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1.
In this article, we describe the analysis of aptamers for Hg2+ ions through CE with LIF (CE‐LIF) detection using 2% poly(ethylene oxide) solutions containing OliGreen (fluorophore). In the presence of an EOF, DNA strands migrating against the EOF were detected at the cathode end. Four DNA strands – T33, T5C28, T5C5T23, and T15C5T13 – could not be separated through CE‐LIF in the absence of Hg2+. At 0.3 mM Hg2+, however, all four were partially separated within 20 min, with SDs of the migration times all being less than 2.5%. From the CE, fluorescence, and ellipticity data, we concluded that the conformations of these four DNA strands all changed from random‐coil to folded structures as a result of T–Hg2+–T bonding. In addition, we found that this CE approach provided different electropherograms patterns for T7, T15, and T33 in the absence and presence of Hg2+, indicating various interactions of the DNA strands with Hg2+. Using this simple, high‐resolution CE approach, we also demonstrated that adenosine triphosphate has a stronger interaction with the adenosine triphosphate aptamer than with either the platelet‐derived growth factor aptamer or T33. This CE approach holds great potential for screening aptamers for small solutes, studying the catalytic activity of DNAzymes, and evaluating the biological functions of microRNA. 相似文献
2.
The Relationship between DNA Sequences and Oligonucleotide‐Templated Silver Nanoclusters and Their Fluorescence Properties
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Ye Teng Xuan Yang Lei Han Prof. Erkang Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(4):1111-1115
A novel approach was developed to study the relationship between DNA sequences and DNA‐templated silver nanoclusters (DNA‐Ag NCs) in detail by using an ordinary DNA strand as an example. Three kinds of Ag NCs are formed by using the DNA strand as a scaffold. By dividing the DNA template into several parts according to their different affinities to Ag+, it was found that the fluorescence properties of DNA‐Ag NCs are related to not only the sequences but also to the position of different parts in the template, which provides a more efficient approach to obtain DNA‐Ag NCs with required photoluminescence properties and may ultimately contribute to the targeted synthesis of DNA‐Ag NCs. 相似文献
3.
Rui-Zhi Wang Dan-Ling Zhou Hong Huang Ming Zhang Jiu-Ju Feng Ai-Jun Wang 《Mikrochimica acta》2013,180(13-14):1287-1293
Water–soluble fluorescent silver nanoclusters (Ag NCs) were prepared with the assistance of commercially available polyinosinic acid (PI) or polycytidylic acid (PC). The fluorescence of the Ag NCs is effectively quenched by trace mercury(II) ions, which can be applied for their detection. The response of the Ag NCs prepared with PI to Hg(II) ion is linear in the Hg(II) concentration range from 0.05 to 1.0 μM (R2?=?0.9873), and from 0.5 to 10 μM of Hg(II) (R2?=?0.9971) for Ag NCs prepared with PC. The detection limits are 3.0 nM and 9.0 nM (at an S/N of 3), respectively. The method is simple, sensitive and fairly selective. Figure
Water-soluble fluorescent Ag nanoclusters (NCs) were facilely prepared using commercially available polyinosinic acid or polycytidylic acid. The fluorescence intensity of the as-prepared Ag NCs was effectively quenched by trace Hg2+, which was used for the detection of Hg2+ in water samples with good performance. 相似文献
4.
Cheng-Kang Chiang Yang-Wei Lin Cho-Chun Hu Huan-Tsung Chang 《Journal of the American Society for Mass Spectrometry》2009,20(10):1834-1840
We have used electrospray ionization mass spectrometry (ESI-MS) and fluorescence and circular dichroism (CD) spectroscopy
to explore the binding of ethidium bromide (EthBr) to non-self-complementary polythymine (polyT) strands in the absence and
presence of Hg2+ ions. In the gas phase, ESI-MS revealed that Hg2+ ions have greater affinity, through T-Hg2+-T coordination, toward polyT strands than do other metal ions. These findings are consistent with our fluorescence and CD
results obtained in solution; they revealed that more T33-EthBr-Hg2+ complexes existed upon increasing the concentrations of Hg2+ ions (from 0 to 50 μM). Surprisingly, the ESI-MS data indicated that the Hg2+ concentration dependence of the interaction between T33 and EthBr is biphasic. Our ESI-MS data revealed that the T33-EthBr-Hg2+ complexes formed with various stoichiometries depending on their relative concentrations of the components and the length
of the DNA strand. When the concentrations of T33/EthBr/Hg2+ were 5/5/2. 5 μM and 5/10/7. 5 μM, 1:1:1 and 1:1:2 T33-EthBr-Hg2+ complexes were predominantly formed, respectively. Thus, Hg2+-induced DNA conformational changes clearly affect the interactions between DNA and EthBr. 相似文献
5.
