Enhanced antifungal activity of fluconazole conjugated with Cu-Ag-ZnO nanocomposite.

Cu-Ag-ZnO nanocomposite (NC) has been successfully synthesized by mechanical alloying the Cu, Zn and Ag powder mixture under Ar atmosphere within 4 h of milling. The nanocomposite is then conjugated with the antifungal drug fluconazole by adding 5 wt% powdered drug to the NC and mechanical alloying the total powder mixture for one more hour. The Rietveld refinement of XRD data and FTIR spectrum analyses reveal the detailed structural and microstructural characterizations of the nanocomposite-drug conjugate (NC-DC). Presence of Cu, Ag, ZnO and drug in the 5 h milled powder are confirmed by analyzing TEM images and FESEM-EDS spectrum. Results obtained from FESEM and TEM images reveal the measure of particle size of the nanocomposite-drug conjugate and it agrees well with the crystallite size obtained from the Rietveld refinement. A significant antifungal activity of NC-DC against Candida sp. fungi has been revealed using disk agar diffusion method. Minimum inhibitory concentration (MIC) test confirms that NC-DC with only 5 wt% fluconazole produces similar antifungal activity of the pure (100 wt%) and conventional fluconazole. Thus, the conjugation of conventional drug to a nanocomposite results in enhancement of drug efficiency by a factor 20 folds. This is very important, particularly, for those antibiotics which are very effective in controlling several epidemic diseases but show intense side effects when used at higher dose and/or for a longer duration.

Microstructure characterization of biocompatible heterojunction hydrogen titanate-Ag2O nanocomposites for superior visible light photocatalysis and antibacterial activity.

Hydrogen trititanate (H2Ti3O7·2H2O) and hydrogen trititanate/Ag2O hybrid nanocomposites (NCs) with novel structure have been synthesized by a simple solvothermal route followed by Na+/H+ ion-exchange. Growths of hydrogen trititanate with nanofiber (HTNF) and nanotube (HTNT) morphologies and hydrogen trititanate-Ag2O (HTFAG and HTTAG) nanocomposites have been tailored by controlling the solvent media. Detailed microstructure characterization of all these samples have been carried out by Rietveld refinement of XRD data and analyzing FESEM/HRTEM micrographs and FTIR spectra. Band gap energies of all these semiconducting samples are obtained from UV-Vis absorption spectra. Both HTFAG and HTTAG NCs exhibit enhanced photocatalytic degradation of organic pollutant (Congo red dye) under visible light, in comparison to HTNF and HTNT respectively due to the formation of a heterojunction between H2Ti3O7·2H2O and Ag2O, which is supported by photoluminescence spectroscopy. HTFAG and HTTAG NCs also show superior antibacterial activity against both gram-negative (Escherichia coli) and gram-positive (Bacillus subtilis) bacteria compared to their pure counterparts. MTT assay reflects a sufficiently high percentage of cell viability and confirms the significant cytocompatibility of all the samples.

Exploring (bio)catalytic activities of structurally characterised Cu(ii) and Mn(iii) complexes: histidine recognition and photocatalytic application of Cu(ii) complex and derived CuO nano-cubes.

Structurally characterised two polymeric complexes of Cu(ii) (3) and Mn(iii) (4) of the ligand L (2-(((2-(phenylamino)ethyl)imino)methyl)phenol) have been explored for catecholase-like activity, fluorescence recognition of histidine and catalytic activity towards coupling of aryl iodides with benzamide, leading to N-arylbenzamides. CuO nano-cubes (NCs) prepared by thermal decomposition of the Cu(ii) complex function as photocatalysts for the degradation of methylene blue. Cube-like morphology of CuO nanocrystal and flake-shaped micrometer order Cu(ii) complex have been established from the field emissive scanning electron microscopy (FESEM) images.

Microstructure characterization of hydrothermally synthesized PANI/V2O5·nH2O heterojunction photocatalyst for visible light induced photodegradation of organic pollutants and non-absorbing colorless molecules.

