ZnO NCs Research Articles

Synthesis and characterization of CMC-wrapped Nano-ZnO for photocatalytic degradation of dye under sunlight

This research work focused on studying the fabrication of biopolymer carboxymethyl cellulose (CMC) wrapped ZnO nano-composite materials (ZnO-CMC NCs) and its applications in the photocatalytic degradation of methylene blue (MB) using under sunlight Irradiation. ZnO-CMC NCs were synthesized by using zinc acetate dihydrate as a precursor under alkaline conditions followed by the addition of capping agent CMC followed by calcination at various temperatures. The materials were characterized by FTIR, UV-Vis and powder XRD studies. The presence of CMC as a capping agent not only facilitated the nucleation and growth of (nanoparticles) NPs but also it provided stability and functionalization to the NPs. The varying calcination temperature played a significant role in influencing the size of NCs during the synthesis process. The crystallite size of ZnO-CMC NCs were found to be 19.5959 nm, 21.2518 nm, 23.5000 nm, 27.5930 nm, 34.9789 nm at 250°C, 350°C, 450°C, 550°C, and 650°C calcinations temperature respectively. It was observed that size increases slightly by increasing the calcination temperature from 250°C to 450°C. However, further increase in calcination temperature increases crystallite size significantly. The degradation of MB dye has been studies under UV-Vis spectrophotometer and it was observed that synthesized ZnO-CMC NCs were very efficient in the photocatalytic degradation of MB under natural sunlight. We believe that, these synthesized CMC-wrapped ZnO NCs will find wide range of photocatalytic applications for the treatment of organic pollutants in various dyes used in the chemical industries.

Control repeatability synthesis of a new structure: nanoyarn in green synthesis of 3D ZnO NCs and its thermal time influence on optical properties

Control repeatability synthesis of a new structure: nanoyarn in green synthesis of 3D ZnO NCs and its thermal time influence on optical properties

On the Fate of Lithium Ions in Sol-Gel Derived Zinc Oxide Nanocrystals.

Among diverse chemical synthetic approaches to zinc oxide nanocrystals (ZnO NCs), ubiquitous inorganic sol-gel methodology proved crucial for advancements in ZnO-based nanoscience. Strikingly, unlike the exquisite level of control over morphology and size dispersity achieved in ZnO NC syntheses, the purity of the crystalline phase, as well as the understanding of the surface structure and the character of the inorganic-organic interface, have been limited to vague descriptors until very recently. Herein, ZnO NCs applying the standard sol-gel synthetic protocol are synthesized with zinc acetate and lithium hydroxide and tracked the integration of lithium (Li) cations into the interior and exterior of nanoparticles by combining various techniques, including advanced solid-state NMR methods. In contrast to common views, it is demonstrated that Li+ ions remain kinetically trapped in the inorganic core, enter into a shallow subsurface layer, and generate "swelling" of the surface and interface regions. Thus, this work enabled both the determination of the NCs' structural imperfections and an in-depth understanding of the unappreciated role of the Li+ ions in impacting the doping and the passivation of sol-gel-derived ZnO nanomaterials.

Facile biosynthesis of Ag–ZnO nanocomposites using Launaea cornuta leaf extract and their antimicrobial activity

The quest to synthesize safe, non-hazardous Ag–ZnO nanoomposites (NCs) with improved physical and chemical properties has necessitated green synthesis approaches. In this research, Launaea cornuta leaf extract was proposed for the green synthesis of Ag–ZnO NCs, wherein the leaf extract was used as a reducing and capping agent. The antibacterial activity of the prepared nanoomposites was investigated against Escherichia coli and Staphylococcus aureus through the disc diffusion method. The influence of the synthesis temperature, pH, and precursor concentration on the synthesis of the Ag–ZnO NCs and antimicrobial efficacy were investigated. The nanoparticles were characterized by ATR-FTIR, XRD, UV–Vis, FESEM, and TEM. The FTIR results indicated the presence of secondary metabolites in Launaea cornuta which assisted the green synthesis of the nanoparticles. The XRD results confirmed the successful synthesis of crystalline Ag–ZnO NCs with an average particle size of 21.51 nm. The SEM and TEM images indicated the synthesized nanoparticles to be spherical in shape. The optimum synthesis conditions for Ag–ZnO NCs were at 70 °C, pH of 7, and 8% silver. Antibacterial activity results show Ag–ZnO NCs to have higher microbial inhibition on E. coli than on S. aureus with the zones of inhibition of 21 ± 1.08 and 19.67 ± 0.47 mm, respectively. Therefore, the results suggest that Launaea cornuta leaf extract can be used for the synthesis of Ag–ZnO NCs.

