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Using the microwave-assisted sol–gel method, Zn- and Cu-doped TiO2 nanoparticles with an anatase crystalline structure were prepared. Titanium (IV) butoxide was used as a TiO2 precursor, with parental alcohol as a solvent and ammonia water as a catalyst. Based on the TG/DTA results, the powders were thermally treated at 500 °C. XRD and XRF revealed the presence of a single-phase anatase and dopants in the thermally treated nanoparticles. The surface of the nanoparticles and the oxidation states of the elements were studied using XPS, which confirmed the presence of Ti, O, Zn, and Cu. The photocatalytic activity of the doped TiO2 nanopowders was tested for the degradation of methyl-orange (MO) dye. The results indicate that Cu doping increases the photoactivity of TiO2 in the visible-light range by narrowing the band-gap energy. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop, characterize and assess the biological activity of a new regenerative 3D matrix with antimicrobial properties, based on collagen (COLL), hydroxyapatite (HAp), β-cyclodextrin (β-CD) and usnic acid (UA). The prepared 3D matrix was characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Microscopy (FT-IRM), Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD). In vitro qualitative and quantitative analyses performed on cultured diploid cells demonstrated that the 3D matrix is biocompatible, allowing the normal development and growth of MG-63 osteoblast-like cells and exhibited an antimicrobial effect, especially on the Staphylococcus aureus strain, explained by the particular higher inhibitory activity of usnic acid (UA) against Gram positive bacterial strains. Our data strongly recommend the obtained 3D matrix to be used as a successful alternative for the fabrication of three dimensional (3D) anti-infective regeneration matrix for bone tissue engineering. [ABSTRACT FROM AUTHOR]

In this work, several nanostructures (nanopowders and nanostars) of undoped and 1%, 3% and 5% europium (Eu3+)-doped ZnO have been synthesized via coprecipitation method using oxalic acid and sodium hydroxide as precipitation agents. Starting from zinc acetate and europium acetate, nanopowders were obtained by coprecipitation with oxalic acid. ZnO based nanostars were synthesized by coprecipitation of Zn2+ and Eu3+ with hydroxide ions (HO-), when zinc chloride and europium acetate were used as reagents. The structure and morphology of the as-prepared ZnO nanopowders and nanostars were investigated by X-ray diffraction and electron microscopy. Only würtzite structure of ZnO was identified in all the samples based on ZnO. Transmission electron microscopy (TEM) investigations have shown an average particle÷crystallite size range from 23 to 29 nm and polyhedral and spherical morphology with tendency to form aggregates for nanopowders. Cytotoxicity tests on MG-63 cell lines was also performed. Photocatalytic activity of ZnO nanopowders have reached higher values compared to ZnO nanostars. The photocatalytic test indicates that the ZnO nanopowders have better activity than the nanostars, most probably because of the higher specific surface. Doping the ZnO with Eu2O3 does not seem to alter it in a decisive manner. The toxicity results indicated that ZnO nanoparticles (NPs) high toxicity on tumoral cells is also induced by particle size and, consequently, the dissolution of Zn2+ ions is dependent on the size of the particles, increasing with the particles size.

In this study, MCM-41 mesoporous silica nanoparticles (NPs) and MCM-41÷Fe3O4 mesoporous silica NPs were prepared by sol-gel method using CTAB (cetyltrimethylammonium bromide) as template and TEOS (tetraethyl orthosilicate) as silica precursor in order to use these materials as drug delivery system (DDS) for different biologically active agents. The MCM-41 and MCM-41÷Fe3O4 mesoporous silica NPs were characterized using specific physico-chemical methods [transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption and desorption studies - BET (Brunauer-Emmett-Teller) method, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy], while the release studies were done by a high-performance liquid chromatography (HPLC)-modified method. The pH dependence of the delivery of folic acid from the mesoporous structures was analyzed and found that the release is pH sensitive. The lower delivery at strongly acid pH comparing with neutral/slightly alkaline pH could be beneficial because in stomach the folic acid can be destroyed.