect, the growth parameters, viz., wheat seed germination, seedling growth, and chlorophyll content, were taken into consideration. Moreover, the bioaccumulation of ZnONPs in root cellswasdetermined by means of SEM, and zinc content in ZnO NP treatedseedlingswasmeasured byICP-MS. The abatement in seed germination was observed at allconcentrations of ZnONPs used,exceptat 2500 ppm. The plantgrowthand chlorophyllcontent also declined with an increase in ZnONPsconcentration, exceptat 2500 ppm. The maximum reduction in shoot height (23.7%), root length (66.8%), seedling fresh weight (33.8%), and dry weight (54.8%) was noticed at the highest concentration of ZnONPs (15,000 ppm). At 15,000 ppm of ZnONPs, the chlorophyll a, chlorophyll b, andtotalchlorophyll were reduced by 80.6%, 74.2%, and 78.5%, respectively. An elevation in Zn concentration was noticedwith an increase in the concentration as revealed by the ICP-MSanalysis. The TEM micrographs exhibit the accumulation of ZnONPswithin theroot cellsof wheat seedlings treated with ZnONPs (15,000 ppm). Thus, nanoparticles may have a destructive effect on the plant, and therefore their considerate use is advisable.

Synergistic effects of herbal zinc oxide nanoparticles (ZnONPs) and its anti-hyperglycemic and anti-bacterial effects

Zinc deficiency is one of the important nutritional problems, particularly in developing countries. In humans, zinc plays a significant role in the synthesis, secretion and storage of insulin in beta cells. The low level of zinc in the pancreas is associated with increased risks of hyperglycemic conditions. As a novel attempt, herbal-based zinc oxide nanoparticles (ZnONPs) were synthesized from anti-diabetic medicinal plant Costus igneus. The synthesized ZnONPs were characterized by UV–vis Spectroscopy, Fourier Transformer Infra-Red spectroscopy (FTIR), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray analysis (EDX). The zebrafish embryos in the early blastula stage (∼48hpf) were exposed to different concentrations of ZnONPs and its toxic effects were evaluated. Furthermore, the hyperglycemic condition was induced in adult zebrafish using alloxan. The hyperglycemic condition induced zebrafishes were exposed to various concentrations of ZnONPs. Results revealed the promising effects of ZnONPs in lowering the blood glucose level. The ZnONPs also exhibited excellent anti-bacterial activity against Staphylococcus epidermidis and Enterobacter aeurogens. In the present study, ZnONPs exhibited synergistic effects in terms of reducing the blood glucose level in hyperglycemic zebrafish and also showed high anti-bacterial activity.

Biosynthesis of zinc oxide nanoparticles using anjbar (root of Persicaria bistorta) extract and their cytotoxic effects on human breast cancer cell line (MCF-7).

Biosynthesis of nanoparticles (NPs) using biomass is now one of the best methods for synthesising NPs due to their nontoxic and biocompatibility. Plants are the best choice among all biomass to synthesise large-scale NPs. The objectives of this study were to synthesise zinc oxide nanoparticles (ZnO-NPs) using Anjbar (root of Persicaria bistorta) [An/ZnO-NPs] and investigate the cytotoxic and anti-oxidant effects. For this purpose, the An/ZnO-NPs were synthesised by using Bistort extract and characterised using UV-Visible spectroscopy, transmission electron microscope, field emission scanning electron microscope, x-ray diffraction and Fourier-transform infrared spectroscopy. The cytotoxic effects of the An/ZnO-NPs on MCF-7 cells were followed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays at 24, 48, and 72 h. Nuclear morphology changed and apoptosis in cells was investigated using acridine orange/propodium iodide (AO/PI) staining and flow cytometry analysis. The pure biosynthesised ZnO-NPs were spherical in shape and particles sizes ranged from 1 to 50 nm. Treated MCF-7 cells with different concentrations of ZnO-NPs inhibited cell viability in a time- and dose-dependent manner with IC50 about 32 μg/ml after 48 h of incubation. In flow cytometry analysis the sub-G1 population, which indicated apoptotic cells, increased from 12.6% at 0 μg/ml (control) to 92.8% at 60 μg/ml, 48 h after exposure. AO/PI staining showed that the treated cells displayed morphologic evidence of apoptosis, compared to untreated groups.

