103 research outputs found

    Core–Shell Lanthanide Upconversion Nanophosphors as Four-Modal Probes for Tumor Angiogenesis Imaging

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    Multimodality imaging overcomes the shortage and incorporates the advantages of different imaging tools. Lanthanide-based nanoprobes are unique and have rich optical, magnetic, radioactive, and X-ray attenuation properties; however, simple doping of different lanthanide cations into one host can result in a material with multifunction but not the optimized properties. In this study, using NaLuF<sub>4</sub>:Yb,Tm as the core and 4 nm of <sup>153</sup>Sm<sup>3+</sup>-doped NaGdF<sub>4</sub> (half-life of <sup>153</sup>Sm = 46.3 h) as the shell, we developed a lanthanide-based core–shell nanocomposite as an optimized multimodal imaging probe with enhanced imaging ability. The lifetime of upconversion luminescence (UCL) at 800 nm and relaxation rate (1/<i>T</i><sub>1</sub>) were at 1044 μs and 18.15 s<sup>–1</sup>·mM<sup>–1</sup>, respectively; however, no significant decrease in the attenuation coefficient was observed, which preserved the excellent X-ray imaging ability. The nanomaterial NaLuF<sub>4</sub>:Yb,Tm@NaGdF<sub>4</sub>(<sup>153</sup>Sm) was confirmed to be effective and applicable for UCL imaging, X-ray computed tomography (CT), magnetic resonance imaging, and single-photon emission computed tomography (SPECT) <i>in vivo</i>. Furthermore, the NaLuF<sub>4</sub>:Yb,Tm@NaGdF<sub>4</sub>(<sup>153</sup>Sm) nanoparticles were applied in tumor angiogenesis analysis by combining multimodality imaging of CT, SPECT, and confocal UCL imaging, which shows its value of multifunctional nanoparticles NaLuF<sub>4</sub>:Yb,Tm@NaGdF<sub>4</sub>(<sup>153</sup>Sm) in tumor angiogenesis imaging

    High-Efficiency Upconversion Luminescent Sensing and Bioimaging of Hg(II) by Chromophoric Ruthenium Complex-Assembled Nanophosphors

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    A chromophoric ruthenium complex-assembled nanophosphor (N719-UCNPs) was achieved as a highly selective water-soluble probe for upconversion luminescence sensing and bioimaging of intracellular mercury ions. The prepared nanophosphors were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDXA), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Further application of N719-UCNPs in sensing Hg2+ was confirmed by optical titration experiment and upconversion luminescence live cell imaging. Using the ratiometric upconversion luminescence as a detection signal, the detection limit of Hg2+ for this nanoprobe in water was down to 1.95 ppb, lower than the maximum level (2 ppb) of Hg2+ in drinking water set by the United States EPA. Importantly, the nanoprobe N719-UCNPs has been shown to be capable of monitoring changes in the distribution of Hg2+ in living cells by upconversion luminescence bioimaging

    Red-Light-Controllable Liquid-Crystal Soft Actuators via Low-Power Excited Upconversion Based on Triplet–Triplet Annihilation

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    A red-light-controllable soft actuator has been achieved, driven by low-power excited triplet–triplet annihilation-based upconversion luminescence (TTA-UCL). First, a red-to-blue TTA-based upconversion system with a high absolute quantum yield of 9.3 ± 0.5% was prepared by utilizing platinum­(II) tetra­phenyl­tetra­benzo­porphyrin (PtTPBP) as the sensitizer and 9,10-bis­(di­phenyl­phosphoryl)­anthracene (BDPPA) as the annihilator. In order to be employed as a highly effective phototrigger of photodeformable cross-linked liquid-crystal polymers (CLCPs), the PtTPBP&BDPPA system was incorporated into a rubbery polyurethane film and then assembled with an azotolane-containing CLCP film. The generating assembly film bent toward the light source when irradiated with a 635 nm laser at low power density of 200 mW cm<sup>–2</sup> because the TTA-UCL was effectively utilized by the azotolane moieties in the CLCP film, inducing their <i>trans</i>–<i>cis</i> photo­isomerization and an alignment change of the mesogens via an emission–reabsorption process. It is the first example of a soft actuator in which the TTA-UCL is trapped and utilized to create photomechanical effect. Such advantages of using this novel red-light-controllable soft actuator in potential biological applications have also been demonstrated as negligible thermal effect and its excellent penetration ability into tissues. This work not only provides a novel photo­manipulated soft actuation material system based on the TTA-UCL technology but also introduces a new technological application of the TTA-based upconversion system in photonic devices

