ZnO Nanocrystals Research Articles

ZnO/silica quasi core/shell nanoparticles as electron transport materials for high-performance quantum-dot light-emitting diodes

Quantum dot light-emitting diodes (QLEDs) are considered as the ideal candidate for next-generation displays, solid-state lighting, and optical communication applications. Although the efficiency of QLEDs has been significantly improved to the level comparable to that of organic light-emitting diodes in recent years, simultaneously achieving high efficiency and high brightness still remains challenging for QLEDs. In this work, we report a facile and effective electron-transport-layer interface control strategy of incorporating 3-aminopropyl triethoxysilane (APTES) into a ZnO nanocrystal-solution to enhance charge injection balance and suppress interfacial exciton quenching via in-situ formation of ZnO/organic silica (hereinafter referred to as ZnO/SiO2) quasi core/shell nanoparticles in the solution, enabling red QLEDs to exhibit a maximum luminance intensity of 261,700 cd m−2, a peak external quantum efficiency (EQE) of 19.0%, and low efficiency roll-off at high luminance (an EQE up to 16.8% remained at a brightness of 200, 000 cd m−2). Our results demonstrate that substituting quasi core/shell-structured ZnO/SiO2 nanoparticles for traditional ZnO nanocrystals as electron transport materials is a simple and effective means of fabricating QLEDs with both high efficiency and high luminance, which is expected to facilitate the development of QLED technology toward practical applications in lighting, displays and optical communication.

Enhanced performance of ZIF-8 nanocrystals hybrid monolithic composites via an in-situ growth strategy for efficient capillary microextraction of perfluoroalkyl phosphonic acids

Enrichment of perfluoroalkyl phosphonic acids (PFPAs) is of great significance and challenging for environmental monitoring, due to their toxic and persistent nature, highly fluorinated character as well as low concentration. Herein, novel metal-organic frameworks (MOFs) hybrid monolithic composites were prepared via metal oxide-mediated in situ growth strategy and utilized for capillary microextraction (CME) of PFPAs. A porous pristine monolith was initially obtained by copolymerization of the zinc oxide nanoparticles (ZnO-NPs)-dispersed methacrylic acid (MAA) with ethylenedimethacrylate (EDMA) and dodecafluoroheptyl acrylate (DFA). Afterwards, nanoscale-facilitated transformation of ZnO nanocrystals into the zeolitic imidazolate framework-8 (ZIF-8) nanocrystals was successfully realized via the dissolution-precipitation of the embedded ZnO-NPs in the precursor monolith in the presence of 2-methylimidazole. Experimental and spectroscopic results (SEM, N2 adsorption-desorption, FT-IR, XPS) revealed that the coating of ZIF-8 nanocrystals significantly increased the surface area of the obtained ZIF-8 hybrid monolith and endowed the material abundant surface-localized unsaturated zinc sites. The proposed adsorbent showed highly enhanced extraction performance for PFPAs in CME, which was mainly ascribed to the strong fluorine affinity, Lewis acid/base complexing, anion-exchange, and weakly π-CF interaction. The coupling of CME with LC-MS enables effective and sensitive analysis of ultra-trace PFPAs in environment water and human serum. The coupling method demonstrated low detection limits (2.16–4.12 ng L−1) with satisfactory recoveries (82.0–108.0%) and precision (RSDs ≤6.2%). This work offered a versatile route to design and fabricate selective materials for emerging contaminant enrichment in complicated matrices.

Temperature Dependence on Structural Properties of Liquid Phase Synthesized ZnO

Transparent conducting oxide material, ZnO nanoparticles has been synthesized using inexpensive and eco-friendly synthesis procedures with less or environmental pollutants and no liquid waste products. The effect of the temperatures on the structural properties for the synthesized ZnO nanocrystals has been investigated. In this study, we report an easy, low-cost, re-producible method for synthesizing ZnO nanoparticles by means of the liquid phase method. The ZnO nanocrystals were synthesized using the wet chemical route and the effect of temperature variation on the structural properties of investigated synthesized using powder x-ray diffractogram (XRD). The temperatures for the synthesis were varied from 120 °C to 200 °C in steps of 20 °C. The results show that, during the first stage of the synthesis of ZnO (at 120 °C), the XRD diffraction pattern confirms the cubic structure of zinc peroxide and the XRD pattern of the samples obtained at temperatures of 140 °C, 160 °C, 180 °C and 200 °C were confirmed to be hexagonal (wurtzite) crystal structure of ZnO. The XRD diffraction patterns of the 140 °C and 160 °C samples show some impurity phases which were associated with the zinc acetate by-product which is a colloid complex of water and methyl succinate and were removed by evaporation as temperatures were increased to 180 °C and 200 °C respectively. As temperature increases, the peak of the diffractograms of the sample becomes sharper and narrow indicating a decrease in width. A shift in peak positions to higher angles was observed and the positional parameter, bond angle, β, average crystallite size, APF, number of unit cells and density generally increase with temperature. However, the lattice parameters ‘a’ and ‘c’, bond lengths b and b1, bond angle, α, dislocation density, strain and unit cell volume were found to generally decrease with temperature.

