Three‑Dimensional Ordered Mesoporous Carbon Spheres Modified with Ultrafine Zinc Oxide Nanoparticles for Enhanced Microwave Absorption Properties

Currently,electromagnetic radiation and interference have a significant effect on the operation of electronic devices and human health systems.Thus,developing excellent microwave absorbers have a huge significance in the material research field.Herein,a kind of ultrafine zinc oxide(ZnO)nanoparticles(NPs)supported on three-dimensional(3D)ordered mesoporous carbon spheres(ZnO/OMCS)is prepared from silica inverse opal by using phenolic resol precursor as carbon source.The prepared lightweight ZnO/OMCS nanocomposites exhibit 3D ordered carbon sphere array and highly dispersed ultrafine ZnO NPs on the mesoporous cell walls of carbon spheres.ZnO/OMCS-30 shows microwave absorbing ability with a strong absorption(−39.3 dB at 10.4 GHz with a small thickness of 2 mm)and a broad effective absorption bandwidth(9.1 GHz).The outstanding microwave absorbing ability benefits to the well-dispersed ultrafine ZnO NPs and the 3D ordered mesoporous carbon spheres structure.This work opened up a unique way for developing lightweight and high-efficient carbon-based microwave absorbing materials.

Zinc oxide nanoparticles reduce the chemoresistance of gastric cancer by inhibiting autophagy

BACKGROUND Gastric cancer(GC)is a common malignancy that results in a high rate of cancerrelated mortality.Cisplatin(DDP)-based chemotherapy is the first-line clinical treatment for GC therapy,but chemotherapy resistance remains a severe clinical challenge.Zinc oxide nanoparticle(ZnO-NP)has been identified as a promising anti-cancer agent,but the function of ZnO-NP in GC development is still unclear.AIM To explore the effect of ZnO-NP on chemotherapy resistance during GC progression.METHODS ZnO-NP was synthesized,and the effect and underlying mechanisms of ZnO-NP on the malignant progression and chemotherapy resistance of GC cells were analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT)assays,colony formation assays,transwell assays,wound healing assays,flow cytometry,and Western blot analysis in GC cells and DDP-resistant GC cells,and by tumorigenicity analyses in nude mice.RESULTS Our data revealed that ZnO-NP was able to inhibit proliferation,migration,and invasion and induce apoptosis of GC cells.Meanwhile,ZnO-NP significantly reduced the half maximal inhibitory concentration(IC50)of DDP for the inhibition of cell proliferation of DDP-resistant SGC7901/DDP cell lines.Autophagy was increased in DDP-resistant GC cells,as demonstrated by elevated light chain 3-like protein 2(LC3II)/LC3I and Beclin-1 expression and repressed p62 expression in SGC7901/DDP cells compared to SGC7901 cells.Mechanically,ZnO-NP inhibited autophagy in GC cells and treatment with DDP induced autophagy,which was reversed by ZnO-NP.Functionally,ZnO-NP attenuated the tumor growth of DDP-resistant GC cells in vivo.CONCLUSION We conclude that ZnO-NP alleviates the chemoresistance of GC cells by inhibiting autophagy.Our findings present novel insights into the mechanism by which ZnO-NP regulates the chemotherapy resistance of GC.ZnO-NP may serve as a potential therapeutic candidate for GC treatment.The potential role of ZnO-NP in the clinical treatment of GC needs clarification in future investigations.

Biosynthesis of Zinc Oxide Nanoparticles Using Ixora Coccinea Leaf Extract—A Green Approach

Green synthesis of metal oxide nanoparticles using plant extract is a promising alternative to traditional method of chemical synthesis. In this paper, we report the synthesis of nanostructured zinc oxide particles by biological method. Highly stable and spherical zinc oxide nanoparticles are produced by using zinc acetate and Ixora coccinea leaf extract. Formation of zinc oxide nanoparticles has been confirmed by UV-Vis absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Dynamic light scattering analysis (DLS), zetapotential study and Scanning Electron Microscope with the Energy Dispersive X-ray studies (EDX). Dynamic light scattering analysis shows average particle size of 145.1 nm whereas high zeta potential value confirms the stability of formed zinc oxide nanoparticles. The Scanning Electron Microscope reveals spherical morphology of nanoparticles and Energy Dispersive X-ray analysis confirms the formation of highly pure zinc oxide nanoparticles. The zinc oxide nanoparticles from Ixora coccinea leaves are expected to have applications in biomedical, cosmetic industries, biotechnology, sensors, medical, catalysis, optical device, coatings, drug delivery and water remediation, and also may be applied for electronic and magneto-electric devices. This new eco-friendly approach of synthesis is a novel, cheap, and convenient technique suitable for large scale commercial production.