    Blue-Emissive Upconversion Nanoparticles for Low-Power-Excited Bioimaging in Vivo

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    Water-soluble upconversion luminescent (UCL) nanoparticles based on triplet–triplet annihilation (TTA) were successfully prepared by coloading sensitizer (octaethylporphyrin Pd complex) and annihilator (9,10-diphenylanthracene) into silica nanoparticles. The upconversion luminescence quantum yield of the nanoparticles can be as high as 4.5% in aqueous solution. As determined by continuous kinetic scan, the nanoparticles have excellent photostability. Such TTA-based upconversion nanoparticles show low cytotoxicity and were successfully used to label living cells with very high signal-to-noise ratio. UCL imaging with the nanoparticles as probe is capable of completely eliminating background fluorescence from either endogenous fluorophores of biological sample or the colabeled fluorescent probe. In particular, such blue-emissive upconversion nanoparticles were successfully applied in lymph node imaging in vivo of living mouse with excellent signal-to-noise ratio (>25), upon low-power density excitation of continuous-wave 532 laser (8.5 mW cm–2). Such high-contrast and low-power excited bioimaging in vivo with a blue-emissive upconversion nanoparticle as probe may extend the arsenal of currently available luminescent bioimaging in vitro and in vivo

    High-Efficiency Upconversion Luminescent Sensing and Bioimaging of Hg(II) by Chromophoric Ruthenium Complex-Assembled Nanophosphors

    No full text
    A chromophoric ruthenium complex-assembled nanophosphor (N719-UCNPs) was achieved as a highly selective water-soluble probe for upconversion luminescence sensing and bioimaging of intracellular mercury ions. The prepared nanophosphors were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDXA), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Further application of N719-UCNPs in sensing Hg2+ was confirmed by optical titration experiment and upconversion luminescence live cell imaging. Using the ratiometric upconversion luminescence as a detection signal, the detection limit of Hg2+ for this nanoprobe in water was down to 1.95 ppb, lower than the maximum level (2 ppb) of Hg2+ in drinking water set by the United States EPA. Importantly, the nanoprobe N719-UCNPs has been shown to be capable of monitoring changes in the distribution of Hg2+ in living cells by upconversion luminescence bioimaging

    Quantum Yield Measurements of Photochemical Reaction-Based Afterglow Luminescence Materials

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    Afterglow materials have become one of the most promising luminescent materials due to their long luminescence lifetime. Photoluminescence quantum yield (PLQY), as one of the most fundamental and essential parameters of luminescent materials, can directly evaluate the luminescence properties of emissive compounds. Recently, a type of afterglow material based on a photochemical reaction has been developed. However, there is no suitable method to measure the PLQY of these afterglow materials due to their special luminescence principle. Herein, we present a method to measure the PLQY for these afterglow materials by collecting the luminescent dynamic curves of emission and excitation light at specific wavelength regions using a commercial spectrometer and an integrating sphere. We found that the emitted photons of this kind of afterglow material are in direct proportion to the excitation time, which means the PLQY is irrelevant to the excitation time

    3D Long-Range Triplet Migration in a Water-Stable Metal–Organic Framework for Upconversion-Based Ultralow-Power <i>in Vivo</i> Imaging