Enhanced visible light photocatalytic and electrochemical performance of Au modified zinc oxide nanocolumns

Research on the treatment of Acid Black 1 as an azo dye is significant because it is toxic and can have adverse effects on both human health and the ecosystem if not properly treated. The purpose of the research was the preparation and application of Au-ZnO nanocolumn (Au-ZnO NCs) photocatalysts to treat the azo dye Acid Black 1 (AB1) in industrial wastewater when it was exposed to light. The structural, electrochemical, and optical properties of prepared photocatalysts were analyzed. Results of structural analyses using SEM and XRD indicated that the surfaces of the ZnO NCs were successfully coated with Au nanoparticles to produce a large effective surface area. Results of electrochemical experiments showed that depositing conductive Au nanoparticles on the surface of ZnO nanocrystals significantly increased the charge transfer rate, implied a longer lifetime for photo-generated electrons, and increased the separation efficiency of Au-ZnO NCs. Results of optical studies showed that the band gap energies of ZnO NCs and Au-ZnO NCs could be measured to be 3.19 eV and 2.96 eV, respectively, which demonstrated that Au nanoparticles narrowed the band gap energy and caused the absorption to extend to the visible range. Results of studies on photocatalytic degradation showed that Au-ZnO NCs, as opposed to ZnO NCs, removed AB1 photocatalytically more quickly. After 20, 30, 45, 50, and 100 min of visible-light illumination, respectively, the total degradation of AB1 was 10, 25, 100, 125, and 300 mg/L. The Au-ZnO NCs' ability to treat 200 ml of a 100 mg/L AB1 solution using a real industrial wastewater sample and deionized water was studied. The results showed that because there are more pollutants in industrial wastewater, the total treatment of the real sample required more time. The results thus showed that AB1 from actual industrial wastewater was successfully photocatalytically treated in an Au-ZnO NCs photocatalyst.

Efficient degradation of parathion as a pollutant and diazinon as a nerve agent by reaction mechanism with rGO-Co3O4/ZnO nanocomposite photocatalyst

Chemical warfare agents and agricultural pesticides are two of the deadliest and most nefarious pollutants that have devastating impacts on both people and the environment. In this work, the Zinc oxide-decorated cobalt oxide/reduced graphene oxide nanocomposites (rGO-Co3O4/ZnO NCs) was prepared using a two-step hydrothermal method to employed as photocatalyst for degrade parathion (PA) as a pollutant and diazinon (DZ) as a nerve agent simulant in solution. The synthesized NCs was fully characterized using X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, field emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDS) and elemental mapping, thermal gravimetric analysis (TGA), Brunauer–Emmett–Teller/Barrett-Joyner-Halenda (BET/BJH), dynamic light scattering (DLS), UV–vis differential reflectance spectroscopy (UV-DRS) and photoluminescence spectroscopy (PL). The structural features confirmed that the NCs was effectively synthesized, and the optical properties demonstrated that the NCs can be activated by visible light irradiation. The photocatalyst degradation rates of DZ and PA pollutants were respectively 99.6% and 99.8% in 140 min. Response surface methodology was also used to consider the effect of pertinent factors so that some parameters affecting the photocatalytic reaction, such as pH, pesticide concentration, photocatalyst amount, time, and light intensity, were optimized by an experimental design. The results show that adding ZnO nanoparticles (NPs) to the rGO-Co3O4 composition reduced the NCs band gap, which in turn reduced the rate at which photo-generated charges recombined.

Chemiresistive H2S gas sensors based on composites of ZnO nanocrystals and foam-like GaN fabricated by photoelectrochemical etching and a sol-gel method

The structure and morphology of gas-sensitive materials were extremely important to performances of gas sensor. In this work, ZnO nano-crystalline (ZnO NCs) was synthesized on foam-like GaN (F-GaN) by sol-gel method as gas-sensitive materials of H2S gas sensor. When ZnO NCs/F-GaN composite structure was used as gas- sensitive materials for detection of H2S with the concentration of 50 ppm at 220 °C. Importantly, rapid response and recovery time was 78 and 31 s, respectively. Enhancement of the sensing response was mainly attributed to the combination between ZnO NCs and F-GaN. In addition, a multiphase catalytic mechanism was proposed to description the catalytic role of F-GaN in the gas sensing procedure. These results further broadened the application of as-prepared metal oxide semiconductor based GaN in the gas sensing field.

