Co-reporter:Chenxia Hao, Tao Zhou, Shaopu Liu, Linlin Wang, Bowen Huang, Nianxi Kuang, Youqiu He
Journal of Colloid and Interface Science 2016 Volume 472() pp:76-83
Publication Date(Web):15 June 2016
DOI:10.1016/j.jcis.2016.03.017
•A dual-channel optical sensing platform has been designed for the detection of DA.•The sensing platform combines the advantages of DWO-RRS and fluorescence.•The possible mechanism of the sensing system was also explored.•The proposed method has been successfully applied to the detection of DA in the milk samples.A dual-channel optical sensing platform which combines the advantages of dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) and fluorescence has been designed for the detection of diminazene aceturate (DA). It is based on the use of thioglycolic acid-wrapped CdTe/CdS quantum dots (Q-dots). In the absence of DA, the thioglycolic acid-wrapped CdTe/CdS Q-dots exhibit the high fluorescence spectrum and low RRS spectrum, so are selected to develop an easy-to-get system. In the presence of DA, the thioglycolic acid-wrapped CdTe/CdS Q-dots and DA form a complex through electrostatic interaction, which result in the RRS intensity getting enhanced significantly with new RRS peaks appearing at 317 and 397 nm; the fluorescence is powerfully quenched. Under optimum conditions, the scattering intensities of the two peaks are proportional to the concentration of DA in the range of 0.0061–3.0 μg mL−1. The detection limits for the two single peaks are 4.1 ng mL−1 and 3.3 ng mL−1, while that of the DWO-RRS method is 1.8 ng mL−1, indicating that the DWO-RRS method has high sensitivity. Besides, the fluorescence also exhibits good linear range from 0.0354 to 10.0 μg mL−1 with a detection limit of 10.6 ng mL−1. In addition, the system has been applied to the detection of DA in milk samples with satisfactory results.We design a dual-channel optical sensing platform which combines the advantages of dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) and fluorescence for the detection of diminazene aceturate (DA). The proposed method has been applied successfully to the detection of DA in milk samples.
Co-reporter:Linlin Wang, Shaopu Liu, Chenxia Hao, Xiaolong Zhang, Chaoqun Wang, Youqiu He
Sensors and Actuators B: Chemical 2016 Volume 229() pp:145-154
Publication Date(Web):28 June 2016
DOI:10.1016/j.snb.2016.01.117
•A dual-fluorescence “turn off–on” biosensor was designed to detect herring sperm DNA.•The reactions among different kinds of phenazinium dyes, QDs, and DNA were studied.•This biosensor exhibited high sensitivity and good selectivity for DNA detection.A dual-fluorescence “turn off–on” biosensor, which consists of quantum dots (GSH-CdTe QDs) whose fluorescence was quenched by safranine T (ST) via an electron transfer process, had been developed for herring sperm DNA (hsDNA) detection. Initially, in the “turn off” stage, the strong fluorescence of GSH-CdTe QDs could be effectively quenched by ST owing to the occurrence of the electron transfer from the photoexcited GSH-CdTe QDs to ST. And then, the high affinity of DNA to ST enabled the ST attached to the surface of GSH-CdTe QDs, to become embedded into hsDNA double helix structure to form stable complex and moved away from the QDs. Therefore, the recognition of hsDNA could be realized via the fluorescence restoration of the QDs–ST based biosensor, namely of the fluorescence “turn on” procedure. This designed biosensor exhibited good sensitivity and selectivity, for the reason that the detection limit for DNA reached 10.8 ng/mL, meanwhile, neither biologically relevant metal ions, common organic compounds, nor the amino acid had any significant interference in the detection mode. Hence, this simple, fast, sensitive, and selective biosensor owned perfect analysis applications in biochemical DNA monitoring.
