Synthesizing Ag+: MgS, Ag+: Nb2S5, Sm3+: Y2S3, Sm3+:Er2S3, and Sm3+:ZrS2 Compound Nanoparticles for Multicolor Fluorescence Imaging of Biotissues.
ABSTRACT: Development of the fluorophores whose fluorescence bands can be flexibly selected is of great interest for biotissue imaging. Compounds of Ag+:MgS, Ag+:Nb2S5, Sm3+:Y2S3, Sm3+:Er2S3, and Sm3+:ZrS2 were obtained through new chemical synthesis. They were characterized by X-ray photoelectron spectroscopy, X-ray diffraction spectroscopy, and transmission electron microscopy. They revealed polychromatic-photoluminescence spectra when excited by 280, 380, 480, 580, 680, and 785 nm light. Especially, near-infrared emission ranging from 800-1100 nm was found upon 785 nm light excitation. A band model was proposed to explain transitions responsible for the observed components of emission. Their broad fluorescence spectra cover from the ultraviolet to near-infrared spectral range. Their ability of emitting wide-range fluorescence was utilized for multicolor fluorescence imaging of biotissues, as demonstrated by pig-kidney tissue samples.
Project description:Below the Earth's crust, temperatures may reach beyond 600?K, impeding the batteries used to power conventional thermometers. Fluorescence intensity ratio based temperature probes can be used with optical fibers that can withstand these conditions. However, the probes tend to exhibit narrow operating ranges and poor sensitivity above 400?K. In this study, we have investigated single and dual layered YVO<sub>4</sub>: Ln<sup>3+</sup> (Ln?=?Nd, Sm, Eu, Dy, Ho, Er, Tm, Yb) thin films (100-150?nm) for use in fluorescence intensity ratio based temperature sensors in the 300-850?K range. The type of lanthanide emission can be fine-tuned by adjusting the thickness of each layer, and the layered structure allows for emission from otherwise incompatible lanthanide pairs. This novel multi-layered approach enables high sensitivity over a broad temperature range. The highest relative sensitivity was achieved for a dual layered YVO<sub>4</sub>: Eu<sup>3+</sup>/YVO<sub>4</sub>: Dy<sup>3+</sup> sample, exhibiting a maximum sensitivity of 3.6% K<sup>-1</sup> at 640?K. The films were successfully deposited on all tested substrates (silicon, iron, aluminum, glass, quartz, and steel), and can be applied homogenously to most surfaces without the use of binders. The films are unaffected by water, enabling non-contact temperature sensing in water, where IR thermometers are not an option.
Project description:What ideal w-LED phosphors always aim to do is to achieve a single phase near-sunlight emission phosphor simultaneously with both high luminescence efficiency and high thermal stability at operation temperature. And It is well known that apatite compound phosphors are one of the most promising optical materials to realize those above because of their unique structure enhanced luminescence properties and thermal stability. Here, we synthesized a co-doped single phase apatite phosphors Ca<sub>2</sub>La<sub>8</sub>(SiO<sub>4</sub>)<sub>6</sub>O<sub>2</sub>:Dy<sup>3+</sup>/Sm<sup>3+</sup> (CLSO:Dy<sup>3+</sup>/Sm<sup>3+</sup>) for white light emission, which was provided with excellent thermal stability and of which luminescence intensity at 150 °C still was 92 percentage of that at room temperature. Moreover, X-ray diffraction technique, Fourier transform infrared spectroscopy, scanning electron microscope were employed to characterization of phase structure and morphology, and consequently pure apatite structure and gravel-like morphology of phosphors were proved. Analysis of photoluminescence spectra indicated that concentration quenching effect exist in single-doped CLSO:Dy<sup>3+</sup> phosphors owing to dipole-dipole interaction between Dy<sup>3+</sup> ions. It is revealed that maybe exist Dy<sup>3+</sup>???Sm<sup>3+</sup> bilateral non-radiative energy transfer processes in Dy<sup>3+</sup>/Sm<sup>3+</sup> co-doped CLSO system by PL spectra and decay curves. And variation of Sm<sup>3+</sup> ion concentration can control color emission, namely CIE chromaticity coordinates and correlated color temperature, finally to achieve white light emission (0.309,0.309) with CCT 6848?K, able to be a potential candidate for commercial lighting applications.