Surface Modification of ZnO Nanocrystals with Conjugated Polyelectrolytes Carrying Different Counterions for Inverted Perovskite Light-Emitting Diodes.

In this work, bromide ions (Br-) on the conjugated polyelectrolytes (CPEs) were converted to tetrafluoroborate (BF4-) or hexafluorophosphate (PF6-) ions through anion exchange. The three CPEs (PFN-Br, PFN-BF4, and PFN-PF6) were utilized solely for surface modification of zinc oxide nanocrystals (ZnO NCs). The ionic groups on CPEs can form permanent dipoles to facilitate charge injection from ZnO NCs to cesium lead bromide (CsPbBr3) NC emitters, therefore promoting luminescent properties of inverted perovskite light-emitting diodes (PeLEDs). The experimental results reveal that ZnO NC films were smoothened by CPEs that allowed flat deposition of the perovskite active layers; moreover, the improved contact between ZnO and perovskite layers was beneficial for reducing leakage current, as verified in the dark current measurement of devices. In addition, the incorporation of CPEs helped to passivate the defects of ZnO NC films and prolong the carrier lifetime of CsPbBr3 NCs. PeLEDs based on different CPEs were then constructed and evaluated. The device based on PFN-Br showed the highest brightness and current efficiency, and the one based on PFN-BF4 exhibited better current efficiency over PFN-Br under the low current density below 160 mA/cm2. This is the first report using fluorene-based CPEs with Br-, BF4-, or PF6- groups to modify the properties of ZnO and CsPbBr3 NCs for the construction of inverted PeLEDs so far. Our experiments explored new kinds of CPEs on the surface modification of ZnO NCs and device performance of PeLEDs.

Effective combination of biocompatible zinc oxide nanocrystals and high-energy shock waves for the treatment of colorectal cancer

BackgroundColorectal cancer (CRC) is the third most diagnosed tumor worldwide, with a very high mortality rate, second only to lung cancer. Current treatments, such as surgery, chemotherapy or radiotherapy, are not effective enough and show several limitations. Among the emerging strategies, nanomedicine offers very powerful tools in cancer treatment. Recently, the combination of nanoparticle antitumor effect with a triggering external stimulation was formulated to boost up the cytotoxic activity.ResultsIn this work, we show the synergistic effect of oleic acid-capped zinc oxide nanocrystals (ZnO NCs) and mechanical high-energy shock waves (SW) in the treatment for CRC cells, in vitro. We tested two different types of ZnO NCs synthetized in our laboratory, the basal undoped ZnO NCs and the iron-doped ones (Fe:ZnO NCs). The presence of the oleic acid capping and the further amino-propyl functionalization guarantee a high colloidal stability to both NCs, while the iron doping confers to Fe:ZnO NCs interesting magnetic properties useful for imaging applications in a clinical perspective. Thus, the iron-doped ZnO NCs are very attractive as potentially theranostic nanoparticles, allowing both stimuli-responsive therapy and magnetic resonance imaging.Importantly, two colon adenocarcinoma cell lines, the HT-29 and the Dukes’ type C Colo 320DM cells were tested, both showing a good bio-tolerance and internalization rates of NCs. With the aim of eradicating the CRC cells, the possible synergism between the undoped/iron-doped ZnO NCs and an external physical stimulus, i.e., high-energy SW, was then here investigated in vitro. We demonstrated that the combined treatment resulted in an augmentation of the antitumor activity, especially for Colo 320DM cells, when compared to controls. Moreover, a repeated and sequenced SW treatment (three times/day, 3SW) after ZnO NCs exposure resulted in a further increased mortality of CRC cells.ConclusionOur work proposes the combination of the cytotoxic activity of ZnO NCs with the SW external stimulation to obtain a booster of the antitumor activity, which warrants further investigation in vivo on CRC as well as on other tumors.Graphical

Green synthesis, phytochemical analysis, characterization and cytotoxic evaluation of gold–zinc oxide nanocomposites using Russian Artemisia leaf extract