Synthesis and surface modification of Zinc Nano rods using vermiwash of Eudrilus eugeniae and Functionalization to seed germination of green gram Vigna radiata

The present study reports biosynthesis and characterization of Zinc oxide (ZnO) nanoparticles and its influence on seed germination in the pulse crop, green gram (Vigna radiata). The ZnO nanoparticles (NPs) synthesized through the co-precipitation of Zinc acetate with sodium hydroxide vermiwash obtained from leaf litter compost of Earthworm, Eudrilus eugeniae. The UV- Visible spectrum of ZnO NPs shows an absorption peak at 366 nm with the band gap of 3.54 eV. The XRD study reveals that the synthesized ZnO are of the hexagonal structure with the average crystalline size of 30 nm. The FTIR study confirms the interaction of ZnO with specific functional groups of enzymes presented in the Eudrilus eugeniae compost. SEM study shows the formation of ZnO as agglomeration of nano rods like morphology having the width of 65 nm and the length of 213 nm. The EDAX study confirms the presence of Zinc and Oxygen. The TEM and SAD pattern also reveals that the prepared ZnO NPs are having the rod like morphology and having the width and length of 3 nm and 23 nm respectively. The seed germination of green gram (V.radiata) using different concentrations of ZnO NPs also studied and the detailed results are presented and discussed.

Effect of Zinc Oxide Nanoparticles on Staphylococcus AureusIsolated From CowsʼMastitic Milk

The current spreading of nanomaterial applications supports the search for further possible functions of theses diminutive particles. The antibacterial potentiality of zinc oxide (ZnO) nanoparticles (NPs) againstS. aureus causing mastitis was evaluated using qualitative and quantitative assays. These tests were performed in nutrient broth and nutrient agar following standard methods. In addition, the effect of different concentrations of ZnO nanoparticles on the growth of S. aureus was measured.MIC was determined using six different concentrations of ZnO nanoparticles including 16, 8, 4, 2, 1 and 0.5 mg/ml. The MIC value S. aureus was 0.5 mg/ml. The results showed that ZnO nanoparticles have antibacterial inhibition zone of 29 mm at the concentration of 10 mg/ml against S. aureus., and the antibacterial activity of ZnO nanoparticles increased with increasing powder concentration in vitro.

Synthesis, characterization and conducting properties of novel poly (vinyl cinnamate)/zinc oxide nanocomposites via in situ polymerization

New polymer nanocomposite based on poly (vinyl cinnamate) (PVCin) with zinc oxide (ZnO) was synthesized by in situ polymerization of vinyl cinnamate with different concentrations of ZnO nanoparticles. The composite was characterized through FT-IR, FT-Raman, UV spectroscopy, XRD, HRTEM, FE-SEM, DSC, TGA and electrical conductivity studies. The IR, Raman and UV spectra ascertained the structural variation of PVCin network by the insertion of nanoparticles within the polymer segment. The morphological studies by TEM and FE-SEM photographs indicate that the nanopowder was uniformly dispersed in the polymer. The presence of nanoparticles in the nanocomposite was clearly observed from the XRD studies and the ordered arrangement of nanoparticles within the macromolecular chain of PVCin increased with increase in concentration of nanofillers. DSC results showed that the glass transition temperature and crystalline melting point were increased smoothly with the increase in concentration of nanoparticles. Analysis of TGA studies showed a significant increase in thermal stability with an increase in weight percentage of nanoparticles. The DC conductivity of nanocomposite was increased by ten orders of magnitude with the addition of 7wt% of nano ZnO inclusion. AC conductivity, dielectric constant and dielectric loss tangent of nanocomposite was remarkably increased with increase in ZnO content up to 7wt% of filler particles. Both AC and DC conductivity and dielectric properties were decreased beyond 7wt% loading.