Project description:In this study, silver (Ag) island modified up-conversion nano-particle (NaGdF<sub>4</sub>:Yb<sup>3+</sup>/Tm<sup>3+</sup>) thin films were prepared <i>via</i> electrostatic layer by layer (LBL) and spin coating techniques. The spectroscopic results indicated that adding Ag nanoparticles could significantly enhance the up-conversion emission of NaGdF<sub>4</sub>:Yb<sup>3+</sup>/Tm<sup>3+</sup> thin films at 452 nm and 476 nm. The maximum enhancement factor of ∼15.6 was reached at 476 nm. Furthermore, we prepared microfibers from upconverting nanoparticles solution, the application of microfibers as active and passive waveguides was analyzed by observing the performance of microfibers with and without Ag under 980 nm excitation of the laser source. The fluorescence intensity ratio (FIR) method was adopted to evaluate microfiber sensitivity. The intensity-based temperature sensitivity of blue emission from a single microfiber containing up-conversion nanomaterials (NaGdF<sub>4</sub>:Yb<sup>3+</sup>/Tm<sup>3+</sup>) and Ag nanoparticles reached up to 0.018 K<sup>-1</sup> at 310 K compared to 0.0029 K<sup>-1</sup> in Ag-free microfiber. Our results suggest that the novel material can be used to construct new nano-thermometers, useful both in biological experiments as well as industrial research.
Project description:Near-infrared (NIR) photostimulated luminescence (PSL) nanocrystals (NCs) have recently evoked considerable interest in the field of biomedicine, but are currently limited by the controlled synthesis of efficient PSL NCs. Herein, we report for the first time the controlled synthesis of CaS:Eu<sup>2+</sup>,Sm<sup>3+</sup> NIR PSL NCs through a high-temperature co-precipitation method. The role of Sm<sup>3+</sup> co-doping and the effect of thermal annealing on the optical properties of the NCs as well as the charging and discharging processes, the trap depth distribution, and the underlying PSL mechanism are comprehensively surveyed by means of photoluminescence, persistent luminescence, thermoluminescence, and PSL spectroscopies. The as-prepared NCs exhibit intense PSL of Eu<sup>2+</sup> at 650 nm with a fast response to stimulation in a broad NIR region from 800 nm to 1600 nm, a duration time longer than 2 h, and an extremely low power density threshold down to 10 mW cm<sup>-2</sup> at 980 nm. Furthermore, by taking advantage of the intense NIR PSL, we demonstrate the application of CaS:Eu<sup>2+</sup>,Sm<sup>3+</sup> NCs as sensitive luminescent nanoprobes for biotin receptor-targeted cancer cell imaging. These results reveal the great promise of CaS:Eu<sup>2+</sup>,Sm<sup>3+</sup> nanoprobes for autofluorescence-free bioimaging, and also lay the foundation for future design of efficient NIR PSL nanoprobes towards versatile bioapplications.
Project description:The development of nanomaterials with special optical window is critical for clinical applications and the optoelectronic industry. In this work, eight kinds of samarium-based metal organic compound nanoparticles (Sm-Fe, Sm-Ga, Sm-Mn, Sm-Na, Sm-Nb, Sm-W, Sm-Cu, and Sm-Al) were synthesized through a solution method. They show polychromatic-photoluminescence spectra extended from the UV to near-infrared (NIR) region when excited by 280 nm, 380 nm, 480 nm, 580 nm, and 785 nm light. They emit direct white light with respect to UV excitation. Tunable white-to-green fluorescence can be achieved by variation of excitation light around 300-400 nm. When they are excited by a 785 nm light source, they show intense fluorescence around 800-1100 nm, which is promising for NIR bio-imaging. Their application in multicolor ultra-wide-range bio-tissue fluorescence imaging is demonstrated by UV (359-371 nm), blue (450-490 nm), green (540-552 nm), and NIR light (central wavelength = 785 nm) excitation with pig kidney tissue samples.