Dr. Chuanxi Wang Lin Xu Yu Wang Dan Zhang Prof. Xiaodong Shi Fengxia Dong Prof. Kui Yu Prof. Quan Lin Prof. Bai Yang 《化学:亚洲杂志》2012,7(7):1652-1656
Facile preparation of water‐soluble and fluorescent Ag nanoclusters (NCs) stabilized by glutathione at room temperature is described. Although the glutathione layer was introduced to prevent the silver nanoparticles from decomposition and increase their water solubility, this simple surface optimization resulted in surprisingly high efficiency of selective Hg2+ sensing, where the limit of detection (LOD) was as low as 10?10 M (0.02 ppb, 0.1 nM ). This result revealed a simple and practical strategy for Hg2+ detection using fluorescent Ag NCs as sensor probe, with the lowest detecting limits reported to date. 相似文献
6.
In this study, we have developed a label-free, dual functional detection strategy for highly selective and sensitive determination of aqueous Ag+ and Hg2+ by using cytidine stabilized Au NCs and AuAg NCs as fluorescent turn-on and turn off probes, respectively. The Au NCs and AuAg NCs showed a remarkably rapid response and high selectivity for Ag+ and Hg2+ over other metal ions, and relevant detection limit of Ag+ and Hg2+ is ca. 10 nM and 30 nM, respectively. Importantly, the fluorescence enhanced Au NCs by doping Ag+ can be conveniently reusable for the detection of Hg2+ based on the corresponding fluorescence quenching. The sensing mechanism was based on the high-affinity metallophilic Hg2+–Ag+ interaction, which effectively quenched the fluorescence of AuAg NCs. Furthermore, these fluorescent nanoprobes could be readily applied to Ag+ and Hg2+ detection in environmental water samples, indicating their possibility to be utilized as a convenient, dual functional, rapid response, and label-free fluorescence sensor for related environmental and health monitoring. 相似文献
7.
Xiaofang Jia Jing Li Prof. Erkang Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(42):13494-13500
This work describes a novel strategy for the highly sensitive and selective detection of cysteine (Cys) and glutathione (GSH) based on the Hg2+–AGRO100–malachite green (MG) complex system. The dye MG, which has a very low quantum yield in aqueous solution by itself, can bind with the thymine‐rich DNA AGRO100 in the presence of Hg2+ ions to generate a striking fluorescence intensity enhancement of 1000‐fold. As sulfur‐containing amino acids, Cys and GSH effectively sequester Hg2+ ions from the Hg2+–AGRO100–MG complex structure to switch the ‘lit‐up’ chemosensor to the ‘off’ state (about a 50‐fold fluorescence intensity decrease), thus providing a facile, but effective, method to probe for Cys/GSH. The fluorescence titration, UV absorption, CD, and Raman spectra provide some insight into the structural and chemical basis for the enhancement effect. The formation of the Hg2+–AGRO100–MG complex significantly affects the electronic structure and conformation of the MG molecule by leading to an extended π system, which is the likely origin of the observed striking fluorescence intensity enhancement. Notably, the proposed sensing platform exhibits exquisite selectivity and sensitivity toward Cys/GSH with limits of detection of 5 nM for Cys and 10 nM for GSH, respectively. Furthermore, the straightforward assay design avoids labeling of the probe, uses only commercially available materials, and still displays comparable sensitivity and excellent selectivity. 相似文献
8.