An easy and rapid method has been investigated for the biosynthesis of gold–zinc oxide nanocomposites (Au–ZnO NCs) coated with L-lysine using Russian Artemisia leaf extract (RAL). The phytochemical analysis of RAL has shown a high concentration of total phenols and total flavonoids. Characterization of Au–ZnO NCs@L-lysine@RAL was performed using a variety of spectroscopy and microscopy techniques, including Fourier-transform infrared spectroscopy (FT-IR), ultraviolet spectroscopy (UV–Vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS). EDS analysis revealed high-purity gold and zinc in Au–ZnO NCs@L-lysine@RAL. Based on the SEM and TEM results, the size of the nanocomposite was 40 ± 5 nm and it was spherical in shape. The analysis of EDS, FESEM and TEM confirmed the XRD pattern. An MTT assay was used to determine the cytotoxic effect of Au–ZnO NCs@L-lysine@RAL and RAL on A549 lung cancer cells. The results indicated moderate anticancer properties with IC50 values of 1301.11 ± 10.6 and 1005. 6 ± 9.7 μM for RAL and Au–ZnO NCs@L-lysine@RAL, respectively. Au–ZnO​ NCs@L-lysine@RAL, which was synthesized by a simple and rapid green method, could be investigated as a new drug delivery system.

Nanocapsules of ZnO Nanorods and Geraniol as a Novel Mean for the Effective Control of Botrytis cinerea in Tomato and Cucumber Plants.

Inorganic-based nanoparticle formulations of bioactive compounds are a promising nanoscale application that allow agrochemicals to be entrapped and/or encapsulated, enabling gradual and targeted delivery of their active ingredients. In this context, hydrophobic ZnO@OAm nanorods (NRs) were firstly synthesized and characterized via physicochemical techniques and then encapsulated within the biodegradable and biocompatible sodium dodecyl sulfate (SDS), either separately (ZnO NCs) or in combination with geraniol in the effective ratios of 1:1 (ZnOGer1 NCs), 1:2 (ZnOGer2 NCs), and 1:3 (ZnOGer2 NCs), respectively. The mean hydrodynamic size, polydispersity index (PDI), and ζ-potential of the nanocapsules were determined at different pH values. The efficiency of encapsulation (EE, %) and loading capacity (LC, %) of NCs were also determined. Pharmacokinetics of ZnOGer1 NCs and ZnOGer2 NCs showed a sustainable release profile of geraniol over 96 h and a higher stability at 25 ± 0.5 °C rather than at 35 ± 0.5 °C. ZnOGer1 NCs, ZnOGer2 NCs and ZnO NCs were evaluated in vitro against B. cinerea, and EC50 values were calculated at 176 μg/mL, 150 μg/mL, and > 500 μg/mL, respectively. Subsequently, ZnOGer1 NCs and ZnOGer2 NCs were tested by foliar application on B. cinerea-inoculated tomato and cucumber plants, showing a significant reduction of disease severity. The foliar application of both NCs resulted in more effective inhibition of the pathogen in the infected cucumber plants as compared to the treatment with the chemical fungicide Luna Sensation SC. In contrast, tomato plants treated with ZnOGer2 NCs demonstrated a better inhibition of the disease as compared to the treatment with ZnOGer1 NCs and Luna. None of the treatments caused phytotoxic effects. These results support the potential for the use of the specific NCs as plant protection agents against B. cinerea in agriculture as an effective alternative to synthetic fungicides.

