Co-reporter:Yan Liang, Hui Zhang, Yan Zhang and Fang Chen
Analytical Methods 2015 vol. 7(Issue 18) pp:7540-7547
Publication Date(Web):17 Jul 2015
DOI:10.1039/C5AY01301A
The present article reports on the one-step rapid green synthesis of water-soluble, fluorescent carbon nanodots (C-dots) with a quantum yield of 8.9%. Compared with previous hydrothermal methods, the proposed method is performed at lower temperature and results in larger size (20–30 nm) C-dots. We observed that UV-Vis absorbance at 302 nm of C-dots shows a significant linear correlation with the concentration of Hg2+ added, which indicates that the as-prepared carbon dots could act as a colorimetric probe for Hg2+. The linear range of this colorimetric probe is 1.0 × 10−9–7.0 × 10−7 mol L−1 and the detection limit is 5.7 × 10−10 mol L−1. Simultaneously, the fluorescence of the C-dots in pH 5.0 phosphate buffer solution can be dramatically quenched by Hg2+, whereas it is nearly unaffected by other metal ions. A good linear relationship exists between the quenching efficiency (F0/F) and the concentration of Hg2+ in the range of 7.0 × 10−9–7.0 × 10−7 mol L−1 with a detection limit (3σ) of 5.5 × 10−10 mol L−1. This dual probe for Hg2+ exhibits excellent performance in polluted tap water samples analysis, suggesting its promising application in the future.
Co-reporter:Yan Liang, Weizhou Liu, Hui Zhang and Fang Chen
Analytical Methods 2014 vol. 6(Issue 22) pp:9015-9021
Publication Date(Web):01 Sep 2014
DOI:10.1039/C4AY01656D
A novel chemosensor, 2-hydroxy-4-(pyridin-2-ylmethyleneamino)benzoic acid (PA) has been developed and found to be a selective fluorescent detector of Fe3+ over a wide range of treated metal ions. Because of the presence of carboxyl in PA, the fluorescence of this Schiff base could be reversibly controlled by alternately adding OH− and H+. In addition, because Fe3+ selectively quenches the fluorescence of PA, the quenched fluorescence can be recovered by adding EDTA as a competitor or NH2OH × HCl as a reducing agent. As a result, the fluorescence intensity of PA could be reversibly turned by H+/OH− or Fe3+/EDTA or NH2OH × HCl/K2S2O8 in an aqueous solution. These results demonstrated that PA along with a PA–Fe3+ system can perform not only as a reversible multi-control fluorescent switch, but also as a “NOR,” “OR” and “INHIBIT” logic gates. Furthermore, analytical application of this fluorescent probe was investigated and achieved promising and satisfying results.
Co-reporter:Biyun Fang, Yan Liang, Fang Chen
Talanta 2014 Volume 119() pp:601-605
Publication Date(Web):15 February 2014
DOI:10.1016/j.talanta.2013.11.066
•A Schiff base has been prepared for Cu2+ ions detection based on florescence quenching method.•The chemosensor shows an excellent specificity towards Cu2+ ions.•The florescence quenching mechanism is formation of a nonluminous complex.•Florescence switch character of the Schiff base has been explored.A sensitive and selective copper(II) fluorescence Schiff base chemical sensor receptor 1 (short for N,N′-bis(salicylidene)-o-phenylenediamine) has been prepared. The fluorescence of receptor 1 in pH 8.2 phosphate buffer solution can be dramatically quenched by Cu2+, whereas it is nearly unaffected by other metal ions. Based on this, a sensitive and selective fluorescent quenching method for Cu2+ detection has been established. Under the optimum conditions, a good linear relation exists between the quenching efficiency (F0/F) and the concentration of Cu2+ in the range of 1.0×10−7–2.5×10−6 mol L−1. The detection limit (3σ) for Cu2+ determination is 2.0×10−8 mol L−1. The present method has been successfully used for quantification of Cu2+ in soybean milk powder. Furthermore, the fluorescence switch property of the system was explored, and the system might be applied for determination of glutathione and construction of molecular logic gate.The fluorescence of N,N′-bis(salicylidene)-o-phenylenediamine can be dramatically quenched by Cu2+ ions through the formation of a (1:1, metal-to-ligand) complex and a new sensitive and selective “On–Off” fluorescence method could be developed for determination of Cu2+.
