Facile microwave-assisted synthesis of titanium dioxide decorated graphene nanocomposite for photodegradation of organic dyes

An efficient and facile method was adopted to prepare TiO2-graphene (TG) nanocomposites with TiO2 nanoparticles uniformly distributed on graphene. By adjusting the amount of TiO2 precursor, both high and low dense TiO2 nanoparticles on graphene were effectively attained via electrostatic attraction between graphene oxide sheets and TiO2 nanoparticles. The prepared nanocomposites were characterized by various characterization techniques. The TG nanocomposite showed an excellent activity for the photodegradation of the organic dyes such as methylene blue (MB) and rose bengal (RB) under ultra violet (UV) light irradiation. The TG nanocomposite of TG 2.5 showed better photocatalytic performance than bare TiO2 nanoparticles and other composites. The enhanced activity of the composite material is attributed to the reduction in charge recombination and interaction of organic dyes with graphene. The decrease in charge recombination was evidenced from the photoluminescence (PL) spectra. The observed results suggest that the synthesized TG composites have a potential application to treat the industrial effluents, which contain organic dyes

Anti-inflammatory and immune-modulating effects of rice callus suspension culture (RCSC) and bioactive fractions in an in vitro inflammatory bowel disease model

Background Rice Callus Suspension Culture (RCSC) has been shown to exhibit potent antiproliferative activity in multiple cancer cell lines. RCSC and its bioactive compounds can fill the need for drugs with no side effects. Hypothesis/Purpose The anti-inflammatory potential of RCSC and its bioactive fractions on normal colon epithelial cell lines, was investigated. Study Design Three cell lines, InEpC, NCM356 and CCD841-CoN were treated with proinflammatory cytokines followed by RCSC. Cytoplasmic and nuclear ROS were assayed with fluorescent microscopy and flow cytometer. Expression analysis of immune-related genes was performed in RCSC-treated cell lines. RCSC was fractionated using column chromatography and HPLC. Pooled fractions 10-18 was used to test for antiproliferative activity using colon adenocarcinoma cell line, SW620 and anti-inflammatory activity using CCD841-CoN. Mass spectrometric analysis was performed to identify candidate compounds in four fractions. Results RCSC treatment showed differential effects with higher cytoplasmic ROS levels in NCM356 and CCD841-CoN and lower ROS levels in InEpC. Nuclear generated ROS levels increased in all three treated cell lines. Flow cytometry analysis of propidium iodide stained cells indicated mitigation of cell death caused by inflammation in RCSC treated groups in both NCM356 and CCD841-CoN. Genes encoding transcription factors and cytokines were differentially regulated in NCM356 and CCD841-CoN cell lines treated with RCSC which provided insights into possible pathways. Analysis of pooled fractions 10-18 by HPLC identified 8 peaks. Cell viability assay with fractions 10-18 using SW620 showed that the number of viable cells were greatly reduced which was similar to 6X and 33X RCSC with very little effect on normal cells which similar to 1X RCSC. RCSC fractions increased nuclear and cytoplasmic ROS versus both untreated and inflammatory control. Analysis of four fractions by mass spectrometry identified 4-deoxyphloridzin, 5’-methoxycurcumin, piceid and lupeol as candidate compounds which are likely to be responsible for the antiproliferative, anti-inflammatory and immune-regulating properties of RCSC. Conclusion RCSC and its fractions showed anti-inflammatory activity on inflamed colon epithelial cells. Downstream target candidate genes which are likely to mediate RCSC effects were identified. Candidate compounds responsible for the antiproliferative and anti-inflammatory activity of RCSC and its fractions provide possible drug targets

Micro-Raman Scattering of Nanoscale Silicon in Amorphous and Porous Silicon

The size effect of nanoscale silicon in both amorphous and porous silicon was investigated with micro-Raman spectroscopy. Silicon nanostructures in amorphous silicon were deposited on quartz substrates by plasma enhanced chemical vapor deposition (PECVD) with deposition powers of 15, 30 and 50 W. Micro-Raman spectra of the nanostructured silicon show the T2g Raman active mode shifting from the 521 cm-1 crystalline Si Raman line to 494, 499 and 504 cm-1 as deposition power increased. Large Raman mode shifts, up to 27 cm-1 and broadening up to 23 cm-1 of the T2g Raman-active mode is attributed to a phonon confinement effect. The analysis of micro-Raman scattering data is useful to understand the role of deposition condition of the silicon sample. In addition, micro-Raman scattering intensity of porous silicon prepared using various current densities such as 10, 50 and 125 mA/cm2 has also been investigated. The effect of phonon confinement on the nanoscale porous silicon has been quantified. The relationship between Raman shift and stress on the porous silicon has been evaluated

Micro-Raman scattering of nanoscale silicon in amorphous and porous silicon

The size effect of nanoscale silicon in both amorphous and porous silicon was investigated with micro-Raman spectroscopy. Silicon nanostructures in amorphous silicon were deposited on quartz substrates by plasma enhanced chemical vapor deposition (PECVD) with deposition powers of 15, 30 and 50 W. Micro-Raman spectra of the nanostructured silicon show the T2g Raman active mode shifting from the 521 cm−1 crystalline Si Raman line to 494, 499 and 504 cm−1 as deposition power increased. Large Raman mode shifts, up to 27 cm−1 and broadening up to 23 cm−1 of the T2g Raman-active mode is attributed to a phonon confinement effect. The analysis of micro-Raman scattering data is useful to understand the role of deposition condition of the silicon sample. In addition, micro-Raman scattering intensity of porous silicon prepared using various current densities such as 10, 50 and 125 mA/cm2 has also been investigated. The effect of phonon confinement on the nanoscale porous silicon has been quantified. The relationship between Raman shift and stress on the porous silicon has been evaluated

ZnO/Graphene Composite from Solvent-Exfoliated Few-Layer Graphene Nanosheets for Photocatalytic Dye Degradation under Sunlight Irradiation

ZnO/graphene nanocomposites were prepared using a facile approach. Graphene nanosheets were prepared by ultrasonication-based liquid phase exfoliation of graphite powder in a low boiling point organic solvent, 1,2-Dichloroethane, for the preparation of ZnO/graphene nanocomposites. Structural properties of the synthesized ZnO/graphene nanocomposites were studied through powder XRD and micro-Raman analysis. The characteristic Raman active modes of ZnO and graphene present in the micro-Raman spectra ensured the formation of ZnO/graphene nanocomposite and it is inferred that the graphene sheets in the composites were few layers in nature. Increasing the concentration of graphene influenced the surface morphology of the ZnO nanoparticles and a flower shape ZnO was formed on the graphene nanosheets of the composite with high graphene concentration. The efficiencies of the samples for the photocatalytic degradation of Methylene Blue dye under sunlight irradiation were investigated and 97% degradation efficiency was observed. The stability of the nanocomposites was evaluated by performing five cycles, and 92% degradation efficiency was maintained. The observed results were compared with that of ZnO/graphene composite derived from other methods