Comprehensive study upon physicochemical properties of bio-ZnO NCs

In this study, for the first time, the comparison of commercially available chemical ZnO NCs and bio-ZnO NCs produced extracellularly by two different probiotic isolates (Latilactobacillus curvatus MEVP1 [OM736187] and Limosilactobacillus fermentum MEVP2 [OM736188]) were performed. All types of ZnO formulations were characterized by comprehensive interdisciplinary approach including various instrumental techniques in order to obtain nanocomposites with suitable properties for further applications, i.e. biomedical. Based on the X- ray diffraction analysis results, all tested nanoparticles exhibited the wurtzite structure with an average crystalline size distribution of 21.1 nm (CHEM_ZnO NCs), 13.2 nm (1C_ZnO NCs) and 12.9 nm (4a_ZnO NCs). The microscopy approach with use of broad range of detectors (SE, BF, HAADF) revealed the core–shell structure of bio-ZnO NCs, compared to the chemical one. The nanoparticles core of 1C and 4a_ZnO NCs are coated by the specific organic deposit coming from the metabolites produced by two probiotic strains, L. fermentum and L. curvatus. Vibrational infrared spectroscopy, photoluminescence (PL) and mass spectrometry (LDI-TOF-MS) have been used to monitor the ZnO NCs surface chemistry and allowed for better description of bio-NCs organic coating composition (amino acids residues). The characterized ZnO formulations were then assessed for their photocatalytic properties against methylene blue (MB). Both types of bio-ZnO NCs exhibited good photocatalytic activity, however, the effect of CHEM_ZnO NCs was more potent than bio-ZnO NCs. Finally, the colloidal stability of the tested nanoparticles were investigated based on the zeta potential (ZP) and hydrodynamic diameter measurements in dependence of the nanocomposites concentration and investigation time. During the biosynthesis of nano-ZnO, the increment of pH from 5.7 to around 8 were observed which suggested possible contribution of zinc aquacomplexes and carboxyl-rich compounds resulted in conversion of zinc tetrahydroxy ion complex to ZnO NCs. Overall results in present study suggest that used accessible source such us probiotic strains, L. fermentum and L. curvatus, for extracellular bio-ZnO NCs synthesis are of high interest. What is important, no significant differences between organic deposit (e.g. metabolites) produced by tested strains were noticed—both of them allowed to form the nanoparticles with natural origin coating. In comparison to chemical ZnO NCs, those synthetized via microbiological route are promising material with further biological potential once have shown high stability during 7 days.

Densification of Doped Zinc Oxide Nanocrystal Films via Chemical Bath Infiltration

AbstractColloidal nanocrystals (NCs) hold great promise for the fabrication of thin film devices due to the ability to precisely control their properties and deposit coatings via solution‐based protocols. The role of interfaces, surface defects, and (electrical) connectivity between NCs is a major bottleneck to achieving the desired performance. Here, a novel method to infiltrate and densify nanocrystalline coatings deposited from doped ZnO Ncs is presented. Reduced porosity, enhanced connectivity, and a reduction in surface defects are observed, culminating in vastly improved electrical conductivity. Doped ZnO NCs are processed into an ink and used for thin film deposition. Bulky native ligands are then removed from the film to promote better electrical contact between neighboring NCs and render their surfaces hydrophilic. Afterward, a modified chemical bath deposition (CBD) is adopted to slowly infill the pores between the NCs with pure ZnO via a controlled heterogeneous nucleation process. The optimized CBD avoids excessive surface growth and premature sealing of the film surface, confirmed by combined spectroscopic and morphological characterizations. The resultant hybrid films demonstrate enhanced electrical properties, with conductivity increasing by two orders of magnitude after pore infiltration. These results pave the way to hybrid functional coatings with enriched interparticle communication.

Zinc oxide nanoclusters and their potential application as CH4 and CO2 gas sensors: Insight from DFT and TD-DFT.

We have investigated the adsorption of CH4 and CO2 gases on zinc oxide nanoclusters (ZnO NCs) using density functional theory (DFT). It was found that the CH4 tends to be physically adsorbed on the surface of all the ZnO NCs with adsorption energy in the range -11 to -14 kcal/mol. Even though, the CO2 is favorably chemisorbed on the Zn12 O12 and Zn15 O15 NCs, with adsorption energy about -38 kcal/mol at B3LYP/6-311G(d,p) level of theory. When the CH4 and CO2 gases are adsorbed on the ZnO NCs, their electrical conductivities are decreased, and thus the studied ZnO NCs do not generate an electrical signal in the presence of CH4 and CO2 gases. Interestingly, both pure and gas adsorbed Zn22 O22 NC exhibited more favorable electronic and reactive properties than other NCs. Comparison of the structural, electronic, and optical data predicted by DFT/B3LYP and TD-DFT/CAM-B3LYP calculations with those experimentally obtained show good agreement.

