Luminescence Agent Research Articles

Water-soluble photoluminescent d-mannose and l-alanine functionalized silicon nanocrystals and their application to cancer cell imaging.

Herein, we report the straightforward synthesis, photoluminescent properties, and cell imaging studies of d-mannose and l-alanine functionalized silicon nanocrystals (SiNCs). Tailoring nanocrystal surface functionalization is essential to interfacing SiNCs with their environment and rendering them stable - surface modification also offers the opportunity to target specific cell types for imaging. A simple and versatile surface modification procedure was developed to tether biomolecules onto the SiNC surfaces and render them water-soluble. The presented approach is precious metal-catalyst free, straightforward, and provides carbohydrate and amino acid functionalized SiNCs. The functionalized SiNCs have been investigated by fluorescence microscopy and our results indicate that they can be internalized by MCF-7 human breast cancer cells as shown in the cell imaging studies. The obtained SiNCs were characterized using FTIR, XPS, PL, and TEM.

Near-infrared photocatalysts of BiVO4/CaF2:Er3+, Tm3+, Yb3+with enhanced upconversion properties

Upconversion photocatalysts have the potential to absorb the near-infrared (NIR) light in solar energy and improve the photocatalytic performance. A hierarchical upconversion photocatalyst of BiVO₄ (BVO)/CaF₂:Er(3+), Tm(3+), Yb(3+) (CF) combined with the narrow-band semiconductor of BVO and the luminescence agent of CF to enhance upconversion properties was synthesized via the hydrothermal method. The CF particles were deposited homogeneously on the surface of the BVO/CF composite with regular dendritic structure, which led to efficient upconversion emissions. The upconversion emission intensity of the BVO/CF composite was 8 times higher than that of pure CF, through tailoring the crystal symmetry of lanthanide ions by Bi(3+) ions. The upconverted ultraviolet (361 and 379 nm), violet (408 nm), and blue (485 nm) light was able to excite BVO for photocatalysis in BVO/CF under NIR irradiation, which improved the degradation rate of methyl orange (MO).

The influence of Yb, B, and Ga-doped Er3+:Y3Al5O12 on solar light photocatalytic activity of TiO2 in degradation of organic dyes

Five up-conversion luminescence agents (Er3+:Y3Al5O12, Er3+:Yb n Y3 − n Al5O12, Er3+:Y3B a Al5 − a O12, Er3+:Y3Ga b Al5 − b O12, and Er3+:Yb n Y3 − n B a Ga b Al5 − a − b O12) were synthesized using sol-gel method and then the corresponding coated composites (Er3+:Y3Al5O12/TiO2, Er3+:Yb n Y3−n Al5O12/TiO2, Er3+:Y3B a Al5 − a O12/TiO2, Er3+:Y3Ga b Al5 − b O12/TiO2, and Er3+:Yb n Y3 − n B a Ga b Al5 − a − b O12/TiO2) as photocatalysts were prepared by sol-gel coating process. The XRD and SEM were used to confirm the crystalline phase and surface morphology. The UV-vis absorption and fluorescence-emission spectra were used to research the effect of doping category and amount on the up-conversion emission ability. The photocatalytic activities were detected through the degradation of Acid Red B dye in aqueous solution. Some key parameters of catalyst amount and initial concentration of organic dye on solar light photocatalytic degradation were also examined. The extensive feasibility of prepared photocatalysts in solar light degradation was detected by other organic dyes. The results suggest that the photocatalysts can be widely used in sewage treatment.