Polyaniline intercalated vanadium oxide xerogel (PV) hybrid nanocomposite (NC) with novel structure has been successfully synthesized through a simple hydrothermal route. Detailed structure and microstructure characterization of PV NC is illustrated through Rietveld refinement of XRD data and FESEM/HRTEM images. Both FTIR and XPS spectra confirm the presence of PANI and water molecules within the NC and partial reduction of V5+ to V4+, corroborating with the results of XRD pattern analysis. Core-shell structure of PV NC, where PANI sheath layer acts as a shell covering around V2O5·nH2O crystalline core is confirmed from HRTEM images. Successive morphological changes of PV NC with different reaction time have been revealed from FESEM images. UV-vis spectra also confirm the formation of PV NC. Intercalation of water and PANI layers into V2O5·nH2O layer leads to a structural phase transition from orthorhombic to monoclinic phase due to substantial increase in interplanar spacing of (00l) of orthorhombic V2O5. The photocatalytic property of the as synthesized PV NC has been reported for the first time, with a promising photocatalytic activity for the degradation of organic dye, Rhodamine B (RhB) under visible light irradiation. It is attributed to a synergic effect in between PANI and V2O5·nH2O xerogel. The photocatalyst also shows remarkable real visible light photocatalytic activity with non-absorbing colorless test molecules like phenol and antibiotic kanamycin.

Facile synthesis of SnO2-PbS nanocomposites with controlled structure for applications in photocatalysis.

Recent studies have shown that SnO2-based nanocomposites offer excellent electrical, optical, and electrochemical properties. In this article, we present the facile and cost-effective fabrication, characterization and testing of a new SnO2-PbS nanocomposite photocatalyst designed to overcome low photocatalytic efficiency brought about by electron-hole recombination and narrow photoresponse range. The structure is fully elucidated by X-ray diffraction (XRD)/Reitveld refinement, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analysis, and transmission electron microscopy (TEM). Energy-dispersive X-ray spectroscopy (EDX) spectrum imaging analysis demonstrates the intermixing of SnO2 and PbS to form nanocomposites. A charge separation mechanism is presented that explains how the two semiconductors in junction function synergistically. The efficacy of this new nanocomposite material in the photocatalytic degradation of the toxic dye Rhodamine B under simulated solar irradiation is demonstrated. An apparent quantum yield of 0.217 mol min(-1) W(-1) is calculated with data revealing good catalyst recyclability and that charge separation in SnO2-PbS leads to significantly enhanced photocatalytic activity in comparison to either SnO2 or PbS.

Photoswitching and Thermoresponsive Properties of Conjugated Multi-chromophore Nanostructured Materials.

Conjugated multi-chromophore organic nanostructured materials have recently emerged as a new class of functional materials for developing efficient light-harvesting, photosensitization, photocatalysis, and sensor devices because of their unique photophysical and photochemical properties. Here, we demonstrate the formation of various nanostructures (fibers and flakes) related to the molecular arrangement (H-aggregation) of quaterthiophene (QTH) molecules and their influence on the photophysical properties. XRD studies confirm that the fiber structure consists of >95% crystalline material, whereas the flake structure is almost completely amorphous and the microstrain in flake-shaped QTH is significantly higher than that of QTH in solution. The influence of the aggregation of the QTH molecules on their photoswitching and thermoresponsive photoluminescence properties is revealed. Time-resolved anisotropic studies further unveil the relaxation dynamics and restricted chromophore properties of the self-assembled nano/microstructured morphologies. Further investigations should pave the way for the future development of organic electronics, photovoltaics, and light-harvesting systems based on π-conjugated multi-chromophore organic nanostructured materials.

Quickest single-step mechanosynthesis of CdS quantum dots and their microstructure characterization.

CdS quantum dots (QDs) with a mixture of both cubic (Zinc-blende) and hexagonal (Wurtzite) phases have been prepared within 50 min by mechanical alloying the stoichiometric mixture of Cd and S powders at room temperature in a planetary ball mill under Ar. The Rietveld analysis of X-ray powder diffraction data collected from ball-milled samples estimates relative phase abundances of cubic and hexagonal phases and several microstructure parameters like lattice parameters, particle size, lattice strain, concentrations of different kinds of stacking faults etc. in both kinds of QDs. Initially, the hexagonal phase is formed and then simultaneously, the most dense plane (111) of minor cubic phase is formed coherently on the most dense (002) plane of hexagonal phase. In the course of milling up to 30 h, the hexagonal phase partially transforms slowly to cubic phase and the molar ratio of cubic and hexagonal phase becomes approximately 0.7:0.3 and particles sizes of both phases reduce to approximately 6 nm. The cubic phase contains a significant amount of lattice strain but the hexagonal phase is almost strain-free. The presence of different kinds of stacking faults is revealed clearly from the high resolution transmission electron microscope (HRTEM) images. The particle sizes of QDs and their distributions obtained from the Rietveld analysis agree well with the analysis of HRTEM images.