Effect of Zinc Oxide Nanoparticles on Denitrification and Denitrifying Bacteria Communities in Typical Estuarine Sediments

For revealing the effects of increasing of zinc oxide nanoparticles(ZnO NPs)on denitrification and denitrifying bacteria communities in estuarine sediments,the surface sediments of two typical estuaries(the Yangtze River Estuary and the Yellow River Estuary)were added with medium concentration(170mgL−1)and high concentration(1700mgL−1)of ZnO NPs for anaerobic cul-ture in laboratory.The concentration of NO_(3)^(−)and NO_(2)^(−),the reductase activity and denitrification rate were measured by physico-chemical analysis,nirS gene abundance and denitrifying bacteria communities by molecular biological methods.The results showed that ZnO NPs inhibited NO_(3)^(−), NO_(2)^(−)reduction process and NO_(3)^(−), NO_(2)^(−)reductase activity,and a stronger inhibition effect resulting from the higher ZnO NPs concentration.ZnO NPs decreased nirS gene abundance and community diversity of denitrifying bacteria.In addition,the inhibition degree of ZnO NPs on the denitrification process of sediments in different estuaries was different.These results were of great significance for evaluating the potential ecological toxicity and risks of nanomaterials in estuaries.

Unravel the potential of zinc oxide nanoparticle-carbonized sawdust matrix for removal of lead(Ⅱ) ions from aqueous solution

Zinc oxide nanoparticles(ZnOnp) are molecular nanoparticles synthesized by a chemical precipitation method from zinc nitrate tetrahydrate and sodium hydroxide.Carbonized sawdust(CSD) was prepared from sawdust obtained from a local wood mill.The matrix of both provides a better material as an adsorbent.The present study applied the functionality of ZnOnp,CSD,and ZnOnp-CSD matrix as adsorbent materials for the removal of Pb(Ⅱ) ions from aqueous solution.The method of batch process was employed to investigate the potential of the adsorbents.The influence of pH,contact time,initial concentration of adsorbate,the dosage of adsorbents,and the temperature of adsorbate-adsorbent mixture on the adsorption capacity were revealed.The adsorption isotherm studies indicate that both Freundlich and Langmuir isotherms were suitable to express the experimental data obtained with theoretical maximum adsorption capacities(q_(m)) of 70.42,87.72,and 92.59 mg·g^(-1) for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix,respectively.The separation factors(R_(L)) calculated showed that the use of the adsorbents for the removal of Pb(Ⅱ) ions is a feasible process with R_(L) <1.The thermodynamic parameters obtained revealed that the processes are endothermic,feasible,and spontaneous in nature at 25-50℃.Evaluation of the kinetic model elected that the processes agreed better with pseudo-second order where the values of rate constant(k_2) obtained for the adsorption of Pb(Ⅱ) ions onto ZnOnp,CSD,and ZnOnp-CSD matrix are 0.00149,0.00188,and 0.00315 g·mg^(-1)·min^(-1),respectively.The reusability potential examined for four cycles indicated that the adsorbents have better potential and economic value of reuse and the ZnOnp-CSD matrix indicates improved adsorbent material to remove Pb(Ⅱ) ions from aqueous solution.

Ameliorative effects of melatonin and zinc oxide nanoparticles treatment against adverse effects of busulfan induced infertility in male albino mice

Testicular damage is one of the most hazardous effects as it’s associated with azoospermia.Busulfan(Bu)is a highly toxic chemotherapeutic drug that affects testis.Thirty male Swiss albino mice divided into six groups of 5 animals each.Control(oral 0.9%saline daily for 75 days);Mel(20 mg/kg/day orally for 30 days);ZnO NPs(5 mg/kg/day i.p.for 30 days);BU(single i.p.injection of 40 mg/kg and then left for 45 days);BU+Mel(single 40 mg/kg dose of BU and left for 45 days followed by 20 mg/kg/day Mel for 30 days);BU+ZnO NPs(single dose of 40 mg/kg of BU and left for 45 days,then 5 mg/kg/day ZnO NPs for 30 days).Preparation and Characterization of ZnO NPs.Specimens from testis prepared for ultrastructural investigations using TEM after Masson’s trichrome and toluidine blue staining.BU induced histological and ultrastructural damage of the testis.Moreover,the present results could be concluded that Mel or ZnO NPs can protect the testicular tissue against ultrastructural alterations induced by BU by its antioxidant and anti-apoptotic effects.