Visible-light photocatalytic activity of Pt supported TiO2 combined with up-conversion luminescence agent (Er3+:Y3Al5O12) for hydrogen production from aqueous methanol solution

In this paper, a high effective up-conversion luminescence agent (Er3+:Y3Al5O12) is synthesized by sol–gel method, and then its corresponding visible-light photocatalyst (Er3+:Y3Al5O12/Pt–TiO2) is successfully prepared by direct mixing and calcination methods. For comparison, Er3+:Y3Al5O12, Pt–TiO2 and Er3+:Y3Al5O12/Pt–TiO2 are all characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). At first, the up-conversion luminescence properties of Er3+:Y3Al5O12 are reviewed by excitation spectrum in visible-light region and emission spectrum in ultraviolet-light region. And then, under visible-light irradiation the visible-light photocatalytic activity of Er3+:Y3Al5O12/Pt–TiO2 is examined through photocatalytic hydrogen production from aqueous methanol solution. Lastly, the influence factors such as Er3+:Y3Al5O12 and Pt–TiO2 mole ratio, heat-treated temperature and heat-treated time on the visible-light photocatalytic hydrogen production activity of Er3+:Y3Al5O12/Pt–TiO2 are studied. Particularly, Er3+:Y3Al5O12/Pt–TiO2 with 6:100 M ratio heat-treated at 550 °C for 90 min shows the highest photocatalytic activity in hydrogen production from aqueous methanol solution.

Improvement of sonocatalytic activity of TiO2 by using Yb, N and F-doped Er3+:Y3Al5O12 for degradation of organic dyes

In this study, several up-conversion luminescence agents (Er3+:Y3Al5O12, Er3+:Yb0.2Y2.79Al5O12, Er3+:Yb0.2Y2.79Al5N0.01O11.99, Er3+:Yb0.2Y2.79Al5F0.01O11.99 and Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98) were synthesized using sol–gel method. And then, the corresponding sonocatalyst (Er3+:Y3Al5O12/TiO2, Er3+:Yb0.2Y2.79Al5O12/TiO2, Er3+:Yb0.2Y2.79Al5N0.01O11.99/TiO2, Er3+:Yb0.2Y2.79Al5F0.01O11.99/TiO2 and Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98/TiO2 coated composites) were prepared by sol–gel coating process. The synthesized up-conversion luminescence agents and their coated composites were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). And that, the sonocatalytic activities were detected through the degradation of Azo Fuchsine (AF) dye in aqueous solution by UV–vis spectroscopy. Some key influences such as heat-treated temperature and heat-treated time on the sonocatalytic activity of Er3+:YbaY2.99−aNxFyAl5O12−x−y/TiO2 coated composite, as well as ultrasonic irradiation time and initial dye concentration on the sonocatalytic degradation were studied. The results showed that the doping of Yb, N and F into Er3+:Y3Al5O12/TiO2 significantly enhanced the sonocatalytic activity of Er3+:Y3Al5O12/TiO2 coated composite in the degradation of organic dyes. Particularly, Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98/TiO2 coated composites with 3:7M ratio heat-treated at 550°C for 60min showed the highest sonocatalytic activity. At last, the experiments also indicated that the Er3+:Yb0.2Y2.79Al5N0.01F0.01O11.98/TiO2 coated composites has a good sonocatalytic activity to degrade other organic dyes under ultrasonic irradiation.

High-Relaxivity and Luminescent Silica Nanoparticles As Multimodal Agents for Molecular Imaging

The design and synthesis of a new bimodal contrast agent for magnetic resonance imaging and optical imaging is reported. Tunable-sized silica nanoparticles were synthesized by a microemulsion-mediated pathway and used as carriers for paramagnetic and luminescent probes. The near-infrared luminescent agent was a ruthenium complex that was directly entrapped in the silica shell to provide photoluminescence enhancement and to make it highly photostable as it was protected from the surrounding environment. The paramagnetic activity came from a Gd-DTPA derivative that was grafted on the silica surface. NMRD profiles showed a strong relaxivity enhancement (increase of 432% in the r1 value at 20 MHz) when the paramagnetic complex was grafted at the nanoparticle surface, because of a reduction of its mobility. Polyethylene glycol was also grafted at the nanoparticle surface to enhance the nanoparticle residence time in the bloodstream. A thorough characterization of the material confirmed its potential as a very effective bimodal contrast agent.

