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Boron doped carbon dots as a multifunctional fluorescent probe for sorbate and vitamin B12
摘要： Boron doped carbon dots (B-CD) were synthesized by a one-step hydrothermal method using phenylboronic acid as the starting material. They have an average size of about 3.3 nm, with excitation/emission wavelength of 247/323 nm and a quantum yield of 12%. The B-CD is shown to be viable fluorescent probe for sorbate (PS) and vitamin B12 (VB12). The fluorescence (FL) of the B-CD is quenched in the presence of PS or VB12 mainly coming from inner filter effect (IFE), but F?rster resonance energy transfer (FRET) from the B-CD (as a donor) to PS/VB12 (as an acceptor) cannot be excluded. The probe enables PS to be detected by fluorometry with a linear response in the 0.20–24 μM concentration range and a 6.1 nM detection limit (at 3σ/slope). For VB12, the data are 0.20–30 μM and 8.0 nM.
关键词： Fluorescent probe,Sorbic acid,Fluorescence quenching ratios,Intra-day precision,Selectivity,Inter-day precision,Quenching mechanism,Real sample analysis
更新于2025-09-23 15:23:52
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Structure variation and luminescence enhancement of BaLaMg(Sb, Nb)O6:Eu3+ double perovskite red phosphors based on composition modulation
摘要： A series of BaLaMgSb1-xNbxO6:Eu3+ double perovskite red phosphors was successfully obtained. X-ray diffraction and Rietveld refinement analyses were conducted to determine the phase information and the detailed structure parameters. The coordinate variations of both La3+/Eu3+ and Sb5+/Nb5+ were discussed to elucidate the influence of B-site ion doping on the lattice variation. Luminescence properties, excitation and emission spectra, were presented to show the advantages of doping with Nb5+ ion. Ultraviolet-vis diffuse reflectance spectra were performed to reveal the reason for the decreased emission intensity under the charge transfer band excitation. Moreover, band gap energy was estimated to clarify the relationship between the increased intensity (λex = 395 and 465 nm) and Nb5+ concentration. Intensity ratios of I(615)/I(590) were performed to show the symmetry variation of the lattice. Thermal quenching property was also investigated and the quenching mechanism was discussed in detail based on the ionization process.
关键词： White LED,Structure variation,Thermal quenching mechanism,Double perovskite
更新于2025-09-23 15:23:52
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Fe3+-selective and sensitive “on-off” fluorescence probe based on the graphitic carbon nitride nanosheets
摘要： An effective and facile “on-off” fluorescence sensing approach for the determination of Fe3+ ion using a large area and relatively uniform size graphitic carbon nitride nanosheets (GCNS) was developed. The prepared GCNS have blue and stable emission, as well as excellent water dispersion, and were applied as an effective fluorescent probe that based on the quenched fluorescence for selective and sensitive detection of Fe3+ ion. Herein, we explain the ambiguous fluorescence quenching mechanism between the GCNS and Fe3+, which mainly springs from the redox potential and empty d orbital of Fe3+. The redox potential and unfilled d orbit of Fe3+ endow it excellent binding force with GCNS, which generates most obvious fluorescence quenching effect with respect to other metal ions. The limit of detection (LOD) for Fe3+ was found to be about 2.06 μM. Therefore, the prepared GCNS has the potential to be used as a fluorescent probe for detection.
关键词： nanosheets,fluorescence detection,g-C3N4,fluorescence quenching mechanism
更新于2025-09-23 15:21:01
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One-pot synthesis of carbon dots co-doped with N and S: high quantum yield governed by molecular state and fluorescence detection of Ag <sup>+</sup>
摘要： Fluorescent carbon-based nanoparticles, called chronically as carbon dots (CDs), were synthesised from citric acid (CA) and 2-Aminothiophenol (2AT) via an N and S co-doped hydrothermal method. After a series of micro-structural characterisation, N and S elements could be sufficiently doped by means of the heteroatom in the CDs solution. The as-prepared CDs solution showed blue colour fluorescence with the highest QY of 78.6%, and study on the UV–visible and PL spectra further revealed that the outstanding fluorescence of as-prepared CDs mainly originates from the generated molecular fluorophores instead of the surface state. Owing to the strong fluorescence, the as-prepared CDs can be used as a sensing probe for the detection of Ag+ with high sensitivity and selectivity. However, the changes of fluorescence intensity exhibited the complex nature of the quenching mechanism due to the –SH and –NH2 groups on the fringes of carbonaceous cores or molecular fluorophores to aggregate into another fluorescent cores with the assistance of Ag+ ions, which promises a new approach for efficient detection of Ag+ for the application in industrial pollutants.
