Rationally designed upconversion nanoparticles for NIR light-controlled lysosomal escape and nucleus-based photodynamic therapy.

Cell nucleus-based photodynamic therapy is a highly effective method for cancer therapy, but it is still challenging to design nucleus-targeting photosensitizers. Here, we propose the "one treatment, multiple irradiations" strategy to achieve nucleus-based photodynamic therapy using the photosensitizer rose bengal (RB)-loaded and mesoporous silica-coated upconversion nanoparticles with the surface modification of amine group (UCNP/RB@mSiO2-NH2 NPs). After implementation into cancer cells, the rationally designed UCNP/RB@mSiO2-NH2 NPs could be specifically accumulated in the acidic lysosomes due to their amino group-decorated surface. Upon a short-term (3 min) irradiation of 980 nm near-infrared light, the reactive oxygen species produced by RB through the Förster resonance energy transfer between the upconversion nanoparticles and RB molecules could effectively destroy lysosomes, followed by the release of the UCNP/RB@mSiO2-NH2 NPs from the lysosomes. Subsequently, these released UCNP/RB@mSiO2-NH2 NPs could be transferred into the cell nucleus, where a second 980 nm light irradiation was conducted to achieve the nucleus-based photodynamic therapy. The rationally designed UCNP/RB@mSiO2-NH2 NPs showed excellent anticancer performance in both two-dimensional and three-dimensional cell models using the "one treatment, multiple irradiations" strategy.

Optimising FRET-efficiency of Nd3+-sensitised upconversion nanocomposites by shortening the emitter-photosensitizer distance.

Nd3+-Sensitised luminescent upconversion nanoparticles (UCNPs) have gained interest recently as theranostics due to their near-infrared (NIR) light excitation with a better tissue penetration depth. One example is the core/shell design NaYF4:Yb,Er@Nd,Yb. When harvesting the upconversion energy in such architectures, the long emitter-photosensitizer (i.e. Er3+-PS) distances lead to inefficient Förster resonance energy transfer (FRET). Herein, we report a new nanocomposite NaYF4:Nd,Yb@Yb@Yb,Er@Y with Nd3+ ions in the core and Er3+ ions in the shell to shorten the Er-PS distance to achieve better FRET. Furthermore, an outer non-emitting protective Y3+ shell and a conducting Yb3+ shell reduced surface quenching and Er3+-to-Nd3+ energy back transfer effects, respectively. The upconversion FRET and downshifting emission efficiencies were simultaneously optimised by adjusting the thickness of the Y3+ shell, and the FRET efficiency was at least 3.7 times that of the reference NaYF4:Yb,Er@Yb@Nd,Yb@Y in a photodynamic therapy (PDT) model.

Recent Progress in Fluorescence Imaging of the Near-Infrared†II Window.

Near-infrared (NIR) fluorescent materials are considered to be the most promising labeling reagents for sensitive determination and biological imaging due to the advantages of lower background noise, deeper penetrating capacity, and less destructive effects on the biomatrix over those of UV and visible fluorophores. In the past decade, advances in biomedical fluorescence imaging in the NIR region have focused on the traditional NIR window (NIR-I; λ=700-900 nm), and have recently been extended to the second NIR window (NIR-II; λ=1000-1700 nm). In vivo NIR-II fluorescence imaging outperforms imaging in the NIR-I window as a result of further reduced absorption, tissue autofluorescence, and scattering. In this review, the applications of four types of NIR-II fluorescent materials, organic fluorophores, quantum dots, rare-earth compounds, and single-walled carbon nanotubes, are summarized and future trends are discussed. Some methods to enhance the NIR-II fluorescence quantum yield are also proposed.

Thoron progeny size distribution in monazite storage facility.

Field experiments in the atmosphere of monazite warehouses with a high content of (220)Rn progeny concentration were conducted. Size distribution of aerosol particles was measured with the combined use of diffusion battery with varied capture elements and cascade impactor. Four (212)Pb aerosol modes were detected-three in the ultrafine region (aerosol median thermodynamic diameters ∼0.3, 1 and 5 nm) and one with an aerosol median aerodynamic diameter of 500 nm. The activity fraction of aerosol particles with the size <10 nm is nearly 20-25 %. The dose conversion factor for EEC220Rn exposure, obtained on the basis of the aerosol size distribution and existing research data on lung absorption types of (212)Pb aerosols, is close to 180 nSv per Bq h m(-3).

Rare-earth metal oxide doped transparent mesoporous silica plates under non-aqueous condition as a potential UV sensor.

Transparent mesoporous silica plates doped with rare-earth metal oxide were prepared using solvent-evaporation method based on the self-organization between structure-directing agent and silicate in a non-aqueous solvent. A triblock copolymer, Pluronic (F127 or P123), was used as the structure-directing agent, while tetraethyl orthosilicate (TEOS) was used as a silica source. The pore diameter and the surface area of the mesoporous silica plate prepared with the optimized conditions were ca 40 A and 600 m2 g(-1), respectively, for both structure-directing agent. Rare-earth metal oxides (Eu, Tb, Tm oxide) in mesochannel were formed via one-step synthetic route based on the preparation method of a silica plate. Optical properties of rare-earth metal oxide-doped mesoporous silica plates were investigated by UV irradiation and photoluminescence (PL) spectroscopy. Under the exitation wavelength of 254 nm, the doped mesoporous silica plates emitted red, green and blue for Eu, Tb and Tm oxides, respectively. Rare-earth metal oxide-doped mesoporous silica plates showed enhanced PL intensity compared to that of the bulk rare-earth metal oxide.

Blue photoluminescence, greenish-blue afterglow and their Ti-concentration dependence in rare earth-free bazirite-type BaZr1-xTixSi3O9.