Co-reporter:Ting Wu;Biyun Fang;Lin Chang;Min Liu
Luminescence 2013 Volume 28( Issue 6) pp:894-899
Publication Date(Web):
DOI:10.1002/bio.2453
ABSTRACT
A simple spectrofluorimetric method is described for the determination of DNA, based on its enhancement of the fluorescence intensity of prulifloxacin (PUFX)–Tb3+. The luminescence intensity of the PUFX–Tb3+ complex increased up to 10-fold after adding DNA. The excitation and emission wavelengths were 345 and 545 nm, respectively. Under optimum conditions, variations in the fluorescence intensity showed a good linear relationship with the concentration of hsDNA in the range of 3.0 × 10-9 to 1.0 × 10-6 g/mL, with a correlation coefficient (R) of 0.997, and the detection limit was 2.1 × 10-9 g/mL. The method was successfully applied to the determination of DNA in synthetic samples, and recoveries were in the range 97.3–102.0%. The mechanism of fluorescence enhancement of the PUFX–Tb3+ complex by DNA is also discussed. The mechanism may involve formation of a ternary complex mainly by intercalation binding together with weak electrostatic interaction, which will increase the energy transition from ligand to Tb3+, increasing the rigidity of the complex, and decreasing the radiationless energy loss through O–H vibration of the H2O molecule in the PUFX–Tb3+ compl+osed method is not only more robust and friendly to the environment, but also of relatively higher sensitivity. Copyright © 2013 John Wiley & Sons, Ltd.
Co-reporter:Biyun Fang, Yan Liang, Ting Wu, Lin Chang, Quanyingg Zhou, Fang Chen
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2013 Volume 116() pp:440-445
Publication Date(Web):December 2013
DOI:10.1016/j.saa.2013.07.078
•A fluorometric method for determination of EDTA is proposed.•The method bases on EDTA recover the fluorescence of a shiff base quenched by Fe3+.•The fluorescence recovery mechanism is formation of a ternary complex.•The method shows high specificity and high sensitivity for EDTA detection.A fast and sensitive fluorometric method for determination of an emerging pollutant, ethylenediaminetetraacetic acid (EDTA), was proposed based on the reversion of fluorescence quenching of 2-pyridinecarbaldehyde-p-phenyldihydrazone by ferric iron. It was found that Fe3+ could selectively quench the fluorescence of 2PC-PPH, while EDTA could recover it due to its strong coordination ability with Fe3+. Based on this, we established an “Off and On” fluorescence method for determination of EDTA. Under the optimum conditions, the linear range and detection limit (3S/N) for EDTA determination were 2.0 × 10−6 ∼ 1.4 × 10−5 mol L−1 and 1.5 × 10−7 mol L−1, respectively. The relative standard deviation for the determination of 7.0 × 10−6 mol L−1 EDTA was 3.7% (n = 11). The method was successfully applied to determination of EDTA in tap water, lake water and investigating degradation of EDTA by TiO2/UV process.A simple and sensitive “Off–On” fluorescence method have been developed for EDTA determination based on EDTA could recover the fluorescence quenching of 2-pyridinecarbaldehyde-p-phenyldihydrazone (2PC-PPH) by ferric iron.
Co-reporter:Quanying Zhou, Weizhou Liu, Lin Chang, Fang Chen
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2012 Volume 92() pp:78-83
Publication Date(Web):15 June 2012
DOI:10.1016/j.saa.2012.02.049
The synthesis and spectral characterization of a schiff base, 2-pyridinecarbaldehyde-p-phenylenedihydrazone (short for 2PC-PPH), were described. It was found that ferric ion (Fe3+) could selectively quench the fluorescence of 2PC-PPH, whereas many other metal ions, such as Mn2+, Zn2+, Cu2+, K+, Al3+, Ca2+, Ni2+, Co2+, Cr3+ and Fe2+, could not quench its fluorescence. Based on this, a sensitive method for ferric ion selective detection was established. Under the optimum conditions, the decreasing fluorescence intensity of 2PC-PPH is proportional to the concentration of Fe3+ within the range of 6.0 × 10−7–1.0 × 10−5 mol L−1. The detection limit (3σ) for Fe3+ determination is 3.6 × 10−7 mol L−1. The proposed method was successfully applied to determine iron in tea and milk powder.Graphical abstractHighlights► The interaction between Fe3+ and a schiff base was studied by spectroscopy. ► Ferric ion could selectively quench the fluorescence of it. ► A sensitive method for ferric ion selective detection was established.
Co-reporter:Lin Chang;Ting Wu
Microchimica Acta 2012 Volume 177( Issue 3-4) pp:295-300
Publication Date(Web):2012 June
DOI:10.1007/s00604-011-0759-0
We report on a simple and sensitive method for the determination of L-cysteine (Cys). It is based on a redox reaction between the non-fluorescent Cu(II)-calcein complex and Cys which results in fluorescence recovery of calcein. When Cys is added to a solution of the Cu(II)-calcein complex, Cu(II) is reduced to Cu(I), and calcein is released to form a strongly fluorescent complex with Zn(II). The effect was used to develop a fluorescence enhancement method for the determination of Cys. Under the optimum conditions, the increase in signal intensity is linear in the range from 3.0 × 10−7 to 1.2 × 10−5 mol L−1, with a correlation coefficient (R) of 0.9978. The limit of detection (3σ) is 4.0 × 10−8 mol L−1. The relative standard deviation (RSD) in the determination of 11 samples containing 5.0 × 10−6 mol L−1 of Cys was 3.5%. There is little interference by common ions and other amino acids. The method, which is simple, rapid, and sensitive, was successfully applied to the determination of Cys in human serum samples.