Luminescence phenomena of biodegradable photoluminescent poly(diol citrates)

The possible origin of luminescent properties of biodegradable photoluminescent polyesters (BPLPs) has been revealed by isolation and identification of luminescent agent from the hydrolyzate of BPLP. Elemental analysis, ESI-MS, (1)H, (13)C, 2D HSQC and COSY NMR spectra confirmed the chemical structure as 5-oxo-2,3-dihydro-5H-[1,3]thiazolo[3,2-a]pyridine-3,7-dicarboxylic acid (TPA).

The improvement of solar photocatalytic activity of ZnO by doping with Er3+:Y3Al5O12 during dye degradation

The Er3+:Y3Al5O12, an upconversion luminescence agent, which is able to transform the visible light to ultraviolet light, was synthesized by nitrate-citric acid method. And then, a novel photocatalyst, Er3+:Y3Al5O12/ZnO composites, was prepared by ultrasonic dispersing and liquid boil method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structural morphology and surface properties of the Er3+:Y3Al5O12/ZnO. Azo Fuchsine dye was selected as target organic pollutant to inspect the photocatalytic activity of Er3+:Y3Al5O12/ZnO. The key parameters affecting the photocatalytic activity of Er3+:Y3Al5O12/ZnO, such as Er3+:Y3Al5O12 content, heat-treatment temperature and heat-treatment time, were studied. In addition, the effects of dye initial concentration, Er3+:Y3Al5O12/ZnO amount and solar light irradiation time were also reviewed, as well as the photocatalytic activity in degradation of other organic dyes were compared. It was found that the photocatalytic activity of Er3+:Y3Al5O12/ZnO was much superior to pure ZnO under the same conditions. Thus, the Er3+:Y3Al5O12/ZnO is a useful photocatalyst for the wastewater treatment because it can efficiently utilize solar light by converting visible light into ultraviolet light.

Effective sonocatalytic degradation of organic dyes by using Er3+:YAlO3/TiO2–SnO2 under ultrasonic irradiation

In this work, the Er3+:YAlO3, as up-conversion luminescence agent, was deposited on the surface of TiO2–SnO2 composite and then a novel sonocatalyst, Er3+:YAlO3/TiO2–SnO2, was obtained. The Er3+:YAlO3/TiO2–SnO2 was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Its sonocatalytic activity was examined through the degradation of Acid Red B under ultrasonic irradiation. The degradation process of Acid Red B was monitored by UV–vis spectrophotometer and ion chromatography. Furthermore, the main influence factors on the sonocatalytic activity of Er3+:YAlO3/TiO2–SnO2 such as Ti/Sn molar ratio, heat-treated temperature and heat-treated time were studied. The results indicate that the Er3+:YAlO3/TiO2–SnO2 with 3:7 Ti/Sn molar ratio heat-treated at 550°C for 60min exhibit a best sonocatalytic activity during the degradation of Acid Red B. In addition, the results also show that Er3+:YAlO3/TiO2–SnO2 displays a good sonocatalytic activity for other organic dyes degradation.

Synthesis of Er3+ loaded barium molybdate nanoparticles: A new approach for harvesting solar energy

Er3+ loaded BaMoO4 was synthesized by the microwave assisted hydrothermal process. Loading of Er3+ ion shifted the absorption band of BaMoO4 towards the longer wavelength and enhanced the absorption of visible light in the solar spectrum. A shift of the absorption edge to the lower energy and four absorption bands located at 390, 489, 524 and, 654nm attributed to the 4f transitions of 4I11/2→2H9/2, 4I15/2→ 4F7/2, 4I15/2→ 2H11/2, and 4I15/2→4F9/2; respectively, were observed during DRS analysis. Moreover, Er3+ ion acts as an upconversion luminescence agent by absorbing near infrared light (NIR) thereby emitting upconversion luminescence. Enhanced absorption of the solar energy has been utilized for the degradation of methylene blue dye as a test reaction. Therefore, this work provides a new approach to harvest solar energy for the activation of scheelite crystal structures.