Elucidating the interactions and phytotoxicity of zinc oxide nanoparticles with agriculturally beneficial bacteria and selected crop plants.

There is a growing interest in the use of bioinoculants to assist mineral fertilizers in improving crop production and yield. Azotobacter and Pseudomonas are two agriculturally relevant strains of bacteria which have been established as efficient bioinoculants. An experiment involving addition of graded concentrations of zinc oxide (ZnO) nanoparticles was undertaken using log phase cultures of Azotobacter and Pseudomonas. Growth kinetics revealed a clear trend of gradual decrease with Pseudomonas; however, Azotobacter exhibited a twofold enhancement in growth with increase in the concentration of ZnO concentration. Scanning electron microscopy (SEM), supported by energy-dispersive X-ray (EDX) analyses, illustrated the significant effect of ZnO nanoparticles on Azotobacter by the enhancement in the abundance of globular biofilm-like structures and the intracellular presence of ZnO, with the increase in its concentration. It can be surmised that extracellular mucilage production in Azotobacter may be providing a barrier to the nanoparticles. Further experiments with Azotobacter by inoculation of wheat and tomato seeds with ZnO nanoparticles alone or bacteria grown on ZnO-infused growth medium revealed interesting results. Vigour index of wheat seeds reduced by 40-50% in the presence of different concentrations of ZnO nanoparticles alone, which was alleviated by 15-20%, when ZnO and Azotobacter were present together. However, a drastic 50-60% decrease in vigour indices of tomato seeds was recorded, irrespective of Azotobacter inoculation.

The preparation of γ-crystalline non-electrically poled photoluminescant ZnO–PVDF nanocomposite film for wearable nanogenerators

Polyvinylidene fluoride (PVDF) films are filled with various mass fractions (wt%) of zinc oxide nanoparticles (ZnO-NPs) to fabricate the high performance of a wearable polymer composite nanogenerator (PCNG). The ZnO-NPs can induced a fully γ-crystalline phase in PVDF, where traditional electrical poling is not necessary for the generation of piezoelectric properties. The PCNG delivers up to 28 V of open circuit voltage and 450 nA of short circuit current by simple repeated human finger imparting (under a pressure amplitude of 8.43 kPa) that generates sufficient power to turn on at least 48 commercial blue light emitting diodes (LEDs) instantly. Furthermore, it also successfully charged the capacitors, signifying practical applicability as a piezoelectric based nanogenerator for self-powering devices. The applicability of PCNG by wearable means is clarified when it gives rise to a sensible response, say up to 400 mV of output voltage synchronized with the PCNG embedded human finger in a bending and releasing gesture. UV-visible absorption spectral analysis revealed the possibility of estimating a change in the optical band gap value (Eg), refractive index (n) and optical activation energy (Ea) in different concentrations of ZnO-NP incorporated PVDF nanocomposite films, and it possesses a useful methodology where ZnO-NPs can be used as an optical probe. Near blue light emission is observed from photoluminescence spectra, which are clearly shown from a Commission Internationale de L’Eclairage (CIE) diagram. The piezoelectric charge coefficient of the nanocomposite film is estimated to be −6.4 pC/N, where even electrical poling treatment is not employed. In addition, dielectric properties have been studied to understand the role of molecular kinetic and interfacial polarization occurring in nanocomposite films at different applied frequencies.

Zinc oxide nanoparticles: a 90-day repeated-dose dermal toxicity study in rats.