Photocatalytic Oxidative Desulfurization of Thiophene by Exploiting a Mesoporous V2O5-ZnO Nanocomposite as an Effective Photocatalyst

Due to increasingly stringent environmental regulations imposed by governments throughout the world, the manufacture of low-sulfur fuels has received considerable assiduity in the petroleum industry. In this investigation, mesoporous V2O5-decorated two-dimensional ZnO nanocrystals were manufactured using a simple surfactant-assisted sol–gel method for thiophene photocatalytic oxidative desulfurization (TPOD) at ambient temperature applying visible illumination. When correlated to pure ZnO NCs, V2O5-added ZnO nanocomposites dramatically improved the photocatalytic desulfurization of thiophene, and the reaction was shown to follow the pseudo-first-order model. The photocatalytic effectiveness of the 3.0 wt.% V2O5-ZnO photocatalyst was the greatest among all the other samples, with a rate constant of 0.0166 min−1, which was 30.7 significantly greater than that of pure ZnO NCs (0.00054 min−1). Compared with ZnO NCs, and owing to their synergetic effects, substantial creation of hydroxyl radical levels, lesser light scattering action, quick transport of thiophene species to the active recenters, and efficient visible-light gathering, V2O5-ZnO nanocomposites were found to have enhanced photocatalytic efficiency. V2O5-ZnO nanocomposites demonstrated outstanding stability during TPOD. Using mesoporous V2O5-ZnO nanocomposites, the mechanism of the charge separation process was postulated.

Polarization behavior of seedless ZnO nanocolumnars grown by DC-unbalanced magnetron sputtering

The main reason ZnO is attractive for optoelectronic applications is its polarization behavior, which can modify its optical and electronic properties. Here, the polarization of ZnO is highly dependent on its structure and morphology. We study the polarization behavior of ZnO with different structures and morphology. A seedless ZnO nanocolumnars (ZnO NCs) array is fabricated using DC-unbalanced magnetron sputtering (DC-UBMS) with further thermal annealing treatment. Thermal annealing transforms the cone-like ZnO NCs to become rod-like ZnO NCs and significantly reduces the intensity of the crystal plane (002). Thermal annealing changes the polarization, where the annealed-ZnO 600°C exhibits the highest polarization that promotes the increase in lattice constant c and crystallite size. We found a football-like polarization response without saturation polarization, which indicates a presence of leakage current and defect on the samples. Interestingly, a ferroelectric characteristic is observed in annealed-ZnO 800°C with lower polarization than the annealed-ZnO 600°C. The origin of ferroelectricity is further investigated using a comprehensive study. This study provides a new understanding of polarization behavior on ZnO NCs, which is the essential key in designing switchable and non-volatile-based devices.

Photocatalytic degradation activity of goji berry extract synthesized silver-loaded mesoporous zinc oxide (Ag@ZnO) nanocomposites under simulated solar light irradiation

Different approaches have been developed for the synthesis of various nanostructured materials with unique morphologies. This study demonstrated the photocatalytic and antimicrobial abilities of silver-loaded zinc oxide nanocomposites (Ag@ZnO NCs). Initially, ZnO with a unique mesoporous ellipsoidal morphology in the size range of 0.59 ± 0.11 × 0.33 ± 0.09 µm (length × width) was synthesized using aqueous precipitation in a mild hydrothermal condition (80 °C) with the aqueous fruit extract of goji berry (GB) (as an additive) and calcined in air at 200 °C/2 h and 250 °C/3 h. Powder X-ray diffraction (XRD) revealed the formation of a hexagonal phase of the wurtzite (WZ) structure. The average crystallite size of ZnO was 23.74 ± 4.9 nm as calculated using Debye–Scherrer’s equation. It also possesses higher thermal stability with the surface area, pore volume, and pore size of 11.77 m2/g, 0.027 cm3/g, and 9.52 nm, respectively. Furthermore, different mesoporous Ag@ZnO NCs loaded with face-centered cubic (fcc) silver nanoparticles (Ag NPs) in the range of 90–160 nm were synthesized by GB extract as a reducing and capping agent on the surface of ZnO after calcination in air. The immobilization of Ag NPs was confirmed by XRD, X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), FE-transmission electron microscopy (FE-TEM), and energy-dispersive X-ray spectroscopy (EDS). It was found that Ag0.2@ZnO NC (0.2 wt% of Ag) showed excellent photocatalytic degradation of both methylene blue (MB) (cationic) and congo red (CR) (anionic) dyes under simulated solar irradiation. The photocatalytic degradation of 99.3 ± 0.35% MB and 98.5 ± 1.3% CR occurred in 90 and 55 min, respectively, at room temperature by Ag0.2@ZnO NC. Besides, these NCs also showed broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria. The mechanistic concept of generating reactive oxygen species (ROS) by electron and hole charge (e‾/h+) carriers seems to be responsible for the photocatalytic degradation of commercial dyes and antibacterial activities by Ag@ZnO NCs. Thus, these silver-loaded mesoporous ellipsoidal ZnO NCs are promising candidates as photocatalysts for industrial/wastewater treatment as well as in antimicrobial therapeutics.

