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Quantum dots (QDs) have shown great potential to provide spatial, temporal, and structural information for biological systems. However, blinking, photobleaching, and spectral blueshift are adverse effects on their practical applications in biomedical research. An investigation of the effects of six reducing agents including cysteine (Cys), 1,4‐dithiothreitol (DTT), ethyl gallate (EG), L ‐glutathione (GSH), mercaptoacetic acid (MAA), and thiourea (TU) on the photostability of single QDs was studied. Our experiments demonstrate that both DTT and EG effectively inhibit blinking, photobleaching, and spectral blueshift. GSH molecules block blinking and photobleaching of QDs. The other reagents, Cys, MAA, and TU, only have the ability to counteract blinking. Possible explanations are given on the basis of research evidence. The results suggest possibilities for significant improvements in QDs for biological applications by adjusting the environmental conditions. 相似文献
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Auger Ionization Beats Photo‐Oxidation of Semiconductor Quantum Dots: Extended Stability of Single‐Molecule Photoluminescence 下载免费PDF全文
Shin‐ichi Yamashita Morihiko Hamada Prof. Shunsuke Nakanishi Hironobu Saito Prof. Yoshio Nosaka Dr. Shin‐ichi Wakida Dr. Vasudevanpillai Biju 《Angewandte Chemie (International ed. in English)》2015,54(13):3892-3896
Despite the bright and tuneable photoluminescence (PL) of semiconductor quantum dots (QDs), the PL instability induced by Auger recombination and oxidation poses a major challenge in single‐molecule applications of QDs. The incomplete information about Auger recombination and oxidation is an obstacle in the resolution of this challenge. Here, we report for the first time that Auger‐ionized QDs beat self‐sensitized oxidation and the non‐digitized PL intensity loss. Although high‐intensity photoactivation insistently induces PL blinking, the transient escape of QDs into the ultrafast Auger recombination cycle prevents generation of singlet oxygen (1O2) and preserves the PL intensity. By the detection of the NIR phosphorescence of 1O2 and evaluation of the photostability of single QDs in aerobic, anaerobic, and 1O2 scavenger‐enriched environments, we disclose relations of Auger ionization and 1O2‐mediated oxidation to the PL stability of single QDs, which will be useful during the formulation of QD‐based single‐molecule imaging tools and single‐photon devices. 相似文献
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Frontispiece: Auger Ionization Beats Photo‐Oxidation of Semiconductor Quantum Dots: Extended Stability of Single‐Molecule Photoluminescence 下载免费PDF全文
Shin‐ichi Yamashita Morihiko Hamada Prof. Shunsuke Nakanishi Hironobu Saito Prof. Yoshio Nosaka Dr. Shin‐ichi Wakida Dr. Vasudevanpillai Biju 《Angewandte Chemie (International ed. in English)》2015,54(13)
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Back Cover: Single‐Nanoparticle Cell Barcoding by Tunable FRET from Lanthanides to Quantum Dots (Angew. Chem. Int. Ed. 41/2018) 下载免费PDF全文
Chi Chen Dr. Lijiao Ao Yu‐Tang Wu Vjona Cifliku Dr. Marcelina Cardoso Dos Santos Emmanuel Bourrier Dr. Martina Delbianco Prof. David Parker Dr. Jurriaan M. Zwier Dr. Liang Huang Prof. Niko Hildebrandt 《Angewandte Chemie (International ed. in English)》2018,57(41):13692-13692
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Electron transfer (ET) kinetics of CdSe/ZnS core/shell quantum dots (QDs) on bare coverslips and a TiO2 nanoparticle‐coated thin film has been investigated at the single‐molecule level. The QDs prepared have three different diameters of 3.6, 4.6, and 6.4 nm. The trajectories of fluorescence intensity are acquired with respect to the arrival time. The on‐time events and subsequent fluorescence lifetimes are shorter with decreasing size. Given the lifetime measurements for QDs on glass and TiO2, the rate constant of ET from QDs to TiO2 may be determined to be 1.3×107, 6.0×106, and 4.7×106 s?1 for the increasing sizes of the QDs. The plot of on‐time probability density versus arrival time is characterized by power‐law statistics in the short time region and a bending tail in the long time region. Marcus’s ET model is employed to satisfactorily fit the bending tail behavior and to further calculate the ET rate constants. The theoretical counterparts for the different sizes are 1.4×107, 6.4×106, and 1.9×106 s?1, showing good agreement with the experimental results. 相似文献
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Inside Back Cover: Single‐Molecule Mechanochemical Sensing Using DNA Origami Nanostructures (Angew. Chem. Int. Ed. 31/2014) 下载免费PDF全文
Dr. Deepak Koirala Prakash Shrestha Tomoko Emura Kumi Hidaka Shankar Mandal Prof. Dr. Masayuki Endo Prof. Dr. Hiroshi Sugiyama Prof. Dr. Hanbin Mao 《Angewandte Chemie (International ed. in English)》2014,53(31):8251-8251