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    Triplet–triplet annihilation upconversion (TTA-UC) has gained increasing attention because it allows for harvesting of low-energy photons in the solar spectrum with high efficiency in relevant applications including solar cells and bioimaging. However, the utilization of conventional TTA-UC systems for low-power bioapplications is significantly hampered by their general incompatibility and low efficiency in aqueous media. Herein we report a metal–organic framework (MOF) as a biocompatible nanoplatform for TTA-UC to realize low-power <i>in vivo</i> imaging. Our MOF consists of a porphyrinic sensitizer in an anthracene-based Zr-MOF as a TTA-UC platform. In particular, closely aligned chromophores in the MOF facilitate a long-range 3D triplet diffusion of 1.6 μm allowing efficient energy migration in water. The tunable ratio between sensitizer and annihilator by our synthetic method also allows an optimization of the system for maximized TTA-UC efficiency in water at a very low excitation power density. Consequently, the low-power imaging of lymph node in a live mouse was successfully demonstrated with an excellent signal-to-noise ratio (SNR > 30 at 5 mW cm<sup>–2</sup>)

    Hemicyanine Dye as a Surfactant for the Synthesis of Bicontinuous Cubic Mesostructured Silica

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    In this paper, we developed a facile way to synthesize highly ordered optically active MCM-48 at room temperature, by using mixtures of hemicyanine dye N-alkyl-2-[p-(N,N-diethylamino)-o-(alkyloxy)]pyridinium bromide (denoted as o-CnPOCm, Scheme ) and cetyltrimethylammonium bromide (CTAB) as the structure-directing agents. The mesoporous materials were systematically characterized by powder X-ray diffraction, transmission electron microscopy, nitrogen sorption, and thermogravimetry. The resultant MCM-48 exibits unusually high thermal stability. For example, in the case of o-C2POC14, it can retain its cubic structure even under calcinations at 900 °C for 5 h, although the pore size is shifted to the micropore region because of shrinkage of the framework. The typical surface area and pore volume are 980 m2/g and 0.44 cm3/g, respectively, for the powder calcined under such a high temperature. This is the first report of room-temperature synthesis of MCM-48 with such good thermal stability using cationic−cationic mixed surfactant as the structure-directing agent. The fluorescence lifetimes of the as-synthesized mesostructured MCM-48 were also measured, and the result showed that the incorporated dye molecules have a 1 order of magnitude longer lifetime than that of free species in solution, showing that the hemicyanine dye molecules are well dispersed within the CTAB surfactant matrix. Furthermore, we compared eight other dye congeners (Scheme ) to fully investigate the mesophase resulting from the dye−CTAB system. The results show that, upon addition of the dye surfactant to the starting mixtures, the mesostructured silica undergoes an intrinsic phase-transition process; however, specific dye geometry is required to obtain MCM-48 at room temperature. Those functionalities as well as the designed synthesis of this novel mesostructured MCM-48 material promise a bright future in multifunctional optical and electric nano- and microdevices (e.g., waveguides, laser, light-emitting diodes, etc.) and also shed light on the self-assembly behavior in complex colloidal system

    Afterglow/Fluorescence Dual-Emissive Ratiometric Oxygen Probe for Tumor Hypoxia Imaging

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    Hypoxia is a common feature of many diseases such as solid tumors. The measurement and imaging of oxygen (O2) are extremely important for disease diagnosis and therapy evaluation. In this work, the afterglow/fluorescence dual-emissive ratiometric O2 probe based on a photochemical reaction-based afterglow system is reported. The afterglow is highly sensitive to O2 because the O2 content is directly related to the 1O2 yield and eventually affects the afterglow intensity. The O2-insensitive fluorescence of an emitter can serve as an internal reference. As the O2 concentration changes from 0.08 to 18.5 mg L–1, the ratio value shows a remarkable 53-fold increase. Compared with the intensity of a single peak, the ratiometric signal can eliminate the interference of the probe concentration to achieve higher accuracy. This afterglow/fluorescence dual-emissive ratiometric O2 probe is successfully applied to hypoxia imaging in tumor-bearing mice, which may further promote the development of O2 sensing in the biomedical field
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