Zinc oxide nanoparticles and epibrassinolide enhanced growth of tomato via modulating antioxidant activity and photosynthetic performance

Nanotechnology has greatly expanded the applications of nanoparticles(NPs)domain in the scientific field.In this context,the zinc oxide nanoparticles(ZnO-NPs)and 24-epibrassinolide(EBL)has been revealed to positively regulate plant metabolism and growth.In the present study,we investigated the role of ZnO-NPs and EBL in the regulation of plant growth,photosynthetic efficiency,enzymes activities and fruit yield in tomato.Foliar treatment of ZnO-NPs at three levels(10,50 or 100 ppm)and EBL(10^(−8) M)were applied separately or in combination to the foliage of plant at 35-39 days after sowing(DAS);and the control plants were treated with double distilled water(DDW)only at the same time interval.Among different tested concentrations of ZnO-NPs and/or EBL,the combined spray of 50 ppm of ZnO-NPs and 10^(−8) M of EBL proved to be best,and considerably increased the growth,photosynthetic efficiency,biochemical enzymes activities as well as fruit yield.Besides,the performance of the antioxidant enzymes viz catalase,peroxidase and superoxide dismutase were also increased after the combined application of ZnO-NPs and EBL in Lycopersicon esculentum.Therefore,it is suggested that combined application of 50 ppm of ZnO-NPs and 10−8 M of EBL is the best combination can be applied to increase the performance and yield of L.esculentum.

Synthesis of Zinc Oxide Nanoparticles with Good Photocatalytic Activities under Stabilization of Bovine Serum Albumin

Zinc oxide nanoparticles were synthesized using bovine serum albumin as stabilizers through a facile one-pot strategy in aqueous media. The morphology and crystal phase of the zinc oxide nanoparticles were determined by transmission electron microscopy, X-ray diffractograms, and Fourier transform infrared spectroscopy. The synthesized ZnO nanoparticles exhibited strong absorption and photoluminescence properties in the visible wavelength region based on the fluorescence and UV-visible spectroscopy. Based on the results, the zinc oxide nanoparticles could effectively degrade the organic dyes through the mediation of the hydroxyl radical under visible light irradiation. Furthermore, the zinc oxide nanoparticles show good recycling stability during the photocatalytic experiments. These results suggested that the as-prepared zinc oxide nanoparticles might be used as a potential photocatalyst to efficiently treat the organic pollutants.

Zinc oxide nanoparticles inhibit osteosarcoma metastasis by downregulatingβ-catenin via HIF-1α/BNIP3/LC3B-mediated mitophagy pathway

Osteosarcoma(OS)therapy faces many challenges,especially the poor survival rate once metastasis occurs.Therefore,it is crucial to explore new OS treatment strategies that can efficiently inhibit OS metastasis.Bioactive nanoparticles such as zinc oxide nanoparticles(ZnO NPs)can efficiently inhibit OS growth,however,the effect and mechanisms of them on tumor metastasis are still not clear.In this study,we firstly prepared well-dispersed ZnO NPs and proved that ZnO NPs can inhibit OS metastasis-related malignant behaviors including migration,invasion,and epithelial-mesenchymal transition(EMT).RNA-Seqs found that differentially expressed genes(DEGs)in ZnO NP-treated OS cells were enriched in wingless/integrated(Wnt)and hypoxia-inducible factor-1(HIF-1)signaling pathway.We further proved that Zn^(2+)released from ZnO NPs induced downregulation ofβ-catenin expression via HIF-1α/BNIP3/LC3B-mediated mitophagy pathway.ZnO NPs combined with ICG-001,aβ-catenin inhibitor,showed a synergistic inhibitory effect on OS lung metastasis and a longer survival time.In addition,tissue microarray(TMA)of OS patients also detected much higherβ-catenin expression which indicated the role ofβ-catenin in OS development.In summary,our current study not only proved that ZnO NPs can inhibit OS metastasis by degradingβ-catenin in HIF-1α/BNIP3/LC3B-mediated mitophagy pathway,but also provided a far-reaching potential of ZnO NPs in clinical OS treatment with metastasis.

