Single-phased luminescent mesoporous nanoparticles for simultaneous cell imaging and anticancer drug delivery.

Multifunctional materials for biological use have mostly been designed with composite or hybrid nanostructures in which two or more components are incorporated. The present work reports on a multifunctional biomaterial based on single-phased luminescent mesoporous lanthanide oxide nanoparticles that combine simultaneous drug delivery and cell imaging. A simple strategy based on solid-state-chemistry thermal decomposition process was employed to fabricate the spherical mesoporous Gd(2)O(3):Eu nanoparticles with homogeneous size distribution. The porous nanoparticles developed by this strategy possess well-defined mesopores, large pore size and volume, and high specific surface area. The mesoporous features of nanoparticles impart the material with capabilities of loading and releasing the drug with a relatively high loading efficiency and a sustained release behavior of drugs. The DOX-loaded porous Gd(2)O(3) nanoparticles are able to kill the cancer cells efficiently upon incubation with the human cervical carcinoma (HeLa) cells, indicating the potential for treatment of cancer cells. Meanwhile, the intrinsic luminescence of Gd(2)O(3):Eu nanoparticles gives the function of optical imaging. Therefore, the drug release activity and effect of drugs on the cells can be effectively monitored via luminescence of nanoparticles themselves, realizing multifunctionality of simultaneous cell imaging and anticancer drug delivery in a single-phased nanoparticle.

Remarkably enhanced photoluminescence of hexagonal GdPO4.nH2O:Eu with decreasing size.

The hexagonal rhabdophane-type GdPO(4) hydrate (GdPO(4).nH(2)O) was synthesized via a simple hydrothermal process. The size and morphology of the products can be tunable by adjusting the pH of reaction systems through the addition of aqueous NaOH. The nanorods with a width of 50-100 nm and a length of about 1 microm were obtained in the absence of NaOH (pH = 2), while a significant reduction of size (width: approximately 10 nm, length: approximately 50 nm) was observed for the product synthesized in the presence of NaOH (pH = 10). Surprisingly, the small-sized product exhibits a remarkably enhanced photoluminescence quantum yield and long excited state lifetime in comparison with those of the large-sized product. This abnormal luminescence phenomenon is discussed and explained. The EDS and XPS measurements revealed the presence of Na(+) in the small-sized samples. These Na(+) cations were probably bonded to the surface O(2-) dangling bonds, which thus reduces the number of surface defects that usually serve as the nonradiative energy transfer center channels. A considerable reduction of surface defect centers results in the increase of the emission efficiency and excited state lifetime in a small-sized sample. Obviously, the controlled synthesis of rare-earth-doped nanoparticles with a small size, but with relatively strong luminescence, is significant for their applications in the areas of technologies including optoelectronics, sensing and bioimaging.

Synthesis and characterization of new bifunctional nanocomposites possessing upconversion and oxygen-sensing properties.

A new type of bifunctional nanocomposites for biomedical applications, upconversion NaY F(4):Y b(3+), Tm(3+) nanoparticles coated with Ru(II) complex chemically doped SiO(2), has been developed by combining the useful functions of upconversion and oxygen-sensing properties into one nanoparticle. NaY F(4):Y b(3+), Tm(3+) nanoparticles were successfully coated with an Ru(II) complex doped SiO(2) shell with a thickness of approximately 30 nm, and the surface of the SiO(2) was functionalized with amines. The obtained nanocomposites exhibited bright blue upconversion emission, and the luminescent emission intensity of the Ru(II) complex in the nanocomposites was sensitive to oxygen. Compared with the simple mixture of Ru(II) complex and SiO(2), the core-shell nanocomposites showed better linearity between emission intensity of Ru(II) complex and oxygen concentrations. These bifunctional nanocomposites may find applications in biochemical and biomedical fields, such as biolabels and optical oxygen sensors, which can measure the oxygen concentrations in biological fluids.

Nanocrystalline CePO(4):Tb as a novel oxygen sensing material on the basis of its redox responsive reversible luminescence.

This work reports for the first time on a new finding of luminescent CePO(4):Tb nanocrystals providing a novel oxygen sensing material on the basis of the redox responsive reversible luminescence in an oxidizing/reducing atmosphere. The origin of the luminescence quenching/recovery of nanocrystalline CePO(4):Tb was clearly demonstrated, from the surface chemistry of nanocrystals and the fluorescence decay dynamics of Tb(III). Our present work represents a preliminary demonstration of the feasibility of using nanocrystalline CePO(4):Tb as a novel oxygen sensing material since it yields several advantages including surfactant-free synthesis, dual detection functioning, rapid response, high sensitivity and good reproducibility.