Preparation of spherical activated carbon-supported and Er3+:YAlO3-doped TiO2 photocatalyst for methyl orange degradation under visible light

In order to develop the high photocatalytic activity of TiO2 under visible light as that under ultraviolet light and make it easy to be separated from treated liquor, a visible light response and spherical activated carbon (SAC) supported photocatalyst doped with upconversion luminescence agent Er3+:YAlO3 was prepared by immobilizing Er3+:YAlO3/TiO2, which was obtained by combination of Er3+:YAlO3 and TiO2 using sol-gel method, on the surface of SAC. The crystal phase composition, surface structure and element distribution, and light absorption of the new photocatalysts were examined by X-ray diffraction (XRD), energy dispersive X-ray spectra (EDS) analysis, scanning electron microscopy (SEM) and fluorescence spectra analysis (FSA). The photocatalytic oxidation activity of the photocatalysts was also evaluated by the photodegradation of methyl orange (MO) in aqueous solution under visible light irradiation from a LED lamp (λ>400 nm). The results showed that Er3+:YAlO3 could perform as the upconversion luminescence agent which converts the visible light up to ultraviolet light. The Er3+:YAlO3/TiO2 calcinated at 700 °C revealed the highest photocatalytic activity. The apparent reaction rate constant could reach 0.0197 min−1 under visible light irradiation.

Preparation of Er3+:Y3Al5O12/TiO2‐ZnO composite and application of solar energy in photocatalytic degradation of organic dyes

The Er3+:Y3Al5O12, which is able to transform the visible light from solar light into ultraviolet light as an upconversion luminescence agent, was prepared by nitrate‐citrate acid and heat‐treated method. And then, a novel photocatalyst, Er3+:Y3Al5O12/TiO2‐ZnO composite, which could effectively utilize the solar energy, was synthesized by ultrasonic dispersion and liquids boil method. In succession, X‐ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structural morphology of the Er3+:Y3Al5O12/TiO2‐ZnO composite. And the degradation performances were also tested by UV‐vis spectrum and Ion chromatograph. To inspect the photocatalytic activity of Er3+:Y3Al5O12/TiO2‐ZnO composite, the Azo Fuchsine dye as target organic pollutant was degraded under solar light irradiation. The key impact parameters on the photocatalytic activity of Er3+:Y3Al5O12/TiO2‐ZnO such as Ti/Zn molar ratio, heat‐treated temperature and heat‐treated time were studied. Otherwise, the effects of dye initial concentration, Er3+:Y3Al5O12/TiO2‐ZnO, solar light irradiation time and other organic dyes were also investigated. It was found that the photocatalytic activity of Er3+:Y3Al5O12/TiO2‐ZnO composite was superior to TiO2‐ZnO powder in the similar system. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 697–704, 2013

ChemInform Abstract: Organometallic Compounds: An Opportunity for Chemical Biology?

AbstractReview: 189 refs.

The influence of Yb, N and F-doped Er3+:Y3Al5O12 on solar light photocatalytic activity of TiO2 for degradation of organic dyes

In this paper, several Yb, N and F-doped up-conversion luminescence agents, Er3+:Y3Al5O12, Er3+:YbnY3−nAl5O12, Er3+:Y3Al5NxO12−x, Er3+:Y3Al5FyO12−y and Er3+:YbnY3−nAl5NxFyO12−x−y, were successfully synthesized by sol–gel method and then their corresponding photocatalysts, Er3+:Y3Al5O12/TiO2, Er3+:YbnY3−nAl5O12/TiO2, Er3+:Y3Al5NxO12−x/TiO2, Er3+:Y3Al5FyO12−y/TiO2 and Er3+:YbnY3−nAl5NxFyO12−x−y/TiO2, were prepared by sol–gel coated method. The samples were characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). UV–vis spectrometer and fluorescence spectrophotometer were used to examine the visible absorption and ultraviolet emission spectra of Yb, N and F-doped up-conversion luminescence agents. Then, the photocatalytic activities of prepared catalysts were reviewed through the degradation of Acid Red B dye in aqueous solution under solar light irradiation. The influences of critical conditions such as doping amount, photocatalyst dose and initial concentration of Acid Red B were studied. In order to check the extensive performance, different organic dyes were used to be degraded by using the same prepared catalysts. In conclusion, Er3+:Yb0.3Y2.7Al5N0.01F0.01O11.98/TiO2 displays highest photocatalytic activity.