UV Suppression in photoluminescence emission and improved photocatalytic activity under sunlight in nanoassemblies and nanocrystals of ZnO

The objective of present study is to analyse the impact of alterations in the shape and size of ZnO on PL emission and photocatalytic activity of ZnO nanostructures. The study also aims at addressing the knowledge gap between synthesis approach and its role in governing the optical, morphological and photocatalytic behaviour. Here, we report the facile and controlled synthesis of nanoassemblies (NA) and nanocrystals (NC) of ZnO via soft chemical approach. The synthesized ZnO nanostructures were characterized using TEM, SEM, UV–vis and photoluminescence (PL) measurement. The morphology of ZnO is tuned by adjusting the molar ratio of DEG and water whose impact is also noticed on the PL emission spectra. PL analysis revealed that the UV emission (378 nm) and defect levels attributed to Zn interstitial (Zni) and oxygen interstitial (Oi) are stabilized at ambient condition. However, UV band gap emission peak is significantly reduced making it lesser distinct by introducing appropriate amount of water in diethylene glycol (DEG) solvent during ZnO synthesis. Such controlled nanostructured growth demonstrates potential for sustainable photocatalytic activity under both UV and Sunlight irradiation. The study shows 100% photodegradation efficiency for ZnO NA and it get completely irradiated methylene blue dye within 90 min under UV light, whereas only 70% dye is degraded in 100 min for ZnO NC. Under natural Sunlight, ZnO NA has been achieved 97% degradation efficacy in 75 min; however, ZnO NC has degraded only 89% of dye. Further, the degradation of dye over ZnO was observed to follow pseudo first order reaction kinetic model that is used to determine the rate constant of the reaction.

Toward Imaging Defect-Mediated Energy Transfer between Single Nanocrystal Donors and Single Molecule Acceptors.

Defect-mediated energy transfer is an energy transfer process between midgap electronic states in a semiconductor nanocrystal (NC) and molecular acceptors, such as fluorescent dye molecules. Super-resolution fluorescence microscopy represents an exciting technique for pinpointing the nanoscale positions of lattice defect sites in, for example, a micrometer-sized particle or thin film sample by spatially resolving the location of the acceptor dye molecules with nanometer resolution. Toward this goal, our group performed ensemble-level, time-resolved fluorescence spectroscopy measurements of ZnO NC/Alexafluor 555 (A555) mixtures and calculated that the emissive defect sites are located, on average, 0.5 nm from the NC surface [Nilsson Z. N.; J. Chem. Phys.2021, 154 ( (5), ), 054704]. However, ensemble-level measurements cannot spatially resolve the defect sites on single particles, nor can they distinguish between surface-adsorbed dye molecules that participate in the energy transfer (EnT) process from those that do not. In this work, we compared the photoluminescence intensity trajectories of 789 isolated, single ZnO NC donors to those of 73 non-specifically bound and five specifically bound ZnO NC/A555 pairs, where the donor and acceptor centroid positions were separated by a distance that was smaller than our localization precision (40 nm). We observed minor fluorescence intensity fluctuations in the donor and defect channels instead of clear anticorrelated intensity fluctuations, which could be explained by (1) the presence of multiple emissive defect sites per NC, (2) donor-acceptor separation distances slightly larger than the Förster radius (R 0 = 3.1 nm; defined as the distance at which EnT is 50% efficient), and/or (3) poor dipole-dipole coupling. The single molecule imaging methodology we developed, an alternating ultraviolet-visible excitation sequence combined with multicolor photon detection, successfully distinguishes specifically bound and non-specifically bound NC/dye pairs and can be applied to study a wide range of hybrid NC/dye energy transfer systems.

