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Highly Photoluminescent and Stable N-Doped Carbon Dots as Nanoprobes for Hg2+ Detection
摘要： We developed a microreactor with porous copper fibers for synthesizing nitrogen-doped carbon dots (N-CDs) with a high stability and photoluminescence (PL) quantum yield (QY). By optimizing synthesis conditions, including the reaction temperature, flow rate, ethylenediamine dosage, and porosity of copper fibers, the N-CDs with a high PL QY of 73% were achieved. The PL QY of N-CDs was two times higher with copper fibers than without. The interrelations between the copper fibers with different porosities and the N-CDs were investigated using X-ray photoelectron spectroscopy (XPS) and Fourier Transform infrared spectroscopy (FTIR). The results demonstrate that the elemental contents and surface functional groups of N-CDs are significantly influenced by the porosity of copper fibers. The N-CDs can be used to effectively and selectively detect Hg2+ ions with a good linear response in the 0~50 μM Hg2+ ions concentration range, and the lowest limit of detection (LOD) is 2.54 nM, suggesting that the N-CDs have great potential for applications in the fields of environmental and hazard detection. Further studies reveal that the different d orbital energy levels of Hg2+ compared to those of other metal ions can affect the efficiency of electron transfer and thereby result in their different response in fluorescence quenching towards N-CDs.
关键词： carbon dots,microreactor,Hg2+ detection,porous copper fibers
更新于2025-11-19 16:46:39
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A Phosphonate Substituted Ruthenium(II) Bipyridyl Derivative as Photoelectrochemical Probe for Sensitive and Selective Detection of Mercury(II) in Biofluids
摘要： A ruthenium(II) bipyridyl derivative photoelectrochemical probe, Ru-1, is synthesized and coupled with TiO2 nanoparticles (Ru-1/TiO2) for the specific recognition and highly sensitive PEC detection of Hg2+ in a series of biofluids. The probe is designed with a chromophore, a thiocyanate recognition unit, a π-conjugated photoelectron transfer pathway, and a phosphonate anchor. TiO2 nanoparticles with strong affinity to phosphonate and suitable conduction band energy are used as intermediate layers to increase the Ru-1 adsorption amount and amplify the photocurrent response. Under irradiation, the Ru-1/TiO2/FTO with strong visible light harvesting capacity, aqueous stability and efficient photoelectron transfer, shows a high and stable photocurrent response. In the presence of Hg2+, however, the specific Hg2+ and NCS coordination changes the photophysical properties of Ru-1, imposing the probe with a wider band gap, a weaker absorbance, and a poorer photoelectron and hole separation efficiency, thus resulting in a significant photocurrent decrease. Based on the Hg2+ induced photocurrent change, the Ru-1/TiO2/FTO shows good selectivity and high sensitivity towards the PEC detection of Hg2+, with wide linear ranges from 10-12 to 10-7 and 10-7 to 10-3 g/mL, and a low limit of detection of 0.63 pg/mL. The PEC probe is recyclable and accurate for selective detection of Hg2+ in urine, serum and cell extracts. The whole analysis can be completed within 15 minutes. These good analytical performances indicate the PEC method might have great potential for the onsite detection of small molecules in bio-systems.
关键词： Hg2+ detection,photoelectrochemical probe,TiO2 nanoparticles,ruthenium(II) bipyridyl derivative,biofluids
更新于2025-09-23 15:21:21
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Inkjet-printed phosphorescent Iridium(III) complex based paper sensor for highly selective detection of Hg2+
摘要： First of its kind inkjet-printed phosphorescent Iridium(III) complex [Ir(TPQ)2(4-EO2-pic)] paper based chemosensor has been developed for Hg2+ ions. The probe is highly selective towards mercury analyte over other metal ions (Cu2+, Ca2+, Co2+, Cd2+, Pb2+, Zn2+, Ni2+, Mg2+, Mn2+, Al3+, Fe3+, La3+, Ag+, K+, Na+ and Li+). [Ir(TPQ)2(4-EO2-pic)] complex solution gave a visible color change from orange to yellow and significant phosphorescence quenching. Upon addition of aqueous Hg2+, the [Ir(TPQ)2(4-EO2-pic)] inkjet-printed paper gave a significant color change in both normal and UV light. The detection limit was found out as 1.78 × 10-8 M. Cyclic voltammetry (CV) studies were conducted to explore the further utility of [Ir(TPQ)2(4-EO2-pic)] as electrochemical sensor for Hg2+ ions in CH3CN / H2O (v/v = 1/1). The oxidation wave intensity of [Ir(TPQ)2(4-EO2-pic)] at 0.98 V decreased and new reversible oxidation wave was appeared at 0.91 V The binding ratio of the [Ir(TPQ)2(4-EO2-pic)]-Hg2+ complex was determined to be 1:1 according to the Job’s Plot. The probable binding modes of these [Ir(TPQ)2(4-EO2-pic)] with Hg2+ have also been suggested on the basis of the 1H-NMR titration, absorption and luminescence studies.