We synthesized Ti-bearing bazirite (BaZr(1-x)Ti(x)Si(3)O(9), x=0-0.2) and examined their spectroscopic features comprehensively, in order to elucidate the photoluminescent properties in the bazirite phase. Strong emission around 2.79 eV was observed in the synthetic bazirite phase with x=0.01 by UV excitation, which exhibited an internal quantum yield of 72% at room temperature. In addition, the bazirite phases also showed clear afterglow with peak around 2.62 eV in the range of x=0.005-0.03, whereas no afterglow property was confirmed in Ti-bearing pabstite (BaSnSi(3)O(9)) phases, in spite of being isostructural of bazirite. It was demonstrated that presence of Zr-related center is a necessary condition for evolution of the afterglow property in the bazirite structure.

Nanofabricated upconversion nanoparticles for photodynamic therapy.

We present a novel process for the production of three-layer Composite Nanoparticles (CNPs) in the size range 100-300 nm with an up-converting phosphor interior, a coating of porphyrin photosensitizer, and a biocompatible PEG outer layer to prevent clearance by the reticuloendothelial system. We show that these CNPs produce millimolar amounts of singlet oxygen at NIR intensities far less than other two-photon techniques.

Observations of self-induced ultraslow light in a persistent spectral hole burning medium.

We present observations of self induced ultraslow light in a persistent spectral hole-burning rare-earth doped crystal. The observed group delay (velocity) is as long as 40 micros (75 m/s), which is comparable to that obtained using electromagnetically induced transparency or coherent population oscillations. We analyze the observed ultraslow light as a function of frequency detuning, light intensity, and atom population (oscillator strength). The present observation of ultraslow light in a persistent spectral hole-burning medium gives potentials to all-optical information processing such as on-demand all-optical buffer memories.

Anti-Stokes luminescence cooling of Tm3+ doped BaY2F8.

We report laser-induced cooling with thulium-doped BaY2F8 single crystals grown using the Czochralski technique. The spectroscopic characterization of the crystals has been used to evaluate the laser cooling performance of the samples. Cooling by 3 degrees below ambient temperature is obtained in a single-pass geometry with 4.4 Watts of pump laser power at lambda = 1855 nm.

Optimization of Pr3+, Tb3+, and Sm3+ co-doped (Y0.65Gd0.35)BO3:Eu0.05(3+) VUV phosphors through combinatorial approach.

A combinatorial approach was used to systematically investigate the effect of trace Pr(3+), Tb(3+), or Sm(3+) on the VUV photoluminescence of Eu(3+) in the Pr(3+), Tb(3+), or Sm(3+) co-doped (Y(0.65)Gd(0.35))BO(3):E(3+)(0.05). We found that Pr(3+) and Tb(3+)increases the VUV photoluminescent efficiency, while Sm(3+) decreases the efficiency. The optimized composition was identified to be between 7 x 10(-6) and 3 x 10(-4), and the corresponding efficiency improvement is about 15%. Scale-up experiments confirmed the results in the combinatorial materials libraries.

Recent progress on elaboration of undoped and doped Y2O3, Gd2O3 rare-earth nano-oxide.

Some selected materials with small sizes in the nanometer region are reviewed. Different methods for synthesis of nanoscale materials are classified and discussed. Basic prerequisites for successful use of the materials for nanotechnology application are their synthesis with specific and homogeneous composition and geometry. This review summarizes recent results on nanoscale materials containing optically active lanthanide ion especially focused on Y2O3 and Gd2O3 oxide.

The origin of highly efficient selective emission in rare-earth oxides for thermophotovoltaic applications.

Rare-earth oxide materials emit thermal radiation in a narrow spectral region, and can be used for a variety of different high-temperature applications, such as the generation of electricity by thermophotovoltaic conversion of thermal radiation. However, because a detailed understanding of the mechanism of selective emission from rare-earth atoms has so far been missing, attempts to engineer selective emitters have relied mainly on empirical approaches. In this work, we present a new quantum thermodynamic model to describe the mechanisms of thermal pumping and radiative de-excitation in rare-earth oxide materials. By evaluating the effects of the local crystal-field symmetry around a rare-earth ion, this model clearly explains how and why only some of the room-temperature absorption peaks give rise to highly efficient emission bands at high temperature (1,000-1,500 degrees C). High-temperature emissivity measurements along with photoluminescence and cathodoluminescence results confirm the predictions of the theory.

Thermoluminescent and dosimetric properties of X ray phosphors.

Rare earth doped oxide, phosphate, etc. are radioluminescent phosphors that have a broad application in X ray imaging, in luminescent screens, image transformers and in fluorescent lamp manufacturing. Some of them have interesting thermoluminescence features as well, which makes the phosphors applicable also in dosimetry. Two of these materials are Sr3(PO4)2 and BaFCl activated with europium. The general radioluminescence (RL) and thermoluminescence (TL) characteristics of these materials was investigated earlier and the preliminary results have already been published elsewhere. The aim of the present work is to investigate the interesting properties of these phosphors mainly from a dosimetric point of view (sensitivity, dose dependence, etc.).

Consideraçöes sobre a toxidez química e radiológica das terras raras / Chemical and radiological toxicity of rare earths

A concentraçäo máxima permissível de uma mistura de terras raras no ar do local de trabalho foi calculada em 1,47 mg/m de ar. Este valor foi obtido tendo-se levado em conta a meia-vida biológica desses elementos no corpo humano e dados de intoxicaçäo aguda. É apresentado um modelo matemático simplificado para exprimir o conteúdo desse produto no corpo em funçäo do tempo, para intoxicaçäo crônica, via inalaçäo de aerodispersóides. Sob o ponto de vista puramente radiológico, o limite calculado é da ordem de 100 mg/m de ar, mostrando que a toxidez química desses produtos é preponderante