Metal-mediated base pairs by the interaction between metal ions and artificial bases in oligonucleotides has been widely used in DNA nanotechnology and biosensing technique. Using isothermal titration calorimetry, circular dichroism spectroscopy and fluorescence spectroscopy, the folding process of T-C-rich oligonucleotides (TCO) induced by Hg2+ and Ag+ with the synthetic sequence d(T6C6T6C6T6C6T6) was studied and analyzed. Although thermodynamic data predict that TCO should initially fold into a relatively stable hairpin through two possible pathways of conformational transitions whether Hg2+ or Ag+ were added at first, the mechanisms and final products between the two are entirely different from isothermal titration calorimetry outcomes. When Hg2+ were added first, the haipin was formed through T-Hg-T structure with further stabilization by C-Ag-C after Ag+ addition. However, it is proposed that an unusual metal-base pair for Ag+ binding is generated instead classical C-Ag-C when Ag+ was injected first. Moreover, further confirmation of this unconventional metal-base pair T-Ag-C was verified by circular dichroism and fluorescence spectroscopy. 相似文献
9.
We demonstrate the utilization of silver/gold nanocages (Ag/Au NCs) deposited onto transparent indium tin oxide (ITO) film glass as the basis of a reagentless, simple and inexpensive mercury probe. The localized surface plasmon resonance (LSPR) peak wavelength was located at ∼800 nm. By utilizing the redox reaction between Hg2+ ions and Ag atoms that existed in Ag/Au NCs, the LSPR peak of Ag/Au NCs was blue-shifted. Thus, we develop an optical sensing probe for the detection of Hg2+ ions. The LSPR peak changes were lineally proportional to the concentration of Hg2+ ions over the range from 10 ppb to 0.5 ppm. The detection limit was ∼5 ppb. This plasmonic probe shows good selectivity and high sensitivity. The proposed optical probe is successfully applied to the sensing of Hg2+ in real samples. 相似文献
10.
A Terbium Metal–Organic Framework for Highly Selective and Sensitive Luminescence Sensing of Hg2+ Ions in Aqueous Solution
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Dr. Tifeng Xia Dr. Tao Song Gege Zhang Prof. Dr. Yuanjing Cui Dr. Yu Yang Prof. Dr. Zhiyu Wang Prof. Dr. Guodong Qian 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(51):18429-18434
A series of isomorphic lanthanide metal–organic frameworks (MOFs) Ln(TATAB)?(DMF)4(H2O)(MeOH)0.5 (LnTATAB, Ln=Eu, Tb, Sm, Dy, Gd; H3TATAB=4,4′,4′′‐s‐triazine‐1,3,5‐triyltri‐p‐aminobenzoic acid) have been solvothermally synthesized and structurally characterized. Among these MOFs, TbTATAB exhibits good water stability and a high fluorescence quantum yield. Because mercury ions (Hg2+) have a high affinity to nitrogen atoms, and the space between multiple nitrogen atoms from triazine and imino groups is suitable for interacting with Hg2+ ions, TbTATAB shows highly selective and sensitive detection of Hg2+ in aqueous solution with a detection limit of 4.4 nm . Furthermore, it was successfully applied to detect Hg2+ ions in natural water samples. 相似文献
11.
Xiaobo Huang Jie Meng Yu Dong Yixiang Cheng Chengjian Zhu 《Journal of polymer science. Part A, Polymer chemistry》2010,48(5):997-1006
Three chiral polymers P‐1 , P‐2 , and P‐3 could be obtained by the polymerization of (R)‐6,6′‐dibutyl‐3,3′‐diiodo‐2, 2′‐binaphthol (R‐M‐1) , (R)‐6,6′‐dibutyl‐3,3′‐diiodo‐2,2′‐bisoctoxy‐1,1′‐binaphthyl ( R‐M‐2 ), and (R)‐6,6′‐dibutyl‐3,3′‐diiodo‐2,2′‐bis (diethylaminoethoxy)‐1,1′‐binaphthyl ( R‐M‐3 ) with 4,7‐diethynyl‐benzo[2,1,3]‐thiadiazole ( M‐1) via Pd‐catalyzed Sonogashira reaction, respectively. P‐1 , P‐2 , and P‐3 can show pale red, blue–green, and orange fluorescence. The responsive optical properties of these polymers on various metal ions were investigated by fluorescence spectra. Compared with other cations, such as Co2+, Ni2+, Ag+, Cd2+, Cu2+, and Zn2+, Hg2+ can exhibit the most pronounced fluorescence response of these polymers. P‐1 and P‐2 show obvious fluorescence quenching effect upon addition of Hg2+, on the contrary, P‐3 shows fluorescence enhancement. Three polymer‐based fluorescent sensors also show excellent fluorescence response for Hg2+ detection without interference from other metal ions. The results indicate that these kinds of tunable chiral polybinaphthyls can be used as fluorescence sensors for Hg2+ detection. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 997–1006, 2010 相似文献
12.
