Synthesis and characterization of nearly monodisperse …
Heterogeneous photo-catalysis is an advanced oxidation process (PAO), which has been the subject of numerous studies and applications, particularly using the commercial oxide of TiO2 (P25, Evonik). Zinc oxide (ZnO) has often been considered a valid alternative to TiO2 due to its good opto-electronic, catalytic and photochemical characteristics along with its low cost. In order to improve the photocatalytic performance of ZnO for practical applications, various types of synthetic approaches have been developed, including, among others, the hydrothermal / solvothermal growth method, sol-gel method, ultrasonic assisted method, deposition chemistry in vapor phase, etc. with the aim of preparing ZnO particles with different sizes and morphologies. However, all of these methods require relatively severe reaction conditions such as high temperature, sophisticated techniques, high purity of gases, adjustable gas flow, expensive raw materials, etc. Therefore, it is important to find a simple and cost-effective method for the synthesis of crystalline nano-particles of ZnO. For this reason, in the present work, the ZnO has been synthesized by three different procedures: conventional aqueous precipitation method, hydrothermal method (H) and microwave assisted method (MW). In all three processes, the same material is obtained, hydrocincite [Zn5(CO3) 2(OH)6], which evolves to crystalline ZnO after calcination thermal treatments. We investigated the effect of the calcination temperature, at the same time (2 h), on the optical, textural and structural properties. Photo-catalytic studies were performed using two selected substrates, Methyl Orange and Phenol, as toxic model substrates (one colorant and the other transparent). The catalysts prepared were characterized by several techniques: DRX, SBET, FE-SEM, TEM and UV-Vis (in diffuse reflectance mode).From the results of XRD, it has been possible to establish that a minimum difference between the relative intensities of exposed faces (I100 and I002) is a crucial factor to obtain good photocatalytic properties. This minimum difference is achieved, in our cases by thermal treatments of calcination at 400ºC, 2 h. When this temperature is chosen, there is no appreciable variation between the photocatalytic activities of the oxides of zinc obtained by the three processes, and there are small differences depending on the nature of the substrate chosen, which can be attributed to the textural differences between the oxides. In any case, the obtained zinc oxides show, for each substrate, photo-catalytic activities in the UV that are superior to those presented by the widely used commercial oxide TiO2 (P25) used as reference.
Green Synthesis of Metallic Nanoparticles via ..
Cecile Reynaud has her expertise in the synthesis and chemical physics of nanomaterials. Her work has mainly dealt with silicon nanocrystals and aligned carbon nanotubes. She was for 15 years at the head of the Laboratory of Nanometric Assemblies (LEDNA) in the fundamental research division of Saclay CEA center. The LEDNA group follows the "bottom-up" approach of nanosciences. It develops its own synthesis methods and obtains nanostructured materials with well-controlled characteristics. The applications are relevant for energy, health, environmental issues and the development of composite materials. The group also develop the up-scaling of its processes to allow their industrial transfer.
Prof. Nana Zhao obtained her B. S. in Applied Chemistry in 2003 from Shandong University, and Ph.D. in Physical Chemistry in 2008 from Peking University. From 2008 to 2010, she worked as a Postdoc Fellow in Department of Polymer and Material Chemistry at the University of Toronto, Canada. After another two years’ post-doctoral work in Division of Materials Science at Lawrence Berkeley National Laboratory, she joined Beijing University of Chemical Technology in 2012. She has published over 20 publications in well-known international journals such as Chem. Soc. Rev., Angew. Chem. Int. Ed., Nano Lett., and Adv. Mater. et al. Prof. Zhao has her expertise in strategic design, controlled synthesis, and biomedical applications of organic/inorganic nanohybrids, including diagnosis of diseases, gene delivery, controlled drug-release, and imaging. Integrating the control over morphology, surface functionalization, and self-assembly strategies, the performance of nanohybrids could be improved further.
Journal of Nanoscience and Nanotechnology
Patients with non-small cell lung cancer (NSCLC) having a sensitizing mutation in the endothelial growth factor receptor (EGFR) gene, are susceptible to EGFR tyrosine kinase inhibitor, Erlotinib. Erlotinib is currently the standard of care in treatment of advanced and/or metastatic NSCLC. Although Erlotinib is available as an oral tablet, to further improve its clinical benefits, local delivery of Erlotinib to the tumor(s) in the lungs can be an innovative strategy. Therefore, the aim of this study is fabrication of an Erlotinib-loaded SLN formulation for developing a dry powder inhaler (DPI) for direct delivery of Erlotinib to the lungs. Optimal compritol/poloxamer 407 SLNs were produced in sub-100 nm spherical shape and showed an encapsulation efficiency of 78.21% for Erlotinib. MTT assay and DAPI staining showed that the SLN formulation enhanced the cytotoxicity of Erlotinib in A549 model NSCLC cell line. The SLNs were successfully spray dried into microparticles (1-5 µm) with mannitol as a carrier. The powder had suitable flowability and aerodynamic behavior and could thus theoretically provide a deep inhalation pattern, as assessed by Carr' Index, Hausner ratio and Next Generation Impactor (NGI). Taken together, the fabricated SLNs can be promising candidates for improving the efficacy of Erlotinib in NSCLC treatment.
reports on Cu nanocrystal synthesis with.
The administration of nanoparticles to tumors followed by alternating magnetic field application was shown to efficiently destroy tumors both preclinically and clinically, especially glioma. However, antitumor efficacy remains suboptimal and requires further improvements. We therefore developed a new type of nanoparticles synthesized by magnetotactic bacteria called magnetosomes. Due to their chain arrangement that leads to uniform distribution, ferrimagnetic properties that enhance their heating power and to a controlled release of endotoxins that attract polynuclearneutrophiles, we show that chains of magnetosomes achieve full destruction of intracranial U87-Luc glioma tumors under AMF application in 40% of treated mice using a rather low quantity of magnetosomes administered of 13 µg of magnetosomes per mm3 of tumor. By contrast, under the same treatment conditions, signs of antitumor activity are not observed with chemically synthesized nanoparticles currently used in the magnetic hyperthermia treatment of tumors. It also appears that full glioma destruction is achieved when magnetosomes occupy only 10% of the whole tumor volume, which suggests the involvement of an indirect mechanism of tumor destruction, which is desired for the treatment of infiltrating tumors, such as glioma, for which whole tumor coverage by nanoparticles can hardly be achieved.