Ceramic ZnO-SnO2-Fe2O3 Powders and Coatings -Effective Photogenerators of Reactive Oxygen Species

Ceramic ZnO-SnO2-Fe2O3 powders and transparent coatings on glasses prepared using the non-isothermal polymer-salt method demonstrate a strong ability to generate chemically active oxygen species under UV and visible irradiation. Crystal structures and morphologies of these materials were studied using the XRD and the SEM analysis. It was found that there are significant differences in the crystal structure of ceramic powders and thin coatings. The powders consist of randomly oriented oxide nanocrystals of size ~47 nm. The strong orientation of the ZnO nanocrystals due to their interaction with the glass substrate is observed in the coating structure. Experimental data show that thin ceramic coatings are transparent (~90%) in the visible spectral range and the band gap of the ceramic material is 3.44 eV. The band gap value of this multi-component ceramic material is described sufficiently using Verlag’s law. Ceramic powders and coatings demonstrate the intensive photogeneration of reactive oxygen species, both in liquid and air. High photocatalytic activity of ZnO-SnO2-Fe2O3 ceramic coatings and powders was observed upon the oxidation of the diazo dye, Chicago Sky Blue. In the presence of transparent photocatalytic coating, the value of the constant rate of the dye photodecomposition was high (k = 0.056 min−1). It was found that, in spite of their short life time, photogenerated reactive oxygen species demonstrate the ability to decompose dye molecules located up to a distance of 0.5 mm from the surface of ceramic coating. Obtained experimental results suggest that the prepared ceramic materials are promising for different practical applications of the photocatalytic materials.

Ho and Nd ion beam modifications of ZnO thin films

This work reports the influence of the annealing temperature on the structural and optical characteristics of ZnO films implanted with Ho+ and Nd+ ions. ZnO films have been synthesized in the form of arrays of highly oriented nanorods on silicon substrates by RF magnetron sputtering. Ion implantations led to an increase in the crystallinity level of the films. The temperature changes in the lattice parameters and sizes of ZnO nanocrystals in nanorods are presented. Threshold temperatures of bulk crystallization and the photoluminescent properties of nanorods were established. It is shown that the implanted elements are almost uniformly distributed throughout the thickness of the films and accumulate at the SiOx/Si interface during high-temperature annealing.

Multiphoton excited singlet/triplet mixed self-trapped exciton emission

Multiphoton excited luminescence is of paramount importance in the field of optical detection and biological photonics. Self-trapped exciton (STE) emission with self-absorption-free advantages provide a choice for multiphoton excited luminescence. Herein, multiphoton excited singlet/triplet mixed STE emission with a large full width at half-maximum (617 meV) and Stokes shift (1.29 eV) has been demonstrated in single-crystalline ZnO nanocrystals. Temperature dependent steady state, transient state and time-resolved electron spin resonance spectra demonstrate a mixture of singlet (63%) and triplet (37%) mixed STE emission, which contributes to a high photoluminescence quantum yield (60.5%). First-principles calculations suggest 48.34 meV energy per exciton stored by phonons in the distorted lattice of excited states, and 58 meV singlet-triplet splitting energy for the nanocrystals being consistent with the experimental measurements. The model clarifies long and controversial debates on ZnO emission in visible region, and the multiphoton excited singlet/triplet mixed STE emission is also observed.

Promotional Effect and Molecular Mechanism of Synthesized Zinc Oxide Nanocrystal on Zirconia Abutment Surface for Soft Tissue Sealing

Studies have confirmed that tooth loss is closely related to systemic diseases, such as obesity, diabetes, cardiovascular diseases, some types of tumors, and Alzheimer’s disease. Among many methods for tooth restoration, implant restoration is the most commonly used method. After implantation, long-term stability of implants requires not only good bone bonding but also good soft tissue sealing between implants and surrounding soft tissues. The zirconia abutment is used in clinical implant restoration treatment, but due to the strong biological inertia of zirconia, it is difficult to form stable chemical or biological bonds with surrounding tissues. In this study, we investigated synthesized zinc oxide (ZnO) nanocrystal on the zirconia abutment surface by the hydrothermal method to make it more beneficial for soft tissue early sealing and the molecular mechanism. In vitro experiments found that different hydrothermal treatment temperatures affect the formation of ZnO crystals. The crystal diameter of ZnO changes from micron to nanometer at different temperatures, and the crystal morphology also changes. In vitro, scanning electron microscopy, energy dispersive spectrometry, and real-time polymerase chain reaction results show that ZnO nanocrystal can promote the attachment and proliferation of oral epithelial cells on the surface of zirconia by promoting the binding of laminin 332 and integrin β4, regulating the PI3K/AKT pathway. In vivo, ZnO nanocrystal ultimately promotes the formation of soft tissue seals. Collectively, ZnO nanocrystal can be synthesized on a zirconia surface by hydrothermal treatment. It can help to form a seal between the implant abutment and surrounding soft tissue. This method is beneficial to the long-term stability of the implant and also can be applied to other medical fields.