关键词： Phosphorescent,Iridium(III) complex,Inkjet-printed,Paper sensor,Hg2+ detection
更新于2025-09-23 15:21:21
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Double-Emission Ratiometric Fluorescent Sensors Composed of Rare-Earth-Doped ZnS Quantum Dots for Hg <sup>2+</sup> Detection
摘要： Quantum dots (QDs) are a class of zero-dimensional nanocrystal materials, whose lengths are limited to 2?10 nm. Their unique advantages such as wide excitation spectra, narrow emission spectra, and high quantum yield make their application possible in ?uorescence sensing, wherein QDs such as CdSe, CdTe, and CdS are used. Indeed, QDs have a wide range of applications in ?uorescence sensing, and there have been many reports of applications based on QDs as ion probes. The emission spectra of QDs can be adjusted by changing the size of the QDs or doping them with other ions/elements. However, the high toxicity of Cd and the poor anti-interference ability of single-emission ?uorescent probes greatly limit the applications of QDs in many ?elds. In this paper, ZnS QDs are doped with the rare-earth element Ce to form a low-toxicity double-emission ratiometric ?uorescent sensor, ZnS:Ce, for Hg2+ detection. The results of transmission electron microscopy (TEM), X-ray di?ractometry, X-ray photoelectron spectroscopy, and optical spectroscopy show that ZnS:Ce QDs were successfully synthesized. Under the optimal conditions, the concentration of Hg2+ was in the range of 10?100 μM, which had a linear relationship with the ?uorescence intensity of the ZnS:Ce QDs: the linear correlation coe?cient was 0.998, and the detection limit was 0.82 μM L?1. In addition, the ?uorescent sensor had good selectivity for Hg2+, and it was successfully applied to the detection of Hg2+ in laboratory water samples.
关键词： ZnS:Ce,Hg2+ detection,Quantum dots,ratiometric fluorescent sensor,double-emission
更新于2025-09-23 15:19:57
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Cascade recognition of Hg <sup>2+</sup> and cysteine using a naphthalene based ESIPT sensor and its application in a set/reset memorized device
摘要： An optical ESIPT sensor for Hg2+ and cysteine based on a naphthalene platform (1) was designed and synthesized by a one step reaction and characterized by using common spectroscopic techniques. Upon addition of Hg2+ to a 9 : 1 (v/v) aqueous CH3CN (pH 7.0 HEPES buffer) solution of 1, the highly fluorescent probe becomes weakly fluorescent, showing a color change from colorless to dark yellow visible to the naked eye and from fluorescent blue to light yellow when irradiated with 365 nm light. The sensing mechanism has been supported by DFT and 1H NMR titration studies. The in situ generated 1–Hg2+ complex has been used for effectively sensing Cys. Owing to the stronger binding affinity of the sulfhydryl group to Hg2+, Cys can extract Hg2+ from the 1–Hg2+ complex, resulting in the release of 1 and revival of the emission intensity. Sensor 1 has also been successfully applied for the detection of Hg2+ in real water samples with good recovery. The alternate addition of Hg2+ and Cys ions generated "on–off–on" fluorescence cycles, which enabled 1 to be used as a reversible and reconfigurable set/reset memorized device at the molecular level.
关键词： molecular logic device,fluorescence,Hg2+ detection,cysteine sensing,ESIPT sensor
更新于2025-09-19 17:15:36
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Physicochemical and Ion-Sensing Properties of Benzofurazan-Appended Calix[4]arene in Solution and on Gold Nanoparticles: Spectroscopy, Microscopy, and DFT Computations in Support of the Species of Recognition
摘要： A calix[4]arene conjugate (L) functionalized at the lower rim with a benzofurazan fluorophore (NBD) and at the upper rim with a thioether moiety has been synthesized and characterized by 1H NMR, 13C NMR, and mass spectrometry techniques. Both the absorption and emission spectral data for L in different solvents exhibited progressive changes with an increase in polarity. Ion recognition studies were performed by absorption and fluorescence spectroscopy using 10 different metal ions. Among these, Hg2+ exhibited greater changes in these spectra, whereas Cu2+ showed only significant changes and all other ions showed no change in the spectral features. Although the Hg2+ has dominant influence on the spectral features and provides a detection limit of 56.0 ± 0.6 ppb, the selectivity was hampered because of the presence of the derivatizations present on both the rims of L for ion interaction in solution. Therefore, L was immobilized onto gold nanoparticles (AuNPL) so that the upper rim derivatizations anchor onto the gold surface through Au?S interactions, and this leaves out only the lower rim NBD derivatization for interaction with ions selectively. The AuNPL’s were characterized by transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy (XPS) analyses. The surface characteristics were analyzed by contact angle measurements. The AuNPL’s exhibit greater selectivity and enhanced sensitivity for Hg2+ ions with a lowest detection limit of 48.0 ± 0.8 ppb. The immobilization of L onto AuNPs was reflected in the corresponding fluorescence lifetime values, and the addition of Hg2+ to either L or AuNPL showed fluorescence quenching. The reversible recognition of Hg2+ by L was demonstrated by titrating L or AuNPL with Hg2+ followed by tetra-butyl ammonium iodide for several cycles. The structural features of Hg2+-bound species were demonstrated by density functional theory computations and were supported by the XPS data. The Hg2+ induces aggregated fibrillar morphology into supramolecular L, as demonstrated by microscopy when Hg2+ was added either to L or to AuNPL, supporting aggregation-caused quenching.
关键词： calix[4]arene,benzofurazan,Hg2+ detection,DFT computations,fluorescence quenching,gold nanoparticles
更新于2025-09-04 15:30:14