Long wavelength luminescent NaYF4:Yb,Er/NaGdF4 core–shell upconversion nanoparticles that were synthesized and modified with poly(acrylic acid) (PAA) were used to detect sulfide ions. The NaYF4:Yb,Er/NaGdF4 core–shell upconversion nanoparticles were synthesized to give an emission peak in the red-light region. When the carboxyl-functionalized NaYF4:Yb,Er/NaGdF4 core–shell upconversion nanoparticles and cupric ions (Cu2+) were mixed, the luminescence was quenched because of coordination between the carboxyl of PAA and Cu2+. However, when sulfide ions were added into the system, due to the competitive binding between S2− and Cu2+, the luminescence of the NaYF4:Yb,Er/NaGdF4 core–shell upconversion nanoparticles was recovered. Based on the recovery of the luminescence intensity, a turn-on system for the detection of sulfide ions was designed. Under optimal conditions, the linear range for the detection of sulfide ions ranged from 2.63 × 10−2 to 2.25 × 102 μM (R = 0.99) with a limit of detection for sulfide ions as low as 2.20 × 10−2 μM. The method was successfully applied to sulfide ion sensing in different environments.
Introducing upconversion nanoparticles (UCNPs) or fabricating TiO 2 hollow spheres (TiO 2 -HSs) are considered two feasible strategies to enhance the photovoltaic performance of dye-sensitized solar cells (DSSCs). However, studies investigating a combination of UCNPs and TiO 2 -HSs for the application in DSSCs are still scarce. In this contribution, NaYF 4 :Yb,Er@NaGdF 4 :Nd@SiO 2 UCNPs and TiO 2 -HSs were synthesized and respectively applied as upconversion layers and scattering layers on the TiO 2 photoanode of DSSCs. The influence of different doping ratios of UCNPs on cell performance was explored. The present results reveal that the DSSCs device based on conventional P25 photoanode films incorporating the UCNPs with 10% can achieve a photovoltaic efficiency of 6.65%, showing 29.63% enhancement in comparison to the device without UCNPs. When the TiO 2 -HSs are used as scattering layers above the P25 film, the DSSCs device obtains a higher photovoltaic efficiency of 6.97%. More importantly, combining the UCNPs and TiO 2 -HSs can further enhance the photoelectrical property of DSSCs, realizing an optimal efficiency of 8.17%. Such an improvement can be attributed to a synergistic mechanism arising from the upconversion effect of UCNPs and the light scattering effect of TiO 2 -HSs. This work opens a new way of preparing composite photoanode films to improve the photovoltaic performances of DSSCs.
Multidrug resistance (MDR) of cancers is still a major challenge, and it is very important to develop visualized nanoprobes for the diagnosis and treatment of drug resistant cancers. In this work, we developed a multifunctional delivery system based on DOX-encapsulated NaYF4:Yb/Er@NaGdF4 yolk–shell nanostructures for simultaneous dual-modal imaging and enhanced chemotherapy in drug resistant breast cancer. Using the large pore volume of the nanostructure, the delivery system had a high loading efficiency and excellent stability. Also, an in vitro and in vivo toxicity study showed the good biocompatibility of the as-prepared yolk–shell nanomaterials. Moreover, by nanocarrier delivery, the uptake of DOX could be greatly increased in drug resistant MCF-7/ADR cells. Compared with free DOX, the as-prepared delivery system enhanced the chemotherapy efficacy against MCF-7/ADR cells, indicating the excellent capability for overcoming MDR. Furthermore, core–shell NaYF4:Yb/Er@NaGdF4 improved the upconversion luminescence (UCL) performance, and the designed delivery system could also be applied for simultaneous UCL and magnetic resonance (MR) imaging, which could be a good candidate as a dual-modal imaging nanoprobe. Therefore, we developed a multifunctional yolk–shell delivery system, which could have potential applications as a visualized theranostic nanoprobe to overcome MDR in breast cancer.
危险品化学品经营许可证（带存储）