A dual-channel chemodosimetric sensor for discrimination between hypochlorite and nerve-agent mimic DCP: application on human breast cancer cells.

A styryl bridge containing a triphenylamine-thioimidazole hydrazine-based dual-analyte-responsive fluorescent sensor was designed and synthesized for the detection of the nerve gas simulant diethyl chlorophosphate (DCP) and hypochlorite (OCl-) for the first time. Hypochlorite induces oxidative intramolecular cyclization to give a triazole structure, which exhibited blue fluorescence with excellent selectivity and a low detection limit (8.05 × 10-7 M) in solution. Conversely, the probe forms a phosphorylated intermediate with diethyl chlorophosphate, which undergoes further hydrolyzation and presents green fluorescence in a ratiometric mode with a low detection limit (3.56 × 10-8 M). Additionally, the as-designed sensor was utilized to construct a portable kit for real-time monitoring of DCP in a discriminatory, simple and safe manner. Lastly, the probe was also productively employed for in situ imaging of OCl- and DCP in the living cell.

Visible light photocatalysts from low-grade iron ore: the environmentally benign production of magnetite/carbon (Fe3O4/C) nanocomposites.

Magnetite (Fe3O4) nanoparticles coated with dextrose and gluconic acid possessing both super-paramagnetism and excellent optical properties have been productively synthesized through a straightforward, efficient and cost-efficient hydrothermal reduction route using Fe3+ as sole metal precursor acquired from accumulated iron ore tailings-a mining waste that usually represents a major environmental threat. Fe3O4/C nanocomposites were fully elucidated by FEGSEM and TEM, revealing a combination of platelets (<1 µm) capped by particles (<10 nm) and magnetite which was verified by XPS, which demonstrated also oxygen deficiency. A dextrose/gluconic acid coating was elucidated by Fourier transform-infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The Fe3O4/C nanocomposites were found to be superparamagnetic at room temperature. Meanwhile, their optical properties were investigated by UV-visible diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence (PL) spectroscopy; an Eg of 1.86 eV was determined, and emissions at 612 and 650 nm (ex. 250 nm) were consistent with the XPS identification of oxygen vacancies. The efficacy of the as-synthesized magnetically recoverable magnetite/carbon (Fe3O4/C) nanocomposites has been exhibited in the photocatalytic degradation of the toxic textile (industrial) dye bodactive red BNC-BS.

A ratiometric triazine-based colorimetric and fluorometric sensor for the recognition of Zn2+ ions and its application in human lung cancer cells.

Herein, we introduce new ratiometric 2,4,6-triamino-1,3,5-triazine-based probes (R1 and R2) having three different binding sites for three metal ion binders, which can selectively detect Zn2+ ions and, particularly, the probe R1 strongly interacts with the human lung cancer cell line (A549). Both the probes R1 and R2 are competently selective towards the Zn2+ ions with the detection limits of 1.22 × 10-7 M and 1.13 × 10-7 M, respectively. The changes in the structure and absorption properties of the probes are explained by density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. The absorption and fluorescence color change in the solid TLC plate makes it a brilliant Zn2+ sensor in a portable form.

A one-pot fluorogenic cascade cyclization reaction via BF3-sensing.

(E)-3-Phenyl-1-(2-(phenylethynyl) phenyl) prop-2-en-1-one is shown as a chemodosimetric sensor where it selectively senses toxic BF3, scrutinized through electronic spectral analysis and recognized with the naked eye. The probable binding mechanism is proposed based on the electronic spectral analysis, NMR titration and the ESI-MS technique. The incredible increase in fluorescence intensity (60-fold) in less than 2 minutes along with an extremely low detection limit (6.36 × 10-10 M) in a range of 0-50 µl make it function as a proficient gas phase BF3 sensor with synchronized detection in a portable form.

Recent Advances on the Optical Properties of Eu3+ Ion in Nano-Systems.

Rare-earth (RE) doped nanomaterials have already proven promising materials for advanced materials and technologies including optics, lasers, catalysts, alloys, magnets, electronics, lighting, bioanalyses, imaging etc. because of their outstanding properties such as extremely narrow emission bands, long lifetimes, large strokes shifts, photostability and absence of blinking. The efficient of RE doped phosphors is found to be controlled by tuning nonradiative relaxation pathway which eventually controls by tuning crystal phase of host, lattice vibration, concentration of dopant etc. Cross relaxation nonradiative decay due to concentration quenching can be manipulated by controlling dopant concentration. This review article highlights the optical properties of Eu3+ ion in various hosts such as fluoride, phosphate, silica, semiconductor, oxyhalide, vanadate, molybdate and tungstate because of its importance for potential applications. It is important to know how the host environment influences the radiative and nonradiative relaxation which eventually controls the overall photoluminescence properties. Of particular attention is how the optical properties of Eu3+ ion vary with changing the host environment with the anticipation that such knowledge will permit us to construct efficient nanomaterials. Finally, a tentative outlook on future advances of this research field is given.