Cost-Effective and Efficient Cool Nanopigments Based on Oleic-Acid-Surface-Modified ZnO Nanostructured

In this paper, as-synthesized and oleic acid (OA)-surface-treated zinc oxide (ZnO) nanocrystals were successfully synthesized and investigated for cool-nanopigment applications. ZnO nanocrystals were synthesized using the thermal decomposition method. The OA-surface-treated ZnO sample was obtained with an OA:ZnO ratio of 1:1. The structural, optical and morphological properties of the samples were characterized via X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV-VIS-NIR diffused reflectance spectroscopy (DRS) and field-emission scanning electron microscopy (FE-SEM) techniques. ZnO nanocrystals possess a well-known zincate phase of ZnO, as confirmed for the as-synthesized sample with a reduction in the integrity of the ZnO crystalline structure upon the application of the OA coating. XRD peaks broadening and decreasing in crystallite size were obtained upon the surface modification of the ZnO by OA. The average crystallite size decreased from 31.5 to 17.4 nm, and the surface area changed from 23.37 to 7.48 m2/g upon OA treatment. These changes were attributed to the well-capping of the ZnO nanoparticles by OA, and, furthermore, OA increased the dispersion of the nanoparticles. The optical band gap of the investigated samples demonstrated a blue shift from 3.06 eV to 3.22 eV upon treatment. Both samples showed high NIR reflectance (RNIR∗) values, which makes them well qualified for use as cool nanopigments. Additionally, the as-synthesized sample showed an RNIR∗ value higher than that of the treated sample.

Crystalline native defects in ZnO analyzed by photoluminescence applying Maxwell-Boltzmann statistics in the visible region

Zinc oxide (ZnO (s) ) is prepared by Chemical Bath Deposition. This manuscript continues with previous research examining the Photoluminiecence at UV-Vis-region. According to emission bands situated at Vis-region by means of Photoluminescence, green (GE) and yellow emission (YE) bands are discussed, which are associated with native intrinsic crystalline defects. The Photoluminescence dependence with the trap density and the surface recombination velocity in the light of the Maxwell-Boltzmann theoretical model (MBM) results associated with the electronic transitions related to the native intrinsic defects situated at9 Vis-region are investigated. The trap density (cm -1 ) of nanocrystals located at range ~8.9-9.9 An approximate a theoretical-experimental kinetic model is presented, considering that the coordination complex ion is a key parameter in the crystal growth of ZnO (s) nanocrystals. The optimized geometry of [Zn(NH 3 ) 4 ] 2+ molecule was obtained with the DFT method using the functional of H-GGA B3LYP.

Influence of surface modification by organic molecules on optical properties of Eu3+-doped ZnO nanocrystals

We have fabricated Eu3+-doped ZnO (ZnO:Eu) nanocrystals (NCs) surface-modified with organic molecules such as dodecylamine (DDA) and tri-n-octylphosphine oxide (TOPO) and have studied their optical properties. In the ZnO:Eu NCs without surface modification, strong broad photoluminescence (PL) band due to surface defects is observed, so the Eu3+ PL peaks are not observed because they are covered by the strong surface-defect PL band. In the DDA-capped ZnO:Eu NCs, the Eu3+ PL and the exciton PL are observed because of suppression of the surface-defect PL caused by the inactivation of the surface defects. Contrary to expectations, the surface modification with TOPO suppressed not only the surface-defect PL but also the exciton PL. As a result, the ZnO:Eu NCs with red PL due to the Eu3+ ions have been successfully prepared. We discuss the influence of surface modification by DDA and TOPO on optical properties.