Cecilia Cerretani Hiroki Kanazawa Tom Vosch Jiro Kondo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(48):17313-17317
DNA has been used as a scaffold to stabilize small, atomically monodisperse silver nanoclusters, which have attracted attention due to their intriguing photophysical properties. Herein, we describe the X‐ray crystal structure of a DNA‐encapsulated, near‐infrared emitting Ag16 nanocluster (DNA–Ag16NC). The asymmetric unit of the crystal contains two DNA–Ag16NCs and the crystal packing between the DNA–Ag16NCs is promoted by several interactions, such as two silver‐mediated base pairs between 3′‐terminal adenines, two phosphate–Ca2+–phosphate interactions, and π‐stacking between two neighboring thymines. Each Ag16NC is confined by two DNA decamers that take on a horse‐shoe‐like conformation and is almost fully shielded from the solvent environment. This structural insight will aid in the determination of the structure/photophysical property relationship for this class of emitters and opens up new research opportunities in fluorescence imaging and sensing using noble‐metal clusters. 相似文献
13.
Jiang Zhiliang Zhang Jing Wen Guiqing Liang Aihui Liu Qingye Kang Caiyan He Xingcun 《中国化学》2010,28(7):1159-1164
The AuRe nanoalloy particles in molar ratio of 9:1 were prepared by sodium borohydride procedure, and modified by single strand DNA (ssDNA) to prepare an aptamer AuRe nanoprobe (AuRessDNA) for Hg2+. In the pH 7.0 Na2HPO4‐NaH2PO4 buffer solution and in the presence of NaCl, Hg2+ interacted with AuRessDNA to form double‐stranded T‐Hg2+‐T mismatched and release AuRe nanoparticles that aggregate to large AuRe nanoparticles clusters causing the resonance scattering (RS) peak red shifting and the RS intensity enhanced linearly. On those grounds, 0.067–33.3 nmol·L?1 Hg2+ can be detected rapidly by the aptamer‐modified AuRe nanoparticles RS assay, with a detection limit of 0.04 nmol·L?1 Hg2+. If the aggregated AuRe particles were removed by membrane filtration, the excess AuRessDNA in the filtration solution exhibits catalytic effect on the new Te particle reaction between Na2TeO4 and SnCl2. As the concentration of Hg2+ increased, the AuRessDNA nanoparticles in the filtrate solution decreased, the RS intensity at 734 nm decreased linearly. The Hg2+ concentration (c) in the range of 0.00133–0.267 nmol·L?1 was linear to the decreased RS intensity (ΔI734nm), with a regression equation of ΔI= ?786.4c?4.4, a correlation coefficient of 0.9975, and a detection limit of 0.9 pmol·L?1 Hg2+. This method was applied to the detection of Hg2+ in water samples, with satisfactory results. 相似文献
14.
In this paper, a novel colorimetric biosensor for Hg2+ and DNA molecules is presented based on Hg2+ stimulated oxidase-like activity of bovine serum albumin protected silver clusters (BSA-Ag NCs). Under mild conditions, Hg2+ activated BSA-Ag NCs to show high catalytic activity toward the oxidation of 3,3′,5, 5′-tetramethylbenzidine (TMB) using ambient dissolved oxygen as an oxidant. The oxidase-like activity of BSA-Ag NCs was “switched-on” selectively in the presence of Hg2+, which permitted a novel and facile colorimetric sensor for Hg2+. As low as 25 nmol L−1 Hg2+ could be detected with a linear range from 80 nmol L−1 to 50 mmol L−1. In addition, the sensing strategy was also employed to detect DNA molecules. Hg2+ is known to bind very strongly and specifically with two DNA thymine bases (T) to form thymine–Hg2+–thymine (T–Hg2+–T) base pairs. The hairpin-structure was disrupted and Hg2+ ions were released after hybridization with the DNA target. By coupling the Hg2+ switched-on the oxidase-mimicking activity of BSA-Ag NCs, we developed a novel label-free strategy for facile and fast colorimetric detection of DNA molecules. More important, target DNA can be detected as low as 10 nmol L−1 with a linear range from 30 to 225 nmol L−1. Compared with other methods, this method presents several advantages such as the independence of hydrogen peroxide, high sensitivity and good selectivity, avoiding any modification or immobilization of DNA, which holds a great potential of metal NCs for clinical application in biosensing and biotechnology. 相似文献
15.