关键词： Ag+,N-CDs,S,quenching mechanism,molecular fluorophores,higher QYs
更新于2025-09-19 17:15:36
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Ratiometric fluorometric determination of silver(I) by using blue-emitting silicon- and nitrogen-doped carbon quantum dots and red-emitting N-acetyl-L-cysteine-capped CdTe quantum dots
摘要： A ratiometric fluorometric assay for silver(I) is described. The method makes use of a dually emitting quantum dot hybrid, which is composed of (a) blue-fluorescent silicon- and nitrogen-doped carbon quantum dots (CQDs), and (b) of red-emitting CdTe quantum dots (QDs) capped with N-acetyl-L-cysteine. The red-emitting CdTe QDs undergo strong and specific quenching by Ag(I), whereas the blue-emitting N,Si-CQDs are not quenched. The two kinds of QDs are mixed and used as a ratiometric fluorescent probe. A linear relationship is found between the log of intensities [(I608/I441)0/(I608/I441)] and the concentration of Ag(I) in the range from 5.0–1000 nM, and the limit of detection (at S/N = 3) is 1.7 nM. Possible interferents (including 17 general metal ions, 12 anions and fulvic acid) do not interfere with the determination. The assay was successfully used for the determination of Ag(I) in surface water and wastewater samples. The fluorescence quenching mechanism of the ratiometric assay system was also discussed in detailed.
关键词： Fluorescence quenching mechanism,Surface water,Nitrogen-doped carbon dots,Silver ions,Silicon-doped carbon dots,Wastewaters,3-Aminopropyltriethoxysilane functionalized carbon dots,Quenching efficiency,Dual-emission quantum dots hybrid,Fluorescent probe
更新于2025-09-19 17:13:59
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Water-soluble ZnO quantum dots modified by (3-aminopropyl)triethoxysilane: The promising fluorescent probe for the selective detection of Cu2+ ion in drinking water
摘要： Copper, as an essential element in human body, can have adverse impact on environment and healthy individuals if it is excessive. So it is necessary to establish a rapid and effective method for detecting Cu2+. In this work, we describe a method for determination of Cu2+ based on water-soluble ZnO quantum dots (QDs) modified with (3-aminopropyl)triethoxysilane (APTEs). The ZnO QDs functionalized with APTEs (NH2-ZnO QDs) synthesized by a simple sol-gel method and displayed strong yellow-green fluorescence with a peak at 535 nm under 350 nm excitation. High-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, luminescence, and UV-visible absorption spectroscopy were used to characterize the NH2-ZnO QDs. In addition, the emission from NH2-ZnO QDs was selectively quenched upon addition of Cu2+. Therefore, this finding was used to design a fluorescent probe based on NH2-ZnO QDs to detect Cu2+ in water solution, and the linear relationships were 2-20 nM and 1-100 μM respectively, with detection limit for Cu2+ at 1.72 nM (on the basis of 3σ/slope criterion). This fluorescent probe had also been applied in real water sample to testify its availability in drinking water. Furthermore, the quenching mechanism was studied by measurements of UV-visible absorption spectra and fluorescent lifetime of ZnO QDs, which may be attributed to the aggregation induced by Cu2+ and the dynamic quenching existing energy transfer between QDs and Cu2+.
关键词： Drinking water,Water-soluble,Fluorescent probe,Cu2+ detection,ZnO QDs,Quenching mechanism
更新于2025-09-16 10:30:52