Photocatalytic Degradation of Methylene Blue and Metanil Yellow Dyes Using Green Synthesized Zinc Oxide (ZnO) Nanocrystals

In this work, ZnO nanocrystals (NCs) have been effectively synthesized by a simple, efficient and cost-effective method using coconut husk extract as a novel fuel. The synthesized NCs are characterized by UV-Vis, XRD, FT-IR, SEM, EDX, Raman and PL studies. The obtained ZnO were found to be UV-active with a bandgap of 2.93 eV. The X-ray diffraction pattern confirms the crystallinity of the ZnO with hexagonally structured ZnO with a crystallite size of 48 nm, while the SEM analysis reveals the hexagonal bipyramid morphology. Photocatalytic activities of the synthesized ZnO NCs are used to degrade methylene blue and metanil yellow dyes.

Oxidation of MBE-Grown ZnTe and ZnTe/Zn Nanowires and Their Structural Properties

Results of comparative structural characterization of bare and Zn-covered ZnTe nanowires (NWs) before and after thermal oxidation at 300 °C are presented. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, and Raman scattering not only unambiguously confirm the conversion of the outer layer of the NWs into ZnO, but also demonstrate the influence of the oxidation process on the structure of the inner part of the NWs. Our study shows that the morphology of the resulting ZnO can be improved by the deposition of thin Zn shells on the bare ZnTe NWs prior to the oxidation. The oxidation of bare ZnTe NWs results in the formation of separated ZnO nanocrystals which decorate crystalline Te cores of the NWs. In the case of Zn-covered NWs, uniform ZnO shells are formed, however they are of a fine-crystalline structure or partially amorphous. Our study provides an important insight into the details of the oxidation processes of ZnTe nanostructures, which could be of importance for the preparation and performance of ZnTe based nano-devices operating under normal atmospheric conditions and at elevated temperatures.

Cu-Doped-ZnO Nanocrystals Induce Hepatocyte Autophagy by Oxidative Stress Pathway

As a novel nanomaterial for cancer therapy and antibacterial agent, Cu-doped-ZnO nanocrystals (CZON) has aroused concern recently, but the toxicity of CZON has received little attention. Results of hematology analysis and blood biochemical assay showed that a 50 mg/kg dosage induced the increase in white blood cells count and that the concentration of alanine aminotransferase (ALT), superoxide dismutase (SOD), catalase (CAT), and Malonaldehyde (MDA) in the serum, liver, and lungs of the CZON group varied significantly from the control mice. Histopathological examinations results showed inflammation and congestion in the liver and lung after a single injection of CZON at 50 mg/kg. A transmission electron microscope (TEM) result manifested the autolysosome of hepatocyte of mice which received CZON at 50 mg/kg. The significant increase in LC3-II and decrease in p62 of hepatocyte in vivo could be seen in Western blot. These results indicated that CZON had the ability to induce autophagy of hepatocyte. The further researches of mechanism of autophagy revealed that CZON could produce hydroxyl radicals measured by erythrocyte sedimentation rate (ESR). The result of bio-distribution of CZON in vivo, investigated by ICP-OES, indicated that CZON mainly accumulated in the liver and two spleen organs. These results suggested that CZON can induce dose-dependent toxicity and autophagy by inducing oxidative stress in major organs. In summary, we investigated the acute toxicity and biological distribution after the intravenous administration of CZON. The results of body weight, histomorphology, hematology, and blood biochemical tests showed that CZON had a dose-dependent effect on the health of mice after a single injection. These results indicated that CZON could induce oxidative damage of the liver and lung by producing hydroxyl radicals at the higher dose.