Non-rare earth ion-activated Yb 3+ -rich fluoride matrix luminescent materials exhibit higher absorption efficiency under near-infrared (NIR) laser excitation, and are more suitable for upconversion (UC) photoluminescence and optical heating applications. These materials are highly promising fluorescent self-labeling nano-heaters. In this work, Bi 3+ -codoped β-NaYbF 4 :Tm 3+ UC nanomaterials were synthesized by combining the hydrothermal reaction with the molten salt method. The effects of Bi 3+ doping on the crystalline phase composition, micromorphology, upconversion luminescence (UCL) properties, spectral characteristics , and optical heating performance of the synthesized materials were investigated in detail. The co-doping of 5–20 mol% Bi 3+ was found to significantly enhance the near-infrared (NIR) UCL intensity of NaYbF 4 : Tm 3+ . In particular, t he sample doped with 15 mol% Bi 3+ emitted nearly pure 801 nm monochromatic near-infrared light under 980 nm optical excitation , and its I NIR /I Blue ratio increased dramatically from 0.97 without Bi 3+ doping to 1599. This material exhibited efficient photothermal conversion capability, and the center temperature of the sample can reach ∼147.6 °C under 10 s laser irradiation, achieving a high photothermal conversion efficiency of 129.53 °C W −1 , together with excellent photothermal conversion stability. The mechanism behind the enhanced NIR emission of Bi 3+ -doped nanomaterials was also elucidated based on the energy level transition strategy.
As a new type of optical imaging, fluorescence molecular tomography (FMT) has great potential in the field of biomedicine. However, current fluorescent probes still have some limitations that make in vivo FMT imaging quite challenging. In this study, Cit-NaYb0.98−xF4:2%Tm3+/x%Sr2+ upconversion nanoparticles (UCNPs) were successfully prepared by a one-step hydrothermal method, which overcomes the shortcomings of most organic small molecular fluorescent dyes. Importantly, Sr2+ doping can not only significantly reduce the radius of NaYbF4 but also considerably enhance the 800 ± 10 nm emission by about 35.5 times. CCK-8 assay and confocal laser scanning microscopy images (CLSM) also showed that the toxicity of NaYb0.93F4:2%Tm3+/5%Sr2+ to HeLa cells was decreased due to size reduction. In vitro and in vivo experiments showed that the UCNPs have excellent FMT imaging quality. After using the Compressive Sampling Matching Pursuit (CoSaMP) algorithm for 3D reconstruction, the location error of the fluorophore center was small, and the reconstructed target shape was close to that of the real light source. The reconstruction results further proved the feasibility and efficiency of Cit-NaYbF4:2%Tm3+/x%Sr2+ UCNPs for in vivo FMT imaging. This kind of UCNPs has been applied to FMT imaging and 3D reconstruction in vivo for the first time, promoting the development of FMT technology.
Fabrication of broad-spectrum response photocatalysts in a controllable manner that can efficiently utilize solar light as much as possible remains a top priority target yet a challenging task. In this work, a facile approach of synchronous bottom-up growth was employed to construct UCNP/NMIL(Ti) nanohybrids via NH 2 -BDC (NH 2 -MIL-125-ligand) linkage between upconversion NaYbF 4 :Tm 3+ nanoparticles (~13-nm) and NH 2 -MIL-125. The ligand sharing integration strategy generated abundant oxygen vacancies and coordinatively-unsaturated-metal sites, efficiently enhanced light absorption, energy-transfer upconversion (UC-PL), photo-induced e - / h + generation, and their separation (CV, EIS, Photocurrent-density). Consequently, UCNP/NMIL(Ti) exhibited excellent acetaldehyde photodegradation activity, with 12.5–77.0-folds higher rate constants ( k a ) than those of state-of-the-art photocatalysts under visible light and high humidity. Furthermore, the photocatalytic activity of UCNP/NMIL(Ti) only declined from 96.0% to 92.5% after five cycling-runs, demonstrating its remarkable photo-catalytic stability. Considering these attributes, the current strategy provides an avenue to synthesize efficient UCNPs/MOF composites for widespread usage in a variety of commercial applications.
危险品化学品经营许可证（带存储）