Project description:Stable water-soluble copper sulfide(Cu<sub>2</sub>S) quantum dots(QDs) with near-infrared emission were synthesized using N-acetyl-L-cysteine(NAC) as a modifier in aqueous solution and nitrogen atmosphere at room temperature. The product was characterized by TEM, XRD, XPS, FT-IR, FL and UV-VIS spectrometers. Effects of preparation conditions such as pH values, the molar ratio of reactants, temperature, and metal ions on the fluorescence properties of Cu<sub>2</sub>S QDs were discussed. Under optimal conditions, the prepared Cu<sub>2</sub>S QDs with average diameter about 2-5?nm show a near-infrared emission at 770?nm with the excitation wavelength of 466?nm, and have a good detection sensitivity for ions of Hg<sup>2+</sup>, Ag<sup>+</sup> and Au<sup>3+</sup>, based on the characteristic of fluorescence quenching. The fluorescence quenching mechanism was proposed via electron transfer with cation exchange, which based on the theory of Hard-Soft-Acid-Base (HSAB) and Ksp value of metal-sulfide.
Project description:The isolation of [K(2.2.2-cryptand)][Ln(C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sub>3</sub>], formally containing Ln<sup>II</sup>, for all lanthanides (excluding <i>Pm</i>) was surprising given that +2 oxidation states are typically regarded as inaccessible for most 4f-elements. Herein, X-ray absorption near-edge spectroscopy (XANES), ground-state density functional theory (DFT), and transition dipole moment calculations are used to investigate the possibility that Ln(C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sub>3</sub><sup>1-</sup> (Ln = Pr, Nd, Sm, Gd, Tb, Dy, Y, Ho, Er, Tm, Yb and Lu) compounds represented molecular Ln<sup>II</sup> complexes. Results from the ground-state DFT calculations were supported by additional calculations that utilized complete-active-space multi-configuration approach with second-order perturbation theoretical correction (CASPT2). Through comparisons with standards, Ln(C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sub>3</sub><sup>1-</sup> (Ln = Sm, Tm, Yb, Lu, Y) are determined to contain 4f<sup>6</sup> 5d<sup>0</sup> (Sm<sup>II</sup>), 4f<sup>13</sup> 5d<sup>0</sup> (Tm<sup>II</sup>), 4f<sup>14</sup> 5d<sup>0</sup> (Yb<sup>II</sup>), 4f<sup>14</sup> 5d<sup>1</sup> (Lu<sup>II</sup>), and 4d<sup>1</sup> (Y<sup>II</sup>) electronic configurations. Additionally, our results suggest that Ln(C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>)<sub>3</sub><sup>1-</sup> (Ln = Pr, Nd, Gd, Tb, Dy, Ho, and Er) also contain Ln<sup>II</sup> ions, but with 4f <sup><i>n</i></sup> 5d<sup>1</sup> configurations (not 4f <sup><i>n</i>+1</sup> 5d<sup>0</sup>). In these 4f <sup><i>n</i></sup> 5d<sup>1</sup> complexes, the <i>C</i><sub>3h</sub>-symmetric ligand environment provides a highly shielded 5d-orbital of <i>a</i>' symmetry that made the 4f <sup><i>n</i></sup> 5d<sup>1</sup> electronic configurations lower in energy than the more typical 4f <sup><i>n</i>+1</sup> 5d<sup>0</sup> configuration.