Zinc oxide (ZnO) works as a long-lasting, broad-spectrum physical sunblock, and can prevent skin cancer, sunburn, and photoaging. Nanosized ZnO particles are used often in sunscreens due to consumer preference over larger sizes, which appear opaque when dermally applied. Although the US Food and Drug Administration approved the use of nanoparticles (NPs) in sunscreens in 1999, there are ongoing safety concerns. The aim of this study was to evaluate the subchronic toxicity of ZnO NPs after dermal application according to the Organization for Economic Cooperation and Development Test Guidelines 411 using Good Laboratory Practice. Sprague Dawley rats were randomly divided into eight (one control, one vehicle control, three experimental, and three recovery) groups. Different concentrations of ZnO NPs were dermally applied to the rats in the experimental groups for 90 days. Clinical observations as well as weight and food consumption were measured and recorded daily. Hematology and biochemistry parameters were determined. Gross pathologic and histopathologic examinations were performed on selected tissues from all animals. Analyses of tissue were undertaken to determine target organ tissue distribution. There was no increased mortality in the experimental group. Although there was dose-dependent irritation at the site of application, there were no abnormal findings related to ZnO NPs in other organs. Increased concentrations of ZnO in the liver, small intestine, large intestine, and feces were thought to result from oral ingestion of ZnO NPs via licking. Penetration of ZnO NPs through the skin seemed to be limited via the dermal route. This study demonstrates that there was no observed adverse effect of ZnO NPs up to 1,000 mg/kg body weight when they are applied dermally.

Zinc Oxide Nanoparticles Induce Rat Retinal Ganglion Cell Damage Through Bcl-2, Caspase-9 and Caspase-12 Pathways

Nanomaterials, including zinc oxide (ZnO) nanoparticles, are being developed for a variety of commercial products. Recent reports showed that cells exposed to ZnO nanoparticles produced severe cytotoxicity accompanied by oxidative stress and genotoxicity. To understand the possible mechanism underlying oxidative stress of ZnO nanoparticles, the present investigation focused on the direct bioactivity of ZnO nanoparticles using a rat retinal ganglion cell (RGC-5) culture. At concentrations relevant to those used in vitro exposure of RGC-5 cells to ZnO nanoparticles, it was found that ZnO nanoparticles could inhibit cell proliferation in time- and concentration-dependent manners. Meanwhile, cell cycle arrest of S and G2/M phases occurred in RGC-5 cells induced by ZnO nanoparticles. Moreover, our results also demonstrated that the overproduction of reactive oxygen species (ROS) and elevated level of caspase-12 as well as decreased levels of bcl-2 and caspase-9 occurred after treatment with different concentrations of ZnO nanoparticles when compared to those in untreated cells. In summary, our findings suggest that ZnO nanoparticles could lead to the over generations of ROS and caspase-12 as well as decreased levels of bcl-2 and caspase-9. These results indicate that bcl-2, caspase-9 and caspase-12 may play significant roles in ZnO nanoparticle-induced RGC-5 cell damage.

Transport of Zn in a sandy loam soil treated with ZnO NPs and uptake by corn plants: Electron microprobe and confocal microscopy studies

The manufacture and multiple uses of zinc oxide (ZnO) nanoparticles (NPs) will represent a possible source of soil contamination. Little is known about how these NPs transport in soil and plants. In this research, the transport of Zn/ZnO NPs in sandy loam soil and the uptake by corn plants (Zea mays) was investigated. Results showed that ZnO NPs exhibit low mobility in a soil column at various ionic strengths. Elution curves suggest that some of the adsorbed ZnO NPs/Zn were released in the presence of chemical perturbations. The breakthrough of released Zn coincided with Fe and Al (indicator of soil colloids) suggesting that soil colloids may act as carriers of strongly adsorbed NPs. By using electron microprobe, Zn/ZnO NPs aggregates were visualized associate with soil clay minerals. The uptake (mg/kg) of Zn by one-month old corn plants varied from 69 to 409 in roots and from 100 to 350 in shoots, respectively, in soils contaminated with different concentrations of ZnO NPs (from 100 to 800mg NPs/kg soil). Confocal microscope images showed that ZnO NPs aggregates penetrated the root epidermis and cortex through the apoplastic pathway; however, the presence of some NP aggregates in xylem vessels suggests that the aggregates passed the endodermis through the symplastic pathway.