Multicolor upconversion luminescence (UCL) plays an essential role in anti-fake and information encipher. Here, we report a strategy to expand the color-adjustable emission range by regulating the doping concentration of Yb3+ in core@shell (C@S) upconversion nanoparticles (UCNPs) under the excitation of near-infrared (NIR) light at 980 nm and promoting the energy-transfer process. Subsequently, multicolor UCNPs were combined with acrylamide hydrogel to construct a three-dimensional (3D) information code with an adjustable emission color. The encoded information is readable only under 980 nm excitation light and disappears as soon as the excitation light is removed. We adopted three strategies to improve the security: multiple permutations and combinations of different emission light hydrogel blocks, the combination of rich optical information and binary code, and the shape coding of hydrogel blocks. Constructing a complex and changeable coding library significantly guarantees that the data can be enciphered and deciphered by simple light irradiation, and the content can be edited by permutation and combination combined with information coding rules. Therefore, it is expected to provide ideas for developing intelligent anti-counterfeiting materials and devices.
Yinyin Chen,Xinying She,Zhouping Yang,Changfang Lu,Wei Zhang,Dongju Feng,Wei Wu,Xianxiang Wang
Doxorubicin hydrochloride (DOX), an anthraquinone-based antibiotic, is widely used in human tumors treatment. However, the residues of DOX in body would pose a threat to the health of heart and liver. Herein, a photochemical sensor NaYF 4 :Yb/Tm@NaYF 4 :Yb-Cit-CD (UCNPs) for detecting DOX has been developed in this paper. The fluorescence emission spectrum of UCNPs under 980 nm laser excitation has a wide range overlap with UV–vis absorption spectrum of DOX. Therefore, the fluorescence emission of UCNPs at 480 nm can be quenched by DOX. The UCNPs sensor has displayed a linear range of 0.05–20 μg/mL with a detection limit (LOD) of 0.005 μg/mL for DOX. Furthermore, the results of recovery for DOX in human serum samples is 98.68–104.20% and in accord with those obtained by HPLC and UV–vis.
Semiconductor photocatalysis is a promising strategy for wastewater treatment. However, a limited photoresponse range, rapid recombination of photoinduced charge carriers, poor stability, and other problems have posed obstacles to practical applications. Herein, a facile strategy to fabricate a near-infrared-driven broadband photocatalyst was developed by anchoring the core–shell nanostructure of NaYF4:Yb,Tm@NaYF4:Yb,Nd@TiO2 (Tm@Nd@TiO2) onto the surface of porous silica/carbon (mSC) electrospun fibers. The Tm@Nd@TiO2 nanoparticles (NPs) exhibited strong near-infrared light absorption and energy transfer from the NaYF4:Yb,Tm@NaYF4:Yb,Nd core to the TiO2 shell, triggering the photocatalytic reaction. In addition, the interconnected mesoporous structure and carbon network of Tm@Nd@TiO2/mSC was found to be beneficial in improving the adsorption capacity toward organic pollutants, promoting the separation of photogenerated carriers, and further improving the overall photocatalytic performance. The photocatalytic activity of Tm@Nd@TiO2/mSC nanocomposite was evaluated by degrading methyl orange solution in the visible-near-infrared and simulated sunlight regions. The Tm@Nd@TiO2/mSC nanocomposite exhibited excellent adsorption performance. The photocatalytic activity of Tm@Nd@TiO2/mSC was found to be 3 times higher than that of bare Tm@Nd@TiO2 over 60 min.
Luminescence thermometry has recently been gaining popularity in science and technology fields. However, most reported works have used the fluorescence intensity ratio (FIR) to obtain the temperature based on thermally coupled energy levels (TCLs), which have hindered the sensitivity of the technique and limited its applications. Here, NaYF4:Yb/Tm@NaYF4:Yb/Ho microcrystals were prepared using a hydrothermal method. Based on the non-thermally coupled energy levels (NTCLs) of the double luminescent ionic centers Tm3+ and Ho3+, the materials exhibited temperature-dependent luminescence in the range of 304 K to 574 K. The maximum sensitivities were found to be Sa = 0.135 K−1 at 574 K and Sr = 1.101% K−1 at 484 K based on red (Tm3+) and green (Ho3+) emission bands. This study has provided a promising new strategy to break the TCL restriction and has shown the material to have potential applications in luminescence thermometry.
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