Co-reporter:Linlin Wang, Shaopu Liu, Wanjun Liang, Dan Li, Jidong Yang, Youqiu He
Journal of Colloid and Interface Science 2015 Volume 448() pp:257-264
Publication Date(Web):15 June 2015
DOI:10.1016/j.jcis.2015.02.034
A fluorescent “turn off–on” pattern for the detection of herring sperm DNA (hsDNA) had been designed through utilizing the interaction between polymyxin B sulfate (PMBS) and hsDNA as an inherent performance and the fluorescent transformation of glutathione (GSH)-capped CdTe quantum dots (QDs) as an external manifestation. Due to the occurrence of the photoinduced electron transfer from the QDs to PMBS, the fluorescence of GSH-capped CdTe QDs could be effectively quenched by PMBS, causing the system into “off” state. With the addition of hsDNA, the quenched fluorescence of GSH-capped CdTe QDs could be restored for the reason that PMBS embedded into hsDNA double helix structure to form new complex and peeled off from the surface of GSH-capped CdTe QDs, leading the system into “on” condition. Corresponding experimental results illustrated that the relative recovered fluorescence intensity of GSH-capped CdTe QDs–PMBS system was near proportional to the concentration of hsDNA within the range of 0.059–15.0 μg mL−1. This proposed method demonstrated a good linear correlation coefficient of 0.9937 and a detection limit (3 σ/K) of 0.018 μg mL−1 for hsDNA. This dual-directional fluorescent biosensor overcame the selectivity problem commonly existed in the traditional mono-directional fluorescence detection mode and owned perfect analysis applications in biochemical DNA monitoring.Graphical abstract
Co-reporter:Wanjun Liang, Shaopu Liu, Zhengqing Liu, Dan Li, Linlin Wang, Chenxia Hao and Youqiu He
New Journal of Chemistry 2015 vol. 39(Issue 6) pp:4774-4782
Publication Date(Web):30 Mar 2015
DOI:10.1039/C4NJ01764A
A simple and sensitive fluorescence “turn-off” biosensor for detection of vancomycin at nanogram level was proposed based on the electron transfer mechanism and the fluorescence quenching of CdTe quantum dots (QDs). The electron transfer process during the interaction between vancomycin and GSH (glutathione)-CdTe QDs was investigated not only by ultraviolet/visible (UV/vis) absorption and fluorescence (FL) spectroscopy but also by fluorescence lifetime measurements. The degree of the electron transfer and as resulted fluorescence quenching was proportional to the increasing of vancomycin concentration in the range of 1.534 ng mL−1–20 μg mL−1, with a corresponding detection limit of 0.4605 ng mL−1. This proposed a biosensor that could be used to determine vancomycin in environmental water samples, pharmaceutical formulation and spiked human serum with all of the recoveries over 95.8%. The mechanism of the detection was dynamic quenching with an electron transfer (ET) process. The experimental conditions, key affecting factors and the influence of the coexisting substances have also been optimized and studied.
Co-reporter:Wanjun Liang;Shaopu Liu;Jing Song;Chenxia Hao;Linlin Wang
Biotechnology Letters 2015 Volume 37( Issue 5) pp:1057-1061
Publication Date(Web):2015 May
DOI:10.1007/s10529-015-1767-7
A sensitive fluorescence biosensor for determining sparfloxacin (SPF) based on the electron transfer mechanism and the fluorescence quenching effect of SPF to cadmium telluride quantum dots (CdTe QDs) was developed. The mechanism of the interaction between SPF and CdTe QDs was investigated by UV/Vis absorption and fluorescence spectroscopy. The biosensor could be used for the determination of SPF with a high sensitivity. Under optimum conditions, the linear range was from 0.28 to 40 μg SPF ml−1 with a correlation coefficient of 0.9983, and the detection limit (3δ/k) was 83.7 ng SPF ml−1. Furthermore, this method has been applied to the determination of SPF in the synthetic environmental water samples and the spiked human serum samples with good results.
Co-reporter:Linlin Wang, Yizhong Shen, Shaopu Liu, Jidong Yang, Wanjun Liang, Dan Li, Youqiu He
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2015 Volume 136(Part C) pp:1607-1613
Publication Date(Web):5 February 2015
DOI:10.1016/j.saa.2014.10.054
•Interactions of topotecan hydrochloride, neutral red and quantum dots were studied.•Research on the reaction mechanisms were performed by various optical measurements.