Dual Drug Loaded Nanotheranostic Platforms as a Novel Synergistic Approach to Improve Pancreatic Cancer Treatment

AbstractThis study focuses on the development of theranostic, dual drug‐loaded nanocarriers to propose a proof‐of‐principle therapeutic approach in the treatment of pancreatic ductal adenocarcinoma (PDAC). The nanoconstructs consist of a core of zinc oxide nanocrystals doped with gadolinium, useful as a potential contrast agent in magnetic resonance imaging applications. After functionalizing their surface with amino‐propyl groups, the physical adsorption of two hydrophobic drugs is performed: Vismodegib and Sorafenib. Their synergistic use might improve PDAC treatment and stroma depletion when co‐delivered in the tumor microenvironment for future in vivo applications. To enhance the nanoconstructs’ biostability, the ensemble is coated by a lipid bilayer and a tumor targeting peptide is incorporated on the outer shell surface. As a first proof of concept, the resulting nanoconstructs are tested against two pancreatic cancer cell lines, showing a modest increase in treatment efficacy compared to the free drug counterparts and proving to spare healthy pancreatic cells. In a second testing set, the dual‐drug loaded nanoconstructs are tested on both cell lines previously sensitized to a first‐line chemotherapeutic drug, Gemcitabine, showing an improved treatment response. From these preliminary results, the nanotheranostic platforms might constitute a good starting point for future PDAC therapy and diagnosis studies.

Nanocomposite zinc oxide@ γ-linolenic acid-canagliflozin-fucoxanthin and/or γ-radiation perturbs key metabolic effectors and suppresses the proliferation of breast cancer cells in vitro

Breast cancer is a complicated illness with a variety of biological and clinical traits. Traditional cancer treatments have come under fire for their wide range of adverse effects and ineffective tumor eradication. The current study aims to assess the cytotoxic potential of multifunctional-targeted nanocomposites zinc [email protected] γ-linolenic acid (γ-LA)-canagliflozin (CAN)-fucoxanthin (FX) (ZLCF) and/or γ-radiation (4Gy) against breast cancer cells (BCCs). The well-dispersed ZnO nanocrystals were synthesized using the wet chemical method. ZnO nanoparticles were coated with γ-LA-CAN-FX conjugated with folic acid and were characterized by various assays. The antimicrobial effect was tested. Furthermore, the cytotoxicity assay, stability, release, selective delivery and cellular uptake of ZLCF in BCCs were performed. Moreover, the anticancer effect of ZLCF was examined on various metabolic effectors linked with cell cycle distribution and apoptotic analysis. The pure ZnO NPs and ZLCF show a resilient anti-bacterial action against E. coli at 20 μg/mL. The data showed a significant anticancer effect of ZLCF and/or 4Gy on BCCs compared with untreated cancer cells due to modulation of metabolic effectors that led to arrest in the sub-G1 and G0/1 phases related with apoptotic of BCCs. It could be concluded that ZLCF nanocomposite succeeded in suppressing of BCCs proliferation and enhanced the radiosensitization. Thus, it could be recommended that ZLCF nanocomposite with radiotherapy be a helpful therapeutic agent for treating breast cancer and would deserve further attention and research onwards.

Structural, morphological and dielectric behavior of Mg, Al, Ga/Mg and Al/Mg-doped ZnO nanoparticles: A comparative study

This study includes the preparation of pure and doped-ZnO nanoparticles using sol–gel method. In this study, the impact of dopant ions on structural and dielectric behavior of ZnO nanocrystal was studied using X-ray diffraction, field emission scanning electron microscopy and impedance analyzer, respectively. The XRD study confirmed the wurtzite structure of pure and doped-ZnO nanoparticles. The crystallite size varied from 41.96 nm to 27.97 nm. Also, the microstructure of prepared samples shows formation of spherical shaped grains. In addition, the high value of dielectric constant of Zn0.96Al0.04O sample as compared to other samples may be attributed to polar –OH groups on its crystalline surface. Moreover, the variation of impedance (Z′) with frequency and Nyquist plots indicate the high value of impedance for Zn0.97Mg0.03O and Zn0.96Al0.04O nanoparticles at low frequency range and a sharp decrease at higher frequency range. The observed impedance behavior of prepared nanoparticles was in good agreement with their ac conductivities. The higher value of dielectric constant leads to more capacitance which will help in storing more energy. Thus, it may be concluded that Zn0.96Al0.04O nanoparticles can have advantages for data storage applications in electronic devices.