Effect of different doped elements on visible light absorption and ultraviolet light emission on Er3+:Y3Al5O12

In this progress report, seven kinds of novel carefully designed and fabricated up-conversion luminescence agents, Er3+:Y3Al5O12, Er3+:YbnY3−nAl5O12, Er3+:Y3BaAl5−aO12, Er3+:Y3GabAl5−bO12, Er3+:Y3Al5NxO12−x, Er3+:Y3Al5FyO12−y and Er3+:YbnY3−nBaGabAl5−a−bNxFyO12−x−y, are successfully synthesized using sol–gel methods. After that, their corresponding photocatalysts, Er3+:Y3Al5O12/TiO2, Er3+:YbnY3−nAl5O12/TiO2, Er3+:Y3BaAl5−aO12/TiO2, Er3+:Y3GabAl5−bO12/TiO2, Er3+:Y3Al5NxO12−x/TiO2, Er3+:Y3Al5FyO12−y/TiO2 and Er3+:YbnY3−nBaGabAl5−a−bNxFyO12−x−y/TiO2, are also prepared by sol–gel coating process. The obtained up-conversion luminescence agents and photocatalysts were characterized by using XRD, XPS, SEM, UV–vis and fluorescence spectrophotometer. Synchronously, several kinds of organic dyes are used to test their photocatalytic degradation using prepared photocatalysts. It indicates that the up-conversion luminescence ability of Er3+:Y3Al5O12 can be improved obviously through doping of some elements. And then, the photocatalytic activity of TiO2 is markedly enhanced by modified up-conversion luminescence agents which can transform much visible light into ultraviolet light.

Organometallic Compounds: An Opportunity for Chemical Biology?

Organometallic compounds are renowned for their remarkable applications in the field of catalysis, but much less is known about their potential in chemical biology. Indeed, such compounds have long been considered to be either unstable under physiological conditions or cytotoxic. As a consequence, little attention has been paid to their possible utilisation for biological purposes. Because of their outstanding physicochemical properties, which include chemical stability, structural diversity and unique photo- and electrochemical properties, however, organometallic compounds have the ability to play a leading role in the field of chemical biology. Indeed, remarkable examples of the use of such compounds-notably as enzyme inhibitors and as luminescent agents-have recently been reported. Here we summarise recent advances in the use of organometallic compounds for chemical biology purposes, an area that we define as "organometallic chemical biology". We also demonstrate that these recent discoveries are only a beginning and that many other organometallic complexes are likely to be found useful in this field of research in the near future.

Site‐Selected Doping of Upconversion Luminescent Er3+ into SrTiO3 for Visible‐Light‐Driven Photocatalytic H2 or O2 Evolution

A series of upconversion luminescent erbium-doped SrTiO(3) (ABO(3)-type) photocatalysts with different initial molar ratios of Sr/Ti have been prepared by a facile polymerized complex method. Er(3+) ions, which were gradually transferred from the A to the B site with increasing Sr/Ti, enabled the absorption of visible light and the generation of high-energy excited states populated by upconversion processes. The local internal fields arising from the dipole moments of the distorted BO(6) octahedra promoted energy transfer from the high-energy excited states of Er(3+) with B-site occupancy to the host SrTiO(3) and thus enhanced the band-to-band transition of the host SrTiO(3). Consequently, the erbium-doped SrTiO(3) species with B-site occupancy showed higher photocatalytic activity than those with A-site occupancy for visible-light-driven H(2) or O(2) evolution in the presence of the corresponding sacrificial reagents. The results generally suggest that the introduction of upconversion luminescent agents into host semiconductors is a promising approach to simultaneously harnessing low-energy photons and maintaining redox ability for photocatalytic H(2) and O(2) evolution and that the site occupancy of doped elements in ABO(3)-type perovskite oxides greatly determines the photocatalytic activity.

