Sensing Properties of NiO Loaded SnO2 Nanoparticles—Specific Selectivity to H2S

NiO-loaded SnO2 powders were prepared involving two chemical procedures. The mesoporous SnO2 support was synthesized by a hydrothermal route using Brij 35 non-ionic surfactant as a template. The nickel loadings of 1 and 10 wt.%. NiO were deposited by the wet impregnation method. The H2S sensing properties of xNiO-(1-x)SnO2 (x = 0, 1, 10%) thick layers deposited onto commercial substrates have been investigated with respect to different potential interfering gases (NO2, CO, CO2, CH4, NH3 and SO2) over a wide range of operating temperatures and relative humidity specific for in-field conditions. Following the correlation of the sensing results with the morphological ones, 1wt.% NiO/SnO2 was selected for simultaneous electrical resistance and work function investigations. The purpose was to depict the sensing mechanism by splitting between specific changes over the electron affinity induced by the surface coverage with hydroxyl dipoles and over the band bending induced by the variable surface charge under H2S exposure. Thus, it was found that different gas-interaction partners are dependent upon the amount of H2S, mirrored through the threshold value of 5 ppm H2S, which from an applicative point of view, represents the lower limit of health effects, an eight-hour TWA

Novel Antitumor Agents Based on Fluorescent Benzofurazan Derivatives and Mesoporous Silica

Two novel fluorescent mesoporous silica-based hybrid materials were obtained through the covalent grafting of [4-hydrazinyl-7-nitrobenz-[2,1,3-d]-oxadiazole (NBDH) and N1-(7-nitrobenzo[c][1,2,5]-oxadiazol-4-yl) benzene-1,2-diamine (NBD-PD), respectively, inside the channels of mesoporous silica SBA-15. The presence of fluorescent organic compounds (nitrobenzofurazan derivatives) was confirmed by infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermal analysis (TG), and fluorescence spectroscopy. The nitrogen physisorption analysis showed that the nitrobenzofurazan derivatives were distributed uniformly on the internal surface of SBA-15, the immobilization process having a negligible effect on the structure of the support. Their antioxidant activity was studied by measuring the ability to reduce free radicals DPPH (free radical scavenging activity), in order to formulate potential applications of the materials obtained. Cytotoxicity of the newly synthesized materials, SBA-NBDH and SBA-NBD-PD, was evaluated on human B16 melanoma cells. The morphology of these cells, internalization and localization of the investigated materials in melanoma and fibroblast cells were examined through fluorescence imaging. The viability of B16 (3D) spheroids after treatment with SBA-NBDH and SBA-NBD-PD was evaluated using MTS assay. The results showed that both materials induced a selective antiproliferative effect, reducing to various degrees the viability of melanoma cells. The observed effect was enhanced with increasing concentration. SBA-NBD-PD exhibited a higher antitumor effect compared to SBA-NBDH starting with a concentration of 125 µg/mL. In both cases, a significantly more pronounced antiproliferative effect on tumor cells compared to normal cells was observed. The viability of B16 spheroids dropped by 40% after treatment with SBA-NBDH and SBA-NBD-PD at 500 µg/mL concentration, indicating a clear cytotoxic effect of the tested compounds. These results suggest that both newly synthesized biomaterials could be promising antitumor agents for applications in cancer therapy

Composite Photocatalysts with Fe, Co, and Ni Oxides on Supports with Tetracoordinated Ti Embedded into Aluminosilicate Gel during Zeolite Y Synthesis

Ti-aluminosilicate gels were used as supports for the immobilization of Fe, Co, and Ni oxides (5%) by impregnation and synthesis of efficient photocatalysts for the degradation of β-lactam antibiotics from water. Titanium oxide (1 and 2%) was incorporated into the zeolite network by modifying the gel during the zeolitization process. The formation of the zeolite Y structure and its microporous structure were evidenced by X-ray diffraction and N2 physisorption. The structure, composition, reduction, and optical properties were studied by X-ray diffraction, H2-TPR, XPS, Raman, photoluminescence, and UV–Vis spectroscopy. The obtained results indicated a zeolite Y structure for all photocatalysts with tetracoordinated Ti4+ sites. The second transitional metals supported by the post-synthesis method were obtained in various forms, such as oxides and/or in the metallic state. A red shift of the absorption edge was observed in the UV–Vis spectra of photocatalysts upon the addition of Fe, Co, or Ni species. The photocatalytic performances were evaluated for the degradation of cefuroxime in water under visible light irradiation. The best results were obtained for iron-immobilized photocatalysts. Scavenger experiments explained the photocatalytic results and their mechanisms. A different contribution of the active species to the photocatalytic reactions was evidenced