Co-reporter:Fengshan Yu;Weizhou Liu;Ping Cai
Luminescence 2008 Volume 23( Issue 6) pp:429-433
Publication Date(Web):
DOI:10.1002/bio.1075
Abstract
The fluorescence of the prulifloxacin (PUFX)–Al(III) system was investigated . Experiments indicated that the fluorescence intensity of prulifloxacin could be greatly enhanced by Al(III) and sensitized by sodium dodecylbenzene sulphonate (SDBS). Accordingly, a sensitive spectrofluorimetric method for the determination of prulifloxacin was established. While excited at 275 nm, the enhanced fluorescence intensity at 412 nm of the system (ΔF) showed a good linear relationship with the concentration of prulifloxacin within the range 4.0 × 10–8–3.0 × 10–6 mol/L. The regression equation was ΔF = 9.83 + 10.8 × 107c (mol/L); the correlation coefficient and detection limit (3σ/k) were 0.99901 and 2.0 × 10–8 mol/L, respectively. The proposed method has been successfully applied to determine prulifloxacin in real pharmaceutical samples. The luminescence mechanism of the system is also discussed in detail. Copyright © 2008 John Wiley & Sons, Ltd.
Co-reporter:Jianping Huang;Zhike He
Microchimica Acta 2007 Volume 157( Issue 3-4) pp:181-187
Publication Date(Web):2007 March
DOI:10.1007/s00604-006-0653-3
A novel method for DNA detection is proposed that is based on the enhancement of resonance light scattering (RLS) of Ru(bpy)2PIP(V)2+ at pH 2.7. Under optimum conditions, good linear relationships were obtained in the wide concentration range of 16–5120 ng mL−1. The linear equation is IRLS = 13.15 + 171.4 c (µg mL−1), the correlation coefficient (r) is 0.9999. The detection limit of calf thymus DNA is 5.02 ng mL−1. Plasmid DNA extracted from bacillus subtilis was determined by the method with satisfactory results.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 22) pp:
Publication Date(Web):
DOI:10.1039/C4AY01656D
A novel chemosensor, 2-hydroxy-4-(pyridin-2-ylmethyleneamino)benzoic acid (PA) has been developed and found to be a selective fluorescent detector of Fe3+ over a wide range of treated metal ions. Because of the presence of carboxyl in PA, the fluorescence of this Schiff base could be reversibly controlled by alternately adding OH− and H+. In addition, because Fe3+ selectively quenches the fluorescence of PA, the quenched fluorescence can be recovered by adding EDTA as a competitor or NH2OH × HCl as a reducing agent. As a result, the fluorescence intensity of PA could be reversibly turned by H+/OH− or Fe3+/EDTA or NH2OH × HCl/K2S2O8 in an aqueous solution. These results demonstrated that PA along with a PA–Fe3+ system can perform not only as a reversible multi-control fluorescent switch, but also as a “NOR,” “OR” and “INHIBIT” logic gates. Furthermore, analytical application of this fluorescent probe was investigated and achieved promising and satisfying results.
Co-reporter:
Analytical Methods (2009-Present) 2015 - vol. 7(Issue 18) pp:NaN7547-7547
Publication Date(Web):2015/07/17
DOI:10.1039/C5AY01301A
The present article reports on the one-step rapid green synthesis of water-soluble, fluorescent carbon nanodots (C-dots) with a quantum yield of 8.9%. Compared with previous hydrothermal methods, the proposed method is performed at lower temperature and results in larger size (20–30 nm) C-dots. We observed that UV-Vis absorbance at 302 nm of C-dots shows a significant linear correlation with the concentration of Hg2+ added, which indicates that the as-prepared carbon dots could act as a colorimetric probe for Hg2+. The linear range of this colorimetric probe is 1.0 × 10−9–7.0 × 10−7 mol L−1 and the detection limit is 5.7 × 10−10 mol L−1. Simultaneously, the fluorescence of the C-dots in pH 5.0 phosphate buffer solution can be dramatically quenched by Hg2+, whereas it is nearly unaffected by other metal ions. A good linear relationship exists between the quenching efficiency (F0/F) and the concentration of Hg2+ in the range of 7.0 × 10−9–7.0 × 10−7 mol L−1 with a detection limit (3σ) of 5.5 × 10−10 mol L−1. This dual probe for Hg2+ exhibits excellent performance in polluted tap water samples analysis, suggesting its promising application in the future.
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