The doping concentration of lanthanide ions is important for manipulating the luminescence properties of upconversion nanoparticles （UCNPs）. However, the serious concentration quenching in highly doped UCNPs remains...The doping concentration of lanthanide ions is important for manipulating the luminescence properties of upconversion nanoparticles （UCNPs）. However, the serious concentration quenching in highly doped UCNPs remains a vital restriction for further enhanced upconversion luminescence （UCL）. Herein, we examined the effect of temperature on the concentration quenching of rare-earth UCNPs, an issue that has been overlooked, and we show that it is significant for biomedical or optical applications of UCNPs. In this work, we prepared a series of UCNPs by doping Er3. luminescent centers at different concentrations in a NaLuF4：Yb3＋ matrix. At room temperature （298 K）, steady-state photoluminescence （PL） spectroscopy showed substantial concentration quenching of the Er~ emission with increasing doping concentrations. However, the concentration quenching effect was no longer effective at lower temperatures. Kinetic curves obtained from time-resolved PL spectroscopy further showed that the concen- tration quenching dynamics were vitally altered in the cryogenic temperature region, i.e., below 160 K. Our work on the temperature-switchable concentration quenching mechanism may shed light on improving UCL properties, promoting their practical applications.展开更多
Telomeres are protein-DNA complexes at the terminals of linear chromosomes, which protect chromoso-mal integrity and maintain cellular replicative capacity. From single-cell organisms to advanced animals and plants, s...Telomeres are protein-DNA complexes at the terminals of linear chromosomes, which protect chromoso-mal integrity and maintain cellular replicative capacity. From single-cell organisms to advanced animals and plants, structures and functions of telomeres are both very conser-vative. In cells of human and vertebral animals, telomeric DNA base sequences all are (TTAGGG)n. In the present work, we have obtained absorption and fluorescence spectra measured from seven synthesized oligonucleotides to simu-late the telomeric DNA system and calculated their relative fluorescence quantum yields on which not only telomeric DNA characteristics are predicted but also possibly the shortened telomeric sequences during cell division are im-plied. Oligonucleotide 5’- TTAGGGTTAGGG holds a low relative fluorescence quantum yield and remarkable excitation energy innerconversion, which tallies with the telomeric sequence of (TTAGGG)n. This result shows that telomeric DNA has a strong non-radiative or innerconvertible capabil-展开更多
基金This work was supported by the National Natural Science Foundation of China （Nos. 21373268, 21301121, and 21227803）, the open funding of Renmin University of China （Nos. 15XNLQ04 and 10XNI007）, and the open funding of the State Key Laboratory on Integrated Optoelectronics of Jilin University （No. IOSKL2015KF33）.
文摘The doping concentration of lanthanide ions is important for manipulating the luminescence properties of upconversion nanoparticles （UCNPs）. However, the serious concentration quenching in highly doped UCNPs remains a vital restriction for further enhanced upconversion luminescence （UCL）. Herein, we examined the effect of temperature on the concentration quenching of rare-earth UCNPs, an issue that has been overlooked, and we show that it is significant for biomedical or optical applications of UCNPs. In this work, we prepared a series of UCNPs by doping Er3. luminescent centers at different concentrations in a NaLuF4：Yb3＋ matrix. At room temperature （298 K）, steady-state photoluminescence （PL） spectroscopy showed substantial concentration quenching of the Er~ emission with increasing doping concentrations. However, the concentration quenching effect was no longer effective at lower temperatures. Kinetic curves obtained from time-resolved PL spectroscopy further showed that the concen- tration quenching dynamics were vitally altered in the cryogenic temperature region, i.e., below 160 K. Our work on the temperature-switchable concentration quenching mechanism may shed light on improving UCL properties, promoting their practical applications.
基金Thiswork was supported by the Science Creative Project of the Chinese Academy of Sciences (Grant No. KJCX2-H2).
文摘Telomeres are protein-DNA complexes at the terminals of linear chromosomes, which protect chromoso-mal integrity and maintain cellular replicative capacity. From single-cell organisms to advanced animals and plants, structures and functions of telomeres are both very conser-vative. In cells of human and vertebral animals, telomeric DNA base sequences all are (TTAGGG)n. In the present work, we have obtained absorption and fluorescence spectra measured from seven synthesized oligonucleotides to simu-late the telomeric DNA system and calculated their relative fluorescence quantum yields on which not only telomeric DNA characteristics are predicted but also possibly the shortened telomeric sequences during cell division are im-plied. Oligonucleotide 5’- TTAGGGTTAGGG holds a low relative fluorescence quantum yield and remarkable excitation energy innerconversion, which tallies with the telomeric sequence of (TTAGGG)n. This result shows that telomeric DNA has a strong non-radiative or innerconvertible capabil-