Nanotechnological engineering of extracellular vesicles for the development of actively targeted hybrid nanodevices

BackgroundWe propose an efficient method to modify B-cell derived EVs by loading them with a nanotherapeutic stimuli-responsive cargo and equipping them with antibodies for efficient targeting of lymphoma cells.ResultsThe post-isolation engineering of the EVs is accomplished by a freeze–thaw method to load therapeutically-active zinc oxide nanocrystals (ZnO NCs), obtaining the so-called TrojanNanoHorse (TNH) to recall the biomimetism and cytotoxic potential of this novel nanoconstruct. TNHs are further modified at their surface with anti-CD20 monoclonal antibodies (TNHCD20) achieving specific targeting against lymphoid cancer cell line. The in vitro characterization is carried out on CD20+ lymphoid Daudi cell line, CD20-negative cancerous myeloid cells (HL60) and the healthy counterpart (B lymphocytes). The TNH shows nanosized structure, high colloidal stability, even over time, and good hemocompatibility. The in vitro characterization shows the high biocompatibility, targeting specificity and cytotoxic capability. Importantly, the selectivity of TNHCD20 demonstrates significantly higher interaction towards the target lymphoid Daudi cell line compared to the CD20-negative cancerous myeloid cells (HL60) and the healthy counterpart (lymphocytes). An enhanced cytotoxicity directed against Daudi cancer cells is demonstrated after the TNHCD20 activation with high-energy ultrasound shock-waves (SW).ConclusionThis work demonstrates the efficient re-engineering of EVs, derived from healthy cells, with inorganic nanoparticles and monoclonal antibodies. The obtained hybrid nanoconstructs can be on-demand activated by an external stimulation, here acoustic pressure waves, to exploit a cytotoxic effect conveyed by the ZnO NCs cargo against selected cancer cells.Graphical

Resonant defect recombination-localized surface plasmon energy transfer and exciton dominated fluorescence in ZnO-Au-ZnO multi-interfaced heteronanocrystals.

The semiconductor-metal heteronanocrystals (HNCs) that possess a perfect epitaxial interface can accommodate novel and interesting physical phenomena owing to the strong interaction and coupling between the semiconductor excitons and metal plasmons at the interface. Here, we fabricate the pyramidal ZnO-Au HNCs and study their unique photophysical properties. Several Au nanospheres are perfectly epitaxially bound with a single ZnO NC owing to the small lattice mismatch between them and there are also ZnO-Au-ZnO sandwiched HNCs. There is a strong coupling between the green defect-associated recombination in the ZnO NC and the localized surface plasmon resonance (LSPR) of the Au nanosphere at the interface of the HNC. This leads to resonant defect recombination-LSPR energy transfer and resultant nearly complete quenching of the green defect luminescence of the ZnO NCs in the HNCs, leaving only the UV exciton luminescence. The lifetimes of both the green and UV emission bands decrease significantly in the ZnO-Au HNCs relative to that of the pure ZnO NCs owing to the combined effect of resonance energy transfer and surface plasmon enhanced radiative transition. The exponent of the luminescence intensity-excitation intensity power function for the green emission band is remarkably smaller than unity, and this suggests that the involved defects have an intermediate concentration.

Green synthesis of sorbus pohuashanensis/aronia melanocarpa extracts functionalized ZnO nanoclusters and their applications

ZnO nanoclusters (ZnO NCs) had been widely utilized in optoelectronics, sensors, dye removal, and antibacterial fields. To reduce or avoid the use of toxic, harmful, and costly chemical reagents, the Sorbus pohuashanensis and Aronia melanocarpa extracts were used to green synthesize ZnO NCs with superior adsorption ability for the organic dyes. The obtained ZnO NCs were characterized by UV–vis spectroscopy (UV–vis), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). TEM and SEM results indicated that the ZnO NCs tended to aggregate into large branching and sheet structures. EDS measurement confirmed the presence of zinc ions on the ZnO NCs. FTIR results revealed that the components of the fruits extracts were bounded on the surface of ZnO NCs. The primary application experiments demonstrated that the Sorbus pohuashanensis and Aronia melanocarpa extracts functionalized ZnO NCs possess effectively removing activity for organic dyes.