Lanthanide (Eu3+, Tb3+, Gd3+) hybrid system with functionalized diethylenetriamine pentaacetic acid: coordination bonding assembly, luminescence and MRI contrast agent property

Abstract A bridge molecule (abbreviated as DTPA-AM, DTPA-bi(4′-acrylamide)) orignated from the diethylenetriamine pentaacetic acid (DTPA) derivative (DTPAA, diethylene-triaminepentaacetic anhydride) after the modification by acrylamide though its amino group group. Subsequently, the lanthanide (Eu 3 + , Tb 3 + , Gd 3 + ) polymer hybrid material systems have been assembled with coordination bonds, which present luminescence for Eu 3 + , Tb 3 + system and MRI (magnetic resonance imaging) contrast agent property for Gd 3 + system, respectively.

Implicit and explicit prior information in near-infrared spectral imaging: accuracy, quantification and diagnostic value

Near-infrared spectroscopy (NIRS) of tissue provides quantification of absorbers, scattering and luminescent agents in bulk tissue through the use of measurement data and assumptions. Prior knowledge can be critical about things such as (i) the tissue shape and/or structure, (ii) spectral constituents, (iii) limits on parameters, (iv) demographic or biomarker data, and (v) biophysical models of the temporal signal shapes. A general framework of NIRS imaging with prior information is presented, showing that prior information datasets could be incorporated at any step in the NIRS process, with the general workflow being: (i) data acquisition, (ii) pre-processing, (iii) forward model, (iv)inversion/reconstruction, (v) post-processing, and (vi) interpretation/diagnosis. Most of the development in NIRS has used ad hoc or empirical implementations of prior information such as pre-measured absorber or fluorophore spectra, or tissue shapes as estimated by additional imaging tools. A comprehensive analysis would examine what prior information maximizes the accuracy in recovery and value for medical diagnosis, when implemented at separate stages of the NIRS sequence. Individual applications of prior information can show increases in accuracy or improved ability to estimate biochemical features of tissue, while other approaches may not. Most beneficial inclusion of prior information has been in the inversion/reconstruction process, because it solves the mathematical intractability. However, it is not clear that this is always the most beneficial stage.

Preparation, characterization and performance of a novel visible light responsive spherical activated carbon-supported and Er 3+:YFeO 3-doped TiO 2 photocatalyst

A novel spherical activated carbon (SAC) supported and Er 3+:YFeO 3-doped TiO 2 visible-light responsive photocatalyst (Er 3+:YFeO 3/TiO 2-SAC) was synthesized by a modified sol–gel method with ultrasonic dispersion. It was characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDS), powder X-ray diffractometer (XRD) and UV–vis diffuse reflectance spectrophotometer (DRS). The photocatalytic activity of Er 3+:YFeO 3/TiO 2-SAC was evaluated for degradation of methyl orange (MO) under visible light irradiation. The effects of calcination temperature and irradiation time on its photocatalytic activity were examined. The experimental results indicated that Er 3+:YFeO 3 could function as an upconversion luminescence agent, enabling photocatalytic degradation of MO by TiO 2 under visible light. The Er 3+:YFeO 3/TiO 2 calcinated at 700 °C showed the highest photocatalytic capability compared to those calcinated at other temperatures. The photocatalytic degradation of MO followed the Langmuir–Hinshelwood kinetic model. Although the photocatalyst showed a good physical stability and could tolerate a shear force up to 25 × 10 −3 N/g, its photocatalytic activity decreased over a four-cycle of reuse in concentrated MO solution, indicating that the decreased activity was ascribed to the fouling of catalyst surface by MO during the degradation process. However, the fouled Er 3+:YFeO 3/TiO 2-SAC could be regenerated through water rinsing-calcination or acid rinsing-calcination treatment.