Project description:Reliable, label-free, and ultraselective detection of Pb<sup>2+</sup> and Ag<sup>+</sup> ions is of paramount importance for toxicology assessment, human health, and environmental protection. Herein, we present a novel recyclable fluorometric aptasensor based on the Pb<sup>2+</sup> and Ag<sup>+</sup>-induced structural change of the GC-rich ssDNA (guanine cytosine-rich single-strand DNA) and the differences in the fluorescence emission of acridine orange (AO) from random coil to highly stable G-quadruplex for the detection of Pb<sup>2+</sup> and Ag<sup>+</sup> ions. More interestingly, the construction and principle of the aptasensor explore that the GC-rich ssDNA and AO can be strongly adsorbed on the CaSnO<sub>3</sub>@PDANS surface through the π-π stacking, hydrogen-bonding, and metal coordination interactions, which exhibit high fluorescence quenching and robust holding of the GC-rich ssDNA. However, in the presence of Pb<sup>2+</sup>, the specific G-rich ssDNA segment could form a stable G-quadruplex via G4-Pb<sup>2+</sup> coordination and capture of AO from the CaSnO<sub>3</sub>@PDANS surface resulting in fluorescence recovery (70% enhancement). The subsequent addition of Ag<sup>+</sup> ion induces coupled cytosine base pairs in another segment of ssDNA to get folded into a duplex structure together with the G-quadruplex, which highly stabilizes the G-quadruplex resulting in the maximum recovery of AO emission (99% enhancement). When the Cys@Fe<sub>3</sub>O<sub>4</sub>Nps are added to the above solution, the sensing probe was restored by complexation between the Cys in the Cys@Fe<sub>3</sub>O<sub>4</sub>Nps and target metal ions, resulting in the fabrication of a highly sensitive recyclable Pb<sup>2+</sup> and Ag<sup>+</sup> assay with detection limits of 0.4 and 0.1 nM, respectively. Remarkably, the Cys@Fe<sub>3</sub>O<sub>4</sub>Nps can also be reused after washing with EDTA. The utility of the proposed approach has great potential for detecting the Pb<sup>2+</sup> and Ag<sup>+</sup> ions in environmental samples with interfering contaminants.
Project description:The ratio of the intensity of Tb<sup>3+</sup> fluorescence at 543 nm because of an electric dipole transition (<sup>5</sup>D<sub>4</sub>-<sup>7</sup>F<sub>5</sub>) relative to that at 437 nm due to a magnetic dipole transition (<sup>5</sup>D<sub>3</sub>-<sup>7</sup>F<sub>4</sub>) was determined to be proportional to the amount of metastable CaAl<sub>2</sub>Si<sub>2</sub>O<sub>8</sub> crystals precipitated in CaO-Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> glass. The present results indicate that Tb<sup>3+</sup> luminescence can be used as a probe to evaluate the crystallization of glass.
Project description:In this study, electrochemical properties of layered perovskites having non-stoichiometric compositions (Sm<sub>1-x</sub>BaCo<sub>2</sub>O<sub>5+d</sub>, <i>x</i> = 0, 0. 01, 0.02, 0.03, 0.04, 0.05, 0.10, and 0.15) were analyzed for the direct application of cathode materials for Intermediate Temperature-operating Solid Oxide Fuel Cells (IT-SOFC). From the Sm<sub>1-x</sub>BaCo<sub>2</sub>O<sub>5+d</sub> oxide systems calcined at 1,100°C for 8 h, single phase (SmBaCo<sub>2</sub>O<sub>5+d</sub>, SBCO_1) was maintained only in the case of the <i>x</i> = 0 composition. In the compositions of <i>x</i> = 0.05-0.10, BaCoO<sub>2.6</sub> was mixed with the pattern of SBCO. In addition, in the composition of <i>x</i> = 0.15, it was confirmed that BaCoO<sub>2.6</sub> and CoO phases coexisted with SBCO. In the compositions of Sm<sub>1-x</sub>BaCo<sub>2</sub>O<sub>5+d</sub>, the overall Area Specific Resistance (ASR) values decreased as the removal amount of Sm increased from <i>x</i> = 0-0.10; then, the values increased for compositions from <i>x</i> = 0.15. For example, the ASRs of SBCO_1, Sm<sub>0.95</sub>BaCo<sub>2</sub>O<sub>5+d</sub> (SBCO_0.95), Sm<sub>0.90</sub>BaCo<sub>2</sub>O<sub>5+d</sub> (SBCO_0.90), and Sm<sub>0.85</sub>BaCo<sub>2</sub>O<sub>5+d</sub> (SBCO_0.85) measured at 600°C were 0.301, 0.147, 0.119, and 0.179 Ω cm<sup>2</sup>, respectively. In particular, SBCO_0.90 was found to have an excellent ASR property of about 0.035 Ω cm<sup>2</sup> at 700°C. Typical properties of the metal-insulator transition (MIT) electrical conductivity were shown in all measured compositions. The temperature at which MIT occurred increased as the non-stoichiometric composition increased.