Design of Biodiesel Reactor Using Nanocatalyst ZnO From Castor Oil

Mass transfer during the reaction process is limited in industrial biodiesel manufacture. Therefore, to overcome this problem, a reactor from castor oil transesterified using ZnO nanocatalyst was designed. ZnO can be used as a catalyst for biodiesel production due to the nature of ZnO which has high catalytic activity, low material costs and is environmentally friendly. This study aims to design a design for the manufacture of zinc oxide (ZnO) nanocrystals using a continuous stirred tank reactor (CSTR) reactor. By giving data on incoming feedstock and product flow produced by the reactor, mass balance calculations were used in this study as a benchmark to determine whether the reactor was operating appropriately. Additionally, using Microsoft Excel, manual calculations were done for the reactor design and agitator design employed in the reactor. According to calculations used in reactor design, the reactor has a volume of 1967.78 liters, a vessel diameter of 44.77 inches, a height of 19.25 inches, and a thickness of 44.98 inches. The reactor is equipped in one stirrer with a power on a typical 10 hp agitator motor, turbulent agitator flow conditions exist.

Electrochemically Stable Ligands of ZnO Electron-Transporting Layers for Quantum-Dot Light-Emitting Diodes

Thin films of ZnO nanocrystals are actively pursued as electron-transporting layers (ETLs) in quantum-dot light-emitting diodes (QLEDs). However, the developments of ZnO-based ETLs are highly engineering oriented and the design of ZnO-based ETLs remains empirical. Here, we identified a previously overlooked efficiency-loss channel associated with the ZnO-based ETLs: i.e., interfacial exciton quenching induced by surface-bound ethanol. Accordingly, we developed a general surface-treatment procedure to replace the redox-active surface-bound ethanol with electrochemically inert alkali carboxylates. Characterization results show that the surface treatment procedure does not change other key properties of the ETLs, such as the conductance and work function. Our single-variable experimental design unambiguously demonstrates that improving the electrochemical stabilities of the ZnO ETLs leads to QLEDs with a higher efficiency and longer operational lifetime. Our work provides a crucial guideline to design ZnO-based ETLs for optoelectronic devices.

Self-Organization Effects of Thin ZnO Layers on the Surface of Porous Silicon by Formation of Energetically Stable Nanostructures.

The formation of complex surface morphology of a multilayer structure, the processes of which are based on quantum phenomena, is a promising domain of the research. A hierarchy of pore of various sizes was determined in the initial sample of porous silicon by the atomic force microscopy. After film deposition by spray pyrolysis, ZnO nanoclusters regularly distributed over the sample surface were formed. Using the electron paramagnetic resonance (EPR) method it was determined that the localization of paramagnetic centers occurs more efficiently as a result of the ZnO deposition. An increase in the number of deposited layers, leads to a decrease in the paramagnetic center relaxation time, which is probably connected with the formation of ZnO nanocrystals with energetically stable properties. The nucleation and formation of nanocrystals is associated with the interaction of particles with an uncompensated charge. There is no single approach to determine the mechanism of this process. By the EPR method supplemented with the signal cyclic saturation, spectral manifestations from individual centers were effectively separated. Based on electron paramagnetic resonance and photoluminescence studies it was revealed that the main transitions between energy levels are due to oxygen vacancies and excitons.

Synthesis of nano-ZnO by chemical method and its characterization

Nanocrystals of ZnO were prepared by chemical method using Zn (II) acetate and potassium hydroxide as the starting materials and methanol as solvent. The material were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), electron diffraction analysis (EDS), UV–Visible spectroscopy, Dynamic light scattering analysis (DLS) and Fourier transform spectroscopy (FTIR) techniques. The resultant results indicated that the obtained ZnO material was in nano-dimension and possess pure wurtzite hexagonal phase.

Synthesis by soft chemistry of size-controlled zinc oxide (ZnO) nanocrystals for antimicrobial applications

This work focuses on the synthesis of ZnO nanoparticles (NPs) by the sol-gel method for antimicrobial applications. The influence of synthesis parameters on the size of NPs is discussed. The addition of water and an alcoholamine (Monoethanolamine MEA) during the synthesis made possible the crystallization of ZnO at low temperature (<110°C). Our experiments have also shown that these reagents exert an influence on the size of the NPs. The NPs after precipitation are recovered in the form of powders then characterized by different techniques: X-ray diffraction (XRD) and Raman spectroscopy. The crystalline domain size are calculated from Scherrer’s formula. The antimicrobial potential of these NPs has been studied. The technique applied for this evaluation consists in estimating the minimum inhibitory concentration (MIC) of the NPs by measuring the evolution of the optical density of the bacteria over time. The results showed that the synthesized ZnO NPs show efficacy on the Escherichia coli bacteria.