Improved upconversion luminescence properties of Gd2O3:Er3+/Gd2O3:Yb3+ core-shell nanorods.

The Gd2O3:Er3+/Gd2O3:Yb3+ core-shell nanorods (NRs) as well as Er3+ and Yb3+ homogeneously codoped Gd2O3 NRs were synthesized by the hydrothermal method. The average diameters of the NRs are approximately 20 nm and the lengths are 150-200 nm. The thickness of the Gd2O3:Yb3+ shells on the Gd2O3:Er3+ cores are approximately 5 nm. The upconversion luminescence (UCL) properties of the core-shell NRs have been studied in contrast to homogeneously codoped NRs under 978-nm laser diode excitation. Green emissions of 2H11/2, 4S3/2-4I15/2, and red emissions of 4F9/2-4I15/2 were observed. Relative intensity of the red (4F9/2-4I15/2) to the green (4S3/2/2H11/2-4I15/2) and the intensity ratio (RHS) of 2H11/2-4I15/2 to 2H11/2-4I15/2 decrease obviously in the core-shell NRs compared to the NRs. The power-dependence of UCL intensity and the thermal effect caused by 978-nm diode laser irradiation was studied. The result indicates that the cross-relaxation effect and the thermal effect in the core-shell structure is effectively depressed.

CdS/Cyclohexylamine inorganic-organic hybrid semiconductor nanofibers with strong quantum confinement effect.

Inorganic-organic hybrid semiconductor nanofibers of CdS/CHA (CHA = cyclohexylamine) were successfully synthesized by a simple solvothermal method. The fibers obtained had average diameter of 20 nm and length of several micrometers. In these fibers, periodic layer-like sub-nanometer structures with thickness of approximately 3 nm were identified by high-resolution transmission electron microscope (HR-TEM). The absorption of the hybrids exhibited a large blue-shift in contrast to the bulk, which was attributed to strong quantum confinement effect (QCE) induced by internal sub-nanometer structures. Pure hexagonal wurtzite CdS (H-CdS) nanorods were also obtained by extracting the CdS/CHA hybrids with dimethyl formamide (DMF). The rods obtained had average diameter of 20 nm and length of 200 nm. A CdS/CHA/polyvinyl alcohol (PVA) composite film emitting white light was prepared by spin coating.

Upconversion white light devices: Ln(3+)-tridoped NaYF4 nanoparticles and PVP modified films.

Upconversion (UC) white light hybrid thin films containing Ln(3+)-tridoped (Yb3+, Er3+ and Tm3+) NaYF4 nanoparticles and poly(vinyl pyrrolidone) (PVP, M(w) approximately 1300000) were prepared by a spin-coating method and characterized by X-ray diffraction (XRD), field emission scanning electron micrograph (FE-SEM) and Fourier transform infrared spectra (FT-IR). White light was generated by two different lanthanide ions, Er3+ (red and green) and Tm3+ (blue) under excitation by a 980-nm laser diode. Due to the modification of PVP to the UC populating processes, the color stability of the white light in the hybrid films was remarkably improved.

Preparation, characterization and photoluminescence properties of ternary europium complexes Eu(DBM)3bath encapsulated into aluminosilicate zeolites.

To modify the photoluminescence properties the Eu(DBM)3bath complexes were encapsulated into the sub-nanometer pores of aluminosilicates zeolites L and Y and characterized by X-ray diffraction (XRD), transmission electron micrographs (TEM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet-visible (UV-vis) absorption spectra. The luminescent properties of the encapsulated composites (Eu-L and Eu-Y) were systematically studied. The results indicate that in both the two composites the crystal-field symmetry becomes lower, as a consequence, the 5D0-7F2 electronic-dipole transition relative to the 5D0-7F1 magnetic-dipole transition of Eu3+ increases in contrast to the pure complexes. The outer quantum efficiency of the Eu3+ emission and the photostability of Eu3+ are both improved considerably. The adsorption of water in the composites has influence on the thermostability and decay dynamics of the Eu3+ emission. In the composite Eu-L, which contains less water the thermostability of luminescence is improved considerably and the lifetime becomes longer in comparison to the pure complexes. Overall, zeolite L is a more ideal host material for modification of lanthanide complexes.