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.

Influence of size and shape on the photocatalytic properties of SnO2 nanocrystals.

Tuning the functional properties of nanocrystals is an important issue in nanoscience. Here, we are able to tune the photocatalytic properties of SnO2 nanocrystals by controlling their size and shape. A structural analysis was carried out by using X-ray diffraction (XRD)/Rietveld and transmission electron microscopy (TEM). The results reveal that the number of oxygen-related defects varies upon changing the size and shape of the nanocrystals, which eventually influences their photocatalytic properties. Time-resolved spectroscopic studies of the carrier relaxation dynamics of the SnO2 nanocrystals further confirm that the electron-hole recombination process is controlled by oxygen/defect states, which can be tuned by changing the shape and size of the materials. The degradation of dyes (90%) in the presence of SnO2 nanoparticles under UV light is comparable to that (88%) in the presence of standard TiO2 Degussa P-25 (P25) powders. The photocatalytic activity of the nanoparticles is significantly higher than those of nanorods and nanospheres because the effective charge separation in the SnO2 nanoparticles is controlled by defect states leading to enhanced photocatalytic properties. The size- and shape-dependent photocatalytic properties of SnO2 nanocrystals make these materials interesting candidates for photocatalytic applications.

Lanthanide-doped nanocrystals: strategies for improving the efficiency of upconversion emission and their physical understanding.

The fundamental understanding of lanthanide-doped upconverted nanocrystals remains a frontier area of research because of potential applications in photonics and biophotonics. Recent studies have revealed that upconversion luminescence dynamics depend on host crystal structure, size of the nanocrystals, dopant concentration, and core-shell structures, which influence site symmetry and the distribution and energy migration of the dopant ions. In this review, we bring to light the influences of doping/co-doping concentration, crystal phase, crystal size of the host, and core-shell structure on the efficiency of upconversion emission. Furthermore, the lattice strain, due to a change in the crystal phase and by the core-shell structure, strongly influences the upconversion emission intensity. Analysis suggests that the local environment of the ion plays the most significant role in modification of radiative and nonradiative relaxation mechanisms of overall upconversion emission properties. Finally, an outlook on the prospects of this research field is given.

Impacts of core-shell structures on properties of lanthanide-based nanocrystals: crystal phase, lattice strain, downconversion, upconversion and energy transfer.

This feature article highlights the new development and current status of rare-earth (RE) based core-shell nanocrystals, which is one of the new classes of hybrid nanostructures. Attractive properties of rare-earth based nanomaterials include extremely narrow emission bands, long lifetimes, large Stoke's shifts, photostability and absence of blinking that can be exploited for biophotonic and photonic applications. Core-shell nanostructures have been attracting a great deal of interest to improve the luminescence efficiency by the elimination of deleterious cross-relaxation. The main focus of this feature article is to address the impacts of core-shell structures on the properties of lanthanide based nanocrystals including crystal phase, lattice strain, downconversion emission, upconversion emission and energy transfer. We describe general synthetic methodologies to design core-shell nanostructure materials. An interesting finding reported is that the local environment of an ion in the core-shell structure significantly affects the modifications of radiative and nonradiative relaxation mechanisms. Finally, a tentative outlook on future developments of this research field is given. Here, we attempt to identify the critical parameters governing the design of luminescent lanthanide based core-shell nanostructures.

Energy transfer study between Ce3+ and Tb3+ ions in doped and core-shell sodium yttrium fluoride nanocrystals.

Here, we report the preparation of Ce(3+) and Tb(3+) co-doped sodium yttrium fluoride nanorods and NaYF(4):Ce(3+)/Tb(3+) core-shell nanoparticles by the emulsion method. The core-shell nanoparticles are confirmed by X-ray diffraction study and transmission electron microscopy (TEM) analysis. The hexagonal crystal phase of Ce(3+)-doped sodium yttrium fluoride nanocrystals is converted to the cubic polymorph after surface coating by TbF(3). Cell volume, cell parameters and lattice strain have been modified due to core-shell structure. The decay times are found to be 8.4 ms and 5.4 ms for doped nanorods and core-shell nanoparticles, respectively, which reveals that non-radiative decay is higher in the case of core-shell nanoparticles than doped nanorods. Energy transfer efficiencies from Ce(3+) to Tb(3+)are 65% and 45% for doped Na(Y(1.5)Na (0.5))F(6):Ce:Tb material and NaYF(4):Ce/Tb core-shell materials, respectively. Quantum yields are found to be 75% and 42% for doped and core-shell samples, respectively.