A synergistic effect of zinc oxide nanoparticles and polyethylene butene improving the rheology of waxy crude oil

This research examined the use of 75 nm zinc oxide nanoparticles(nano ZnO)and polyethylene butene(PEB)to decrease the viscosity of Nigerian waxy crude oil.The rheology of the crude oil was assessed by measuring the viscosity and shear stress of samples containing PEB at 500,1000,2000,3000,4000 or 5000 ppm and nano ZnO at 1,2,3 or 4 wt% between 10 and 35℃ at shear rates from 1.7 to 1020 s^(-1).Rheological modeling indicated that a power law pseudoplastic model was the best fit for the experimental data,giving a regression coefficient of 0.99.The addition of these inhibitors induced Newtonian fluid behavior in the crude samples such that the shear stress-shear rate relationship plots were linear at all temperatures.The optimum concentrations of the inhibitors in this study were 2000 ppm PEB(providing a 33% viscosity reduction)and 1 wt% nano ZnO(providing a 26% viscosity reduction).A combination of these additives at these concentrations provided a synergistic effect and gave a greater viscosity reduction of 41%.This work demonstrates that a blend of ZnO nanoparticles and PEB can improve the flowability of waxy crude.

Synthesis and Characterization of Zinc Oxide and Zinc Oxide Doped with Chlorine Nanoparticles as Novel <i>α</i>-Amylase Inhibitors

In this study we used a chemical solution method from oxalic acid (OX. acid) and zinc acetate (ZnAc) to prepare Zinc Oxide nanoparticles (ZnONPs) and Zinc Oxide nanoparticles doped with Chlorine (Cl:ZnONPs). The characterizations (FTIR, X-ray, SEM, TEM) of ZnONPs and Cl:ZnONPs were determined. Amylase inhibitors of ZnONPs and Cl:ZnONPs also were determined. SEM indicated that the ZnONPs and Cl:ZnONPs have an average particle size of 46.65 - 74.64 nm. TEM images of the ZnONPs and Cl:ZnONPs showed the round shaped. Compounds b, d and e exhibited significant inhibitory activity against amylase enzyme (from 69.21 ± 1.44 to 76.32 ± 0.78), respectively, and were comparable with that of acarbose (86.32 ± 0.63) at 1000 μg, thereby, projecting ZnONPs and Cl:ZnONPs as α-amylase inhibitors.

Ecotoxicological effect of zinc oxide nanoparticles on soil microorganisms

The widespread production and use of zinc oxide nanoparticles （ZnO-NPs） in recent years have posed potential threat to the ecosystem. This study aimed to investigate the ecotoxicological effect of ZnO-NPs on soil microorganisms using laboratory microcosm test. Respira- tion, ammonification, dehydrogenase （DH） activity, and fluorescent diacetate hydrolase （FDAH） activity were used as ecotoxicological parameters. The results showed that in the neutral soil treated with 1 mg ZnO-NPs per g soil （fresh, neutral）, ammonification was significantly inhibited during the study period of three months, but the inhibition rate decreased over increasing time. Inhibition in respira- tion was observed in the first month of the test. In various ZnO-NPs treatments （1 rag, 5 rag, and 10 mg ZnO-NPs per g soil）, DH activity and FDAH activity were inhibited during the study period of one month. For both enzyme activities, there were positive dose-response relationships between the concentration of ZnO-NPs and the inhibition rates, but the curves changed over time due to changes of ZnO-NPs toxicity. Soil type affected the toxicity of ZnO- NPs in soil. The toxicity was highest in the acid soil, followed by the neutral soil. The toxicity was relatively low in the alkaline soil. The toxicity was not accounted for by the Zn2＋ released from the ZnO-NPs. Direct interaction of ZnO-NPs with biologic targets might be one of the reasons. The adverse effect of ZnO-NPs on soil micro- organisms in neutral and acid soils is worthy of attention.

Preparation and characterization of zinc oxide nanoparticles

In the present study, the zinc oxide nanoparticles(ZnO NPs) were prepared by using a sol-gel method. The characterization of ZnO NPs, such as particle size, morphology, crystal form, optical properties and p H-responsive behavior, was carried out. The in vitro anti-tumor activity of ZnO NPs was evaluated on PC-3M and 4T1 cell lines. The results indicated that ZnO NPs were spherical NPs with uniform particle size, excellent fluorescence properties, and p H-responsive behavior. The in vitro anti-tumor activity of ZnO NPs was observed on PC-3M and 4T1 cell lines. Considering to above characteristics, Zn O NPs could be used as drug delivery carries for loading active compound performing therapeutic and diagnostic effect.