Europium(III) complexes/silica hybrid nanospheres synthesized in microemulsion.

Eu(DBM)3Phen/silica nanospheres with a uniform diameter of approximately 40 nm and the characteristic fluorescence of Eu3+ ions have been synthesized by a microemulsion method. SEM and TEM analysis indicate that the hybrid nanospheres are core/shell structures with fine spherical surfaces and that Eu(DBM)3Phen has been successfully enveloped in the SiO2 spheres as chromophore cores. IR absorption spectra and photoluminescence spectra suggest that the hybrid nanoparticles are promising materials for bioassay.

White luminescence by up-conversion from thin film made with Ln(3+)-doped NaYF4 nanoparticles.

White light-emitting thin films containing Ln(3+)-doped NaYF4 nanoparticles were prepared by a simple spin-coating method. White light was generated by two different lanthanide ions, Er3+ (red and green) and Tm3+ (blue), by upconversion process under the excitation of a 980-nm laser diode. The ratio of the intensity of the three main emissions was tuned by controlling the concentration of the nanoparticles in the thin film and the concentration of the lanthanide ions in the nanoparticles. The color coordinates corresponding to emissions of different nanoparticle concentrations and with the different pump powers were investigated. When the pump power was fixed at 900 mW, the thin film with a concentration ratio of 2.5:1 emitted pure white light with coordinates of (0.333, 0.339).

Improved luminescence properties of europium complexes encapsulated into mesoporous SBA-15.

Two kinds of Eu3+ COmplexes-Eu(TTA)3(TPPO)2 (TTA: thenoyltrifluoroacetone, TPPO: triphenylphosphineoxide) and Eu(BA)3(TPPO)2 (BA: 1-benzoylacetone)-were fully encapsulated, uniformly distributed into the channels of unmodified and modified SBA-15, and structurally characterized. The luminescent properties of the encapsulated complexes were systematically studied in contrast to the pure complexes. The results indicate that the excitation bands assigned to the pi-pi* electron transition of the ligands for Eu3+ complexes encapsulated in SBA-15 were split into different components, and the 5D0-7F0 transitions became partly allowed. The emission lines for the 5D0-7F2 transitions became broader and the relative intensity for different crystal field components varied greatly in comparison to the pure complex. Most importantly, the photostability and thermostability of the emissions improved considerably.

[A novel red phosphor (La3PO7:Eu3+) prepared by solid state method].

Novel red phosphor, Eu3+ -doped oxyphosphate (La3 PO7:Eu3+), was synthesized by a solid state method under high temperature. All the starting materials were analytical grade. La2O3, EuO3 and (NH4)2HPO4 weighed in appropriated molar ratios and ground in an agate mortar. Then the powder was treated under 1000 degrees C. The crystal phase of La3PO7:Eu3+ was investigated by X-ray diffraction (XRD) using a Cu target radiation resource (lamda = 1.54078 ?) and exhibited prominent peaks accordant with JCPDS standard card (33-0720) of La3PO7 in monoclinic phase. Emission and excitation spectra of La3PO7:Eu3+ were recorded at room temperature using a fluorescence spectrometer (Hitachi F-4500). Under 254 nm excitation, intense red fluorescence was observed from La3PO7:Eu3+, which was assigned to the (5)D0-->(7)F2 transition of Eu3+ ions. The intensity of the (5)D0-->(7)F2 transition is stronger than that of the (5)D0-->(7)F1 transition, showing that the Eu3+ ions were in the non-centrosym-metric sites in La3PO7. The CommissionIn-ternational DeL" Eclairage (CIE) coordinate of La3PO7:Eu3+ is (0.63,0.37) in the red area of CIE1931 XY chromaticity coordinate graph and close to that of Y2o3:Eu3+, but the cost of La3PO7 host is lower. This novel material may have potential applications in plasma display panels and Hg-free fluorescent lamps in the future.

Synthesis and characterization of a new trifunctional magnetic-photoluminescent-oxygen-sensing nanomaterial.

