One-dimensional SrWO4:Eu(3+) nanostructures were prepared by a hydrothermal method. The structures and morphologies of the nanocrystals were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The results indicated that the phase compositions, morphologies and sizes and luminescence properties of SrWO4:Eu(3+) are related to the initial reactant content and reaction time, and lower initial reactant content is beneficial for the formation of the string SrWO4:Eu(3+) nanobeans. The photoluminescence properties of SrWO4:Eu(3+) were investigated in detail. In the emission spectra of SrWO4:Eu(3+), the (5)D0→(7)F1 is dominant when the excitation wavelength is 295 nm, while the (5)D0→(7)F2 is dominant when the excitation wavelengths are in the range of 363-537 nm. Obviously, the string SrWO4:Eu(3+) nanobeans have multiple luminescence centers or emitting states. The excitation spectra of SrWO4:Eu(3+) contain several sharp peaks attributed to f-f transitions of Eu(3+) ions and a broad excitation band assigned to the overlap of WO4(3-) absorption and charge transfer transition between Eu(3+) and O(2-). The intensity ratio of the broad excitation band to the sharp excitation peaks changed with the emission wavelength as well as the Eu(3+) content. In addition, Eu(3+) ions occupy higher symmetry sites in SrWO4:Eu(3+) nanocrystals with increasing the particle size of nanocrystals. The effect of Tb(3+) as well as Gd(3+) ions on the photoluminescence of SrWO4:Eu(3+) was also investigated.
Y(OH)3:Eu(3+) nanotubes were synthesized by a facile hydrothermal method first, and then Au particles were grown on the surface of Y2O3:Eu(3+) nanotubes by combining the vacuum extraction method and the annealing process. The composite nanotubes were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The effects of the Au content on the photoluminescence properties of the Au/Y2O3:Eu(3+) composite nanotubes were investigated in detail. In the excitation spectra of Au/Y2O3:Eu(3+) monitored at 614 nm, the (7)F0→(5)H3 transition from Eu(3+) increased with increasing Au content, while the other sharp lines originating from Eu(3+) f-f electron transitions almost vanished. In the emission spectra, the spectral configurations of Eu(3+) in Au/Y2O3:Eu(3+) composite nanotubes varied with the excitation wavelengths. When the excitation wavelength was 256 nm, the (5)D4→(7)F0, (5)D7→(7)F0, (5)G2→(7)F0, (5)L6→(7)F0, (5)D0→(7)F0, (5)D0→(7)F1, (5)D0→(7)F2, (5)D0→(7)F3, and (5)D0→(7)F4 transitions from Eu(3+) ions in Au/Y2O3:Eu(3+) were observed. When the excitation wavelength was 378 nm, the plasmon resonance peak from Au nanoparticles was observed. In addition, 4-ATP was chosen as the model molecule to examine the performance of the Au/Y2O3:Eu(3+) composite nanotubes as SERS substrates. The relative intensities of the SERS spectra enhanced with the increase of Au(+) : Ln(3+) ratio.
In this study, we prepared new lignin-based pH-responsive
nanoparticles
(LG-M(N)-PEG NPs) and their conjugates (LG-M(N-DOX)-PEG NPs) by using
polyethylene glycol (PEG), doxorubicin (DOX), and alkaline lignin.
In these NPs, the PEG chains were conjugated to lignin by an UV irradiated
thiol–ene click reaction. The hydrazine and β-thiopropionate
bonds in the NPs could conduct pH-triggered release of both DOX and
lignin at an acidic pH in the tumor cells. Results showed that LG-M(N-DOX)-PEG
NPs had a moderate particle size (48.3 ± 3.2 nm), significant
cytotoxicity against 4T1 cells, and enhanced cellular uptake. Interestingly,
the NPs without DOX (LG-M(N)-PEG NPs) could increase intracellular
reactive oxygen species generation, induce cell pyroptosis, and result
in a selective cytotoxicity to cancer cells. While the LG-M(N-DOX)-PEG
NPs could deliver both lignin and DOX, they had favorable carrier-enhanced
cytotoxicity and higher cancer cellular uptake compared to free DOX.
Moreover, LG-M(N-DOX)-PEG NPs exhibited a clear tumor-inhibiting effect
in vivo. Therefore, the NPs described here have great potential application
in the drug delivery system.
Y(OH) 3 :Eu 3+ nanotubes were synthesized using a facile hydrothermal method, and then, Pt particles were grown on the surface of the nanotubes using a combination of vacuum extraction and annealing. The resulting Pt/Y 2 O 3 :Eu 3+ composite nanotubes not only exhibited enhanced red luminescence under 255-or 468-nm excitation but could also be used to improve the efficiency of dyesensitized solar cells, resulting in an efficiency of 8.33%, which represents a significant enhancement of 11.96% compared with a solar cell without the composite nanotubes. Electrochemical impedance spectroscopy results indicated that the interfacial resistance of the TiO 2 -dye|I 3 -/I -electrolyte interface of the TiO 2 -Pt/Y 2 O 3 :Eu 3+ composite cell was much smaller than that of a pure TiO2 cell. In addition, the TiO 2 -Pt/Y 2 O 3 :Eu 3+ composite cell exhibited a shorter electron transport time and longer electron recombination time than the pure TiO 2 cell.
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