Ying Liu Ximing Rong Mingze Li Maxim S. Molokeev Jing Zhao Zhiguo Xia 《Angewandte Chemie (International ed. in English)》2020,59(28):11634-11640
The incorporation of impurity ions or doping is a promising method for controlling the electronic and optical properties and the structural stability of halide perovskite nanocrystals (NCs). Herein, we establish relationships between rare‐earth ions doping and intrinsic emission of lead‐free double perovskite Cs2AgInCl6 NCs to impart and tune the optical performances in the visible light region. Tb3+ ions were incorporated into Cs2AgInCl6 NCs and occupied In3+ sites as verified by both crystallographic analyses and first‐principles calculations. Trace amounts of Bi doping endowed the characteristic emission (5D4→7F6‐3) of Tb3+ ions with a new excitation peak at 368 nm rather than the single characteristic excitation at 290 nm of Tb3+. By controlling Tb3+ ions concentration, the emission colors of Bi‐doped Cs2Ag(In1?xTbx)Cl6 NCs could be continuously tuned from green to orange, through the efficient energy‐transfer channel from self‐trapped excitons to Tb3+ ions. Our study provides the salient features of the material design of lead‐free perovskite NCs and to expand their luminescence applications. 相似文献
16.
Yong Tian Wei Shi Jianmin Luo Fudong Ma Hongyu Mi Yanli Lei 《Journal of polymer science. Part A, Polymer chemistry》2013,51(17):3636-3645
A type of fluorescent–magnetic dual‐function nanocomposite, Fe3O4@SiO2@P‐2, was successfully obtained by Cu+‐catalyzed click reaction between acetylene (C?C? H)‐substituted carbazole‐based conjugated polymer ( P‐2) and azide‐terminated silica‐coated magnetic iron oxide nanoparticles (Fe3O4@SiO2–N3). Optical and magnetization analyses indicate that Fe3O4@SiO2@P‐2 exhibits stable fluorescence and rapid magnetic response. The fluorescence of Fe3O4@SiO2@P‐2 was quenched significantly in the presence of I? and gave a detection limit (DL) of ~8.85 × 10?7 M. Given the high binding constant and matching ratio between Hg2+ and I?, the fluorescence of Fe3O4@SiO2@P‐2/I? complex recovered efficiently with the addition of Hg2+. A DL of ~4.17 × 10?7 M was obtained by this probing system. Recycling of Fe3O4@SiO2@P‐2 probe was readily achieved by simple magnetic separation. Results indicate that Fe3O4@SiO2@P‐2 can be used as an “on–off–on” fluorescent switchable and recyclable Hg2+ probe. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3636–3645 相似文献
17.
Bin Yang Feng Hong Junsheng Chen Yuxuan Tang Li Yang Youbao Sang Xusheng Xia Jingwei Guo Haixiang He Songqiu Yang Weiqiao Deng Keli Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(8):2300-2305
A series of lead‐free double perovskite nanocrystals (NCs) Cs2AgSb1?yBiyX6 (X: Br, Cl; 0≤y≤1) is synthesized. In particular, the Cs2AgSbBr6 NCs is a new double perovskite material that has not been reported for the bulk form. Mixed Ag–Sb/Bi NCs exhibit enhanced stability in colloidal solution compared to Ag–Bi or Ag–Sb NCs. Femtosecond transient absorption studies indicate the presence of two prominent fast trapping processes in the charge‐carrier relaxation. The two fast trapping processes are dominated by intrinsic self‐trapping (ca. 1–2 ps) arising from giant exciton–phonon coupling and surface‐defect trapping (ca. 50–100 ps). Slow hot‐carrier relaxation is observed at high pump fluence, and the possible mechanisms for the slow hot‐carrier relaxation are also discussed. 相似文献
18.