Magnetic Fe(2)O(3) nanoparticles coated with SiO(2) chemically doped with a Ru(II) complex were prepared using a simple solution based method. Field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) showed that the Fe(2)O(3) nanoparticles with a mean diameter of ∼115 nm were successfully coated with Ru(II) complex-chemically doped SiO(2) shell with a thickness of ∼30 nm. The obtained nanocomposite material showed a strong magnetic response to a varying magnetic field, exhibited the bright red triplet metal-to-ligand charge transfer ((3)MLCT) emission, and its photoluminescent intensity was sensitive to oxygen concentration. Compared with the Ru(II) complex in silica gels, the Ru(II) complex in the magnetic-optical-oxygen-sensing nanocomposite demonstrated improved thermodynamic stability of emissions. These nanocomposites are also nontoxic and easily conjugated with biomolecules. Their magnetic, photoluminescent and oxygen-sensing properties make them promising candidates for cell separation, biomarkers and optical oxygen sensors, which can measure the O(2) concentration in biological bodies.

Fabrication and photoluminescent properties of Gd2O3 : EU3+ nanowires in AAO template.

Uniform Gd2O3 : Eu3+ nanowires were fabricated by using anodic aluminum oxide template (AAO). The spectral measurements indicate that with the increasing annealing temperature the excitation band of Eu3+ in Gd2O3 : Eu3+ nanowires/AAO shifted blue, the intensity ratio of 5D0-7F2 to 5D0-7F1, decreased, and the lifetime became longer. In the sample annealed at 1000 degrees C two spectral components, the sharper and broader lines were identified, corresponding to two different local environments, the Eu3+ ions in cubic phase and in amorphous phase, respectively. The 5D0-7F1 transitions of Eu3+ ions in cubic phase had longer lifetime than that in amorphous phase. In contrast to the lifetime of the 5D0-7F(j) transitions in the bulk, that in Gd2O3 : Eu3+/AAO composite films increased due to influence of the surrounding media (AAO).

Structure and photoluminescent properties of microstructural YBO3 : Eu3+ nanocrystals.

YBO3 : Eu3+ nanocrystals (NCs) were prepared by a hydrothermal method and characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The results demonstrate that morphology and structure of the NCs varied strongly with hydrothermal temperature. Their luminescent properties were investigated in comparison to the bulk. A large number of NO3- groups were adsorbed at the surface of hydrothermal products, which acted as luminescent killers; Two symmetry sites of Eu3+ ions in NCs, the interior and the surface sites, were identified by the site-selective excitation and time-resolved emission experiments; The intensity ratio of 5D0-7F2 to 5D0-7F, of EU3+ at the surface site increased greatly than that at the interior site; as a result, the chromaticity was improved; The total radiative transition rate of 5D0-sigmaJ7FJ for Eu3+ at the surface site was 3-5 times larger than that at the interior.

Evidence for visible quantum cutting via energy transfer in SrAl12O19:Pr,Cr.

Evidence for visible quantum cutting involving the emission of two visible photons for each vacuum-ultraviolet (VUV) photon absorbed is demonstrated in SrAl(12)O(19):Pr,Cr using synchrotron radiation as one of the excitation sources. Upon VUV excitation of the 4f5d states of Pr(3+), quantum cutting could occur by a two-step energy transfer from Pr(3+) to Cr(3+) by cross relaxation and sequential transfer of the remaining excitation energy. A theoretical visible quantum efficiency of 147% is estimated in SrAl(12)O(19):2% Pr,5% Cr, suggesting the possibility of a VUV phosphor with visible quantum efficiency higher than 100% based on Pr(3+)-Cr(3+) pair in oxide materials.

Spectroscopic investigation of CaAl12O19:M³âº upon UV/vacuum-UV excitation: a comparison with SrAl12O19:M³âº (M = Pr,Cr).

In order to evaluate the possibility of using Cr³âº co-doping to modify the emission properties of Pr³âº-based quantum cutting phosphors, which emit one ultraviolet (UV) and one visible photon from each vacuum-UV photon absorbed, into phosphors that emit two visible photons, the optical spectroscopies between 150 and 750 nm of CaAl12O19:M³âº (M = Pr,Cr) were investigated and compared with those of SrAl12O19:M³âº using synchrotron radiation as one of the excitation sources. When Pr³âº is excited to its 4f5d states, cascade emission of UV photons from the ¹S0 state followed by visible photons from the ³P0 state are both observed in (Ca,Sr)Al12O19:Pr³âº. Similar to SrAl12O19:M³âº, there exist desirable spectral overlaps between Pr³âº ¹S0 emissions and the Cr³âº higher multiplet absorptions in CaAl12O19, which should be favourable to the energy transfer from Pr³âº ¹S0 to Cr³âº, converting the UV photon from Pr³âº ¹S0 into the red Cr³âº emission. However, the host absorption band and the Cr³âº-related charge transfer band have an unfavourable overlap with the Pr³âº 4f5d states in the vacuum-UV region, preventing efficient selective Pr³âº excitation under radiation of Xe discharge, a prerequisite for the quantum cutting process.