Detoxication and Theranostic Aspects of Biosynthesised Zinc Oxide Nanoparticles for Drug Delivery

Bioactive materials obtained from plant bio-resources offer immense attention for development and production of nanotechnology enabled products for biomedical applications.In the present study,Ficus hispida leaf extract(FHLE)was used as a stabilising agent for the environmentally benign synthesis of zinc oxide nanoparticles(ZnO-NPs)which were investigated for prospective versatile applications(anticancer and photocatalytic activities).The formation of ZnO-NPs was confirmed by UV–visible spectra.Wurtzite(hexagonal)form of the herb-assisted synthesised ZnO-NPs with particle size ranging from 20 to 200 nm was confirmed by transmission electron microscopy(TEM)analysis.In vitro analysis was carried out against Dalton's lymphoma ascites(DLA)cell lines by trypan blue assay,the results revealed 96%inhibition at concentration of 200μg ml-1,and the photodegradation experiments carried out for degradation of Congo red revealed complete degradation of the dye after 70 min of exposure to UV light.

Evaluation of antibacterial activity of zinc oxide nanoparticles synthesized using phycobilins of Anabaena variabilis NTSS17

Objective:To evaluate the antibacterial activity of zinc oxide nanoparticles synthesized using phycobilins of Anabaena variabilis NTSS17.Methods:The cyanobacterial isolate was collected from paddy field and morphologically identified as Anabaena variabilis NTSS17,that produces a pigment i.e.phycobiliproteins.The biosynthesized zinc nanoparticles were characterized by different spectroscopic and analytical techniques such as UV-visible spectrophotometer,Fourier transform infrared spectroscopy and X-ray diffraction which confirmed the formation of zinc nanoparticles.Results:Antibacterial activity of zinc oxide nanoparticles was examined against Escherichia coli,Rhodococcus rhodochrous and Pseudomonas aeruginosa.The maximum zone of inhibition occurred at 5 mg/1000 mL concentration of zinc oxide nanoparticles.Conclusions:Due to potent antimicrobial and intrinsic properties of zinc oxide,it can be actively used for biomedical applications.

Phenotype,Physiology,and Gene Expression of Barley Seedlings in Response to Nano Zinc Oxide Stress

In recent years,zinc oxide nanoparticles(ZnO NPs)have been widely used as zinc fertilizers and pesticides.The use of ZnO NPs in this way can provide benefits to humans,but also has potential risks.ZnO NPs inevitably enter the environment during their production and use,which affects the ecological environment and crop growth.In order to investigate the phenotype,physiology,and gene expression of barley(Hordeum vulgare L.)seedlings under ZnO NPs stress,the barely cultivars ZJU3(P21),Golden Promise(GP)and L23 were chosen for study.Different ZnO NPs concentrations were applied to compare the physiological and biochemical indexes of the barley seedlings and the responses of six stress-related genes,when seedlings were cultured to the two-leaf stage through hydroponics.The results showed that the density of brown spots on the leaf surface increased with increasing ZnO NPs concentration.ZnO NPs stress inhibited the root growth of barley seedlings,and P21 was the most sensitive.Furthermore,ZnO NPs stress could stimulate plants to produce a large number of reactive oxygen species(ROS),resulting in an imbalance between the production and removal of ROS and membrane lipid peroxidation in plants.This imbalance inhibited the growth and development of the barley seedlings.With increasing ZnO NPs concentration,the activity of superoxide dismutase was gradually increased,the activity of catalase was progressively decreased,and the contents of malondialdehyde and proline were increased.Compared with the control,among six stress-related genes,the expression levels of five genes were downregulated and one gene was upregulated in the experimental group.This study preliminarily revealed the toxic effect of ZnO NPs on seedlings and the effect on the expression of stress-related resistance genes in different barley varieties.

Significant Lifetime Enhancement in QLEDs by Reducing Interfacial Charge Accumulation via Fluorine Incorporation in the ZnO Electron Transport Layer

ZnO nanoparticles are widely used for the electron transport layers(ETLs)of quantum dots light emitting devices(QLEDs).In this work we show that incorporating fluorine(F)into the ZnO ETL results in significant enhancement in device electroluminescence stability,leading to LT50 at 100 cd m^(−2) of 2,370,000 h in red QLED,47X longer than the control devices.X-ray photo-electron spectroscopy,time-of-flight secondary ion mass spectroscopy,photoluminescence and electrical measurements show that the F passivates oxygen vacancies and reduces electron traps in ZnO.Transient photoluminescence versus bias measurements and capacitance-voltage-luminance measurements reveal that the CF4 plasma-treated ETLs lead to increased electron concentration in the QD and the QD/hole transport layer interface,subsequently decreasing hole accumulation,and hence the higher stability.The findings provide new insights into the critical roles that optimizing charge distribution across the layers play in influencing stability and present a novel and simple approach for extending QLED lifetimes.