We have developed a fluorescence technique for the detection of Hg2+ and Pb2+ ions using polythymine (T33)/benzothiazolium-4-quinolinium dimer derivative (TOTO-3) and polyguanine (G33)/terbium ions (Tb3+) conjugates, respectively. Hg2+ ions induce T33 to form folded structures, leading to increased fluorescence of the T33/TOTO-3 conjugates. Because Pb2+ ions compete with Tb3+ ions to form complexes with G33, the extent of formation of the G33-Tb3+ complexes decreases upon increasing the Pb2+ concentration, leading to decreased fluorescence at 545 nm when excited at 290 nm. To minimize interference from Hg2+ ions during the detection of Pb2+ ions, we conducted two-step fluorescence measurements; prior to addition of the G33/Tb3+ probe, we recorded the fluorescence of a mixture of the T33/TOTO-3 conjugates and Hg2+ ions. The fluorescence signal obtained was linear with respect to the Hg2+ concentration over the range 25.0-500 nM (R2 = 0.99); for Pb2+ ions, it was linear over the range 3.0-50 nM (R2 = 0.98). The limits of detection (at a signal-to-noise ratio of 3) for Hg2+ and Pb2+ ions were 10.0 and 1.0 nM, respectively. Relative to other techniques for the detection of Hg2+ and Pb2+ ions in soil and water samples, our present approach is simpler, faster, and more cost-effective. 相似文献
19.
By using a copper‐promoted alkyne–azide cycloaddition reaction, two boron dipyrromethene (BODIPY) derivatives bearing a bis(1,2,3‐triazole)amino receptor at the meso position were prepared and characterized. For the analogue with two terminal triethylene glycol chains, the fluorescence emission at 509 nm responded selectively toward Hg2+ ions, which greatly increased the fluorescence quantum yield from 0.003 to 0.25 as a result of inhibition of the photoinduced electron transfer (PET) process. By introducing two additional rhodamine moieties at the termini, the resulting conjugate could also detect Hg2+ ions in a highly selective manner. Upon excitation at the BODIPY core, the fluorescence emission of rhodamine at 580 nm was observed and the intensity increased substantially upon addition of Hg2+ ions due to inhibition of the PET process followed by highly efficient fluorescence resonance energy transfer (FRET) from the BODIPY core to the rhodamine moieties. The Hg2+‐responsive fluorescence change of these two probes could be easily seen with the naked eye. The binding stoichiometry between the probes and Hg2+ ions in CH3CN was determined to be 1:2 by Job′s plot analysis and 1H NMR titration, and the binding constants were found to be (1.2±0.1)×1011 m ?2 and (1.3±0.3)×1010 m ?2, respectively. The overall results suggest that these two BODIPY derivatives can serve as highly selective fluorescent probes for Hg2+ ions. The rhodamine derivative makes use of a combined PET‐FRET sensing mechanism which can greatly increase the sensitivity of detection. 相似文献
20.
Bin Yang Feng Hong Junsheng Chen Yuxuan Tang Li Yang Youbao Sang Xusheng Xia Jingwei Guo Haixiang He Songqiu Yang Weiqiao Deng Keli Han 《Angewandte Chemie (International ed. in English)》2019,58(8):2278-2283
A series of lead‐free double perovskite nanocrystals (NCs) Cs2AgSb1?yBiyX6 (X: Br, Cl; 0≤y≤1) is synthesized. In particular, the Cs2AgSbBr6 NCs is a new double perovskite material that has not been reported for the bulk form. Mixed Ag–Sb/Bi NCs exhibit enhanced stability in colloidal solution compared to Ag–Bi or Ag–Sb NCs. Femtosecond transient absorption studies indicate the presence of two prominent fast trapping processes in the charge‐carrier relaxation. The two fast trapping processes are dominated by intrinsic self‐trapping (ca. 1–2 ps) arising from giant exciton–phonon coupling and surface‐defect trapping (ca. 50–100 ps). Slow hot‐carrier relaxation is observed at high pump fluence, and the possible mechanisms for the slow hot‐carrier relaxation are also discussed. 相似文献