Improved photoluminescence properties of ternary terbium complexes in mesoporous molecule sieves.

Ternary terbium complexes were fully encapsulated and uniformly distributed into the channels of unmodified and modified mesoporous molecule sieves of SBA-15 and characterized by transmission electron micrographs (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis) absorption spectra, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and elemental analysis. The luminescent properties for the encapsulated complexes were systematically studied in contrast to the pure complexes, including excitation and emission spectra, fluorescence dynamics, photostability under UV exposure, and the temperature dependence of intensity and lifetime. The results indicate that the excitation bands assigned to the pi-pi* electron transition of the ligands for Tb complexes encapsulated in SBA-15 were split into different components due to decreased symmetry and disappeared at long wavelengths. Owing to suppressed vibration transitions, the outer quantum efficiency of the 5D4-7FJ (J = 0-5) emissions was enhanced largely in comparison to the pure complexes. In addition, the photostability and thermostability of the emissions were also improved considerably.

Solvothermal synthesis and photoluminescent properties of ZnS/cyclohexylamine: inorganic-organic hybrid semiconductor nanowires.

An inorganic-organic hybrid semiconductor, ZnS/CHA (CHA = cyclohexylamine) nanocomposites was successfully synthesized via a solvothermal method using CHA as solvent, which yielded uniform and ultralong nanowires with widths of 100-1000 nm and lengths of 5-20 microm. Changing the reaction conditions could alter the morphology and optical properties of the nanocomposites. The periodic layer subnanometer structures were identified by high-resolution transmission electron microscopy (HR-TEM) images, with thickness of approximately 2 nm. The composites exhibited a very large blue-shift in their optical absorption edge as well as an exciton excitation band due to a strong quantum confinement effect caused by the internal subnanometer-scale structures. The pure hexagonal wurtzite ZnS nanowires were also obtained by extracting the ZnS/CHA nanocomposites with dimethyl formamide (DMF). In addition, the luminescent properties of exciton and defect-related transitions in different samples of ZnS/CHA were discussed in detail.

[High efficiency and low threshold upconversion from IR to red for Er3+ and Tm3+ co-doped fluoride-oxide glass-ceramic].

In this paper, high efficiency and low threshold upconversion from IR to red is reported, for Er3+ and Tm3+ co-doped fluoride-oxide glass-ceramic under 978 nm LD excitation. The component of sample in experiment is 65GeO2-25NaF-8.5BaF2-1Er2O3-0.5 Tm2O3, and the prepared method is obtained. The upconversion emission spectra under 978 nm LD excitation is measured at room temperature. Analyzing it, we find that introduction of Tm3+ into Er3+ doped system preferentially quenches the green upconversion fluorescence from 4S3/2 level of Er3+ duo to the efficient cross-relaxation of 4I13/2-->4I15/2 (Er): 3H6-->3H4 (Tm) which can significantly reduce the upconversion efficiency from 4I13/2 level to the emitting 4S3/2 level, and the Tm3+ behaves as a good sensitizer of the red upconversion from the 4F9/2 level of Er3+ which is mainly populated by the cross-relaxation of 3H4-->3H6 (Tm): 4I11/2-->4F9/2 (Er). However, at low Er3+ concentration (2 mol%), it is impossible for strong red upconversion. X-ray analysis is done, there are lots of nanocrystallites in MFG glass-ceramic. So we think, this red upconversion is attributed to Er3+ enriched fluoride microcrystallites, which makes the cross-relaxation of 3H4-->3H6 (Tm): 4I11/2-->4F9/2 (Er) more effective, therefore their active optical properties may be optimised. In the end, the relationship between LD working current and intensity of upconversion luminescence is discussed, the results confirm that both red and green upconversion processes are consisted by two photons.