Adsorption of Chromium (VI) Using Nano-ZnO Doped Scrap Tire-Derived Activated Carbon

Nowadays, nano mineral modified biochars show a promising adsorption capacity for pollutants removals by combining the advantages of porous structure of biochar and unique property of nano minerals. In this work, nano-zinc oxide doped scrap tire derived activated carbon (nZnO-STAC) was synthesized by wetness impregnation method. Equilibrium data were analyzed using Langmuir and Freundlich isotherm models while the kinetics of the process were examined using Lagergren Pseudo-first and second order, intraparticle diffusion and Elovich kinetic models. Characterization of the activated carbon by Powder X-ray Diffraction (PXRD). The surface groups present on the activated carbon surface were determined using the Fourier Transform Infra-Red Spectroscopy (FTIR) analysis. Optimization studies were carried out to determine the effects of pH, initial metal concentration, adsorbent dosage, contact time and adsorbent particle size on the Cr (VI) removal efficiency. The results showed optimum Cr (VI) removal at pH 3, 10 mg/L concentration, 120 minutes of contact using 1000 - 1400 μm adsorbent particle size at a dosage of 2.5 g/L. The adsorbent structure was found to be predominantly amorphous. The chromium removal efficiency of the adsorbent was around 81.6%. Of the tested kinetic models, the pseudo-second order model exhibited the best fit with the experimental data with an R2 value of 0.9744. This study clearly demonstrates the feasibility of using the nano-ZnO doped scrap tyre derived activated carbon adsorbent for the remediation of chromium (VI) polluted industrial wastewaters.

Effect of pH on Crystal Size and Photoluminescence Property of ZnO Nanoparticles Prepared by Chemical Precipitation Method

The effects of pH value on crystal size and optical property of zinc oxide nanoparticles prepared by chemical precipitation method were investigated.Prepared samples have been characterized by means of X-ray diffraction,scanning electron microscopy,ultraviolet-visible spectrometer and photoluminescence spectrometer.From X-ray diffraction profile,it is found that the particle size of sample increases from 13.8 to 33 nm when the pH value of the solution was increased from 6 to 13.Microstructural study also shows that the particle size increases with pH value.Hexagonal shape of the zinc oxide nanoparticle has been confirmed by the scanning electron microscopy image.The recorded ultraviolet-visible spectrum shows excitonic absorption peaks around 381 nm.The energy gap of the prepared samples has been determined from the ultraviolet-visible absorption spectrum,effective mass model equation and Tauc＇s relation.It was found that the energy gap of the prepared samples decreases with increase in pH value.The recorded blue shift confirmed the quantum confinement effect in the prepared zinc oxide samples.Photoluminescence spectrum infers that the increase in pH value shifts the ultraviolet-visible emission but not the violet and green emissions.

Comparative cytotoxicity of nanoparticles and ions to Escherichia coli in binary mixtures

The objective of this study was to understand toxicity of mixture of nanoparticles （NPs） （ZnO and TiO2） and their ions to Escherichia coll. Results indicated the decrease in percentage growth of E. coli with the increase in concentration of NPs both in single and mixture setups. Even a small concentration of I mg/L was observed to be significantly toxic to E. coli in binary mixture setup （exposure concentration： 1 mg/L ZnO and 1 mg/L TiO2; 21.15% decrease in plate count concentration with respect to control）. Exposure ofE. coli to mixture of NPs at 1000 mg/L （i.e., 1000 mg/L ZnO and 1000 mg/L TiO2） resulted in 99.63% decrease in plate count concentration with respect to control. Toxic effects of ions to E. coli were found to be lesser than their corresponding NPs. The percentage growth reduction was found to be 36% for binary mixture of zinc and titanium ions at the highest concentration （i.e., 803.0 mg/L Zn and 593.3 mg/L Ti where ion concentrations are equal to the Zn ions present in 1000 mg/L ZnO NP solution and Ti＋4 ions present in 1000 mg/L TiO2 NP solution）. Nature of mixture toxicity of the two NPs to E. coli was found to be antagonistic. The alkaline phosphatase （Alp） assay indicated that the maximum damage was observed when E. coli was exposed to 1000 mg/L of mixture of NPs. This study tries to fill the knowledge gap on information of toxicity of mixture of NPs to bacteria which has not been reported earlier.