•The results were good for achieving the controlling of the fluorescent reversible regulation of QDs.The interactions of topotecan hydrochloride (THC), neutral red (NR) and thioglycolic acid (TGA) capped CdTe/CdS quantum dots (QDs) built a solid base for the controlling of the fluorescent reversible regulation of the system. This study was developed by means of ultraviolet–visible (UV–vis) absorption, fluorescence (FL), resonance Rayleigh scattering (RRS) spectroscopy and transmission electron microscopy (TEM). Corresponding experimental results revealed that the fluorescence of TGA-CdTe/CdS QDs could be effectively quenched by NR, while the RRS of the QDs enhanced gradually with the each increment of NR concentration. After the addition of THC, the strong covalent conjugation between NR and THC which was in carboxylate state enabled NR to be dissociated from the surface of TGA-CdTe/CdS QDs to form more stable complex with THC, thereby enhancing the fluorescence of the TGA-CdTe/CdS QDs-NR system. What is more, through analyzing the optical properties and experimental data of the reaction between TGA-CdTe/CdS QDs and NR, the possible reaction mechanism of the whole system was discussed. This combination of multiple spectroscopic techniques could contribute to the investigation for the fluorescent reversible regulation of QDs and a method could also be established to research the interactions between camptothecin drugs and dyes.Graphical abstract
Co-reporter:Dan Li;Shaopu Liu;Yizhong Shen;Jidong Yang
Luminescence 2015 Volume 30( Issue 1) pp:60-66
Publication Date(Web):
DOI:10.1002/bio.2690
Abstract
Water-soluble thioglycolic acid (TGA)-capped core/shell CdTe/CdS quantum dots (QDs) were synthesized. The interactions of rhein and emodin with TGA-CdTe/CdS QDs were evaluated by fluorescence and ultraviolet-visible absorption spectroscopy. Experimental results showed that the high fluorescence intensity of TGA-CdTe/CdS QDs could be effectively quenched in the presence of rhein (or emodin) at 570 nm, which may have resulted from an electron transfer process from excited TGA-CdTe/CdS QDs to rhein (or emodin). The quenching intensity was in proportion to the concentration of both rhein and emodin in a certain range. Under optimized conditions, the linear ranges of TGA-CdTe/CdS QDs fluorescence intensity versus the concentration of rhein and emodin were 0.09650–60 µg/mL and 0.1175–70 µg/mL with a correlation coefficient of 0.9984 and 0.9965, respectively. The corresponding detection limits (3σ/S) of rhein and emodin were 28.9 and 35.2 ng/mL, respectively. This proposed method was applied to determine rhein and emodin in human urine samples successfully with remarkable advantages such as high sensitivity, short analysis time, low cost and easy operation. Based on this, a simple, rapid and highly sensitive method to determine rhein (or emodin) was proposed. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Chenxia Hao;Shaopu Liu;Dan Li;Jidong Yang
Luminescence 2015 Volume 30( Issue 7) pp:1112-1118
Publication Date(Web):
DOI:10.1002/bio.2867
Abstract
A sensitive and simple analytical strategy for the detection of sodium cromoglycate (SCG) has been established based on a readily detectable fluorescence quenching effect of SCG for glutathione-capped (GSH-capped) CdTe quantum dots (QDs). The fluorescence of GSH-capped CdTe QDs could be efficiently quenched by SCG through electron transfer from GSH-capped CdTe QDs to SCG. Under optimum conditions, the response was linearly proportional to the concentration of SCG between 0.6419 and 100 µg/mL, with a correlation coefficient (R) of 0.9964; the detection limit (3δ/K) was 0.1926 µg/mL. The optimum conditions and the influence of coexisting foreign substances on the reaction were also investigated. The very effective and simple method reported here has been successfully applied to the determination of SCG in synthetic and real samples. It is believed that the established approach could have good prospects for application in the fields of clinical diseases diagnosis and treatment. Copyright © 2015 John Wiley & Sons, Ltd.
Co-reporter:Chenxia Hao;Shaopu Liu;Wanjun Liang;Dan Li;Linlin Wang
Microchimica Acta 2015 Volume 182( Issue 11-12) pp:2009-2017
Publication Date(Web):2015 August
DOI:10.1007/s00604-015-1543-3
We report on a simple, sensitive and regenerable fluorescent nanoprobe for Zn(II) ion. It is based on the use of glutathione capped CdTe quantum dots (GSH-CdTe Q-dots). The bright fluorescence of these Q-dots is quenched on addition of diethylenetriaminepentaacetic acid (DTPA) due to the binding of DTPA to GSH. If, however, Zn(II) is added, it will bind DTPA and detach it from the surface of the Q-dots, this resulting in the fluorescence recovery. Under optimum conditions, the intensity of the restored fluorescence is proportional to the concentration of Zn(II) in the 0.48 to 90 μmol · L−1 range, with a limit of detection of 0.14 μmol · L−1. The nanoprobe was applied to the determination of Zn(II) in spiked tap water and river water and gave satisfactory results. The findings were also applied to design a molecular logic gate where DTPA acts as the first input to the system by quenching the fluorescence of the GSH-CdTe Q-dots. Zn(II) acts as the second input and causes the detachment of DTPA from the Q-dots and a restoration of fluorescence. This system therefore represents a new IMP (IMPLICATION) logic gate.
Co-reporter:Yizhong Shen, Shaopu Liu, Ling Kong, Xuanping Tan, Youqiu He and Jidong Yang
Analyst 2014 vol. 139(Issue 22) pp:5858-5867
Publication Date(Web):26 Aug 2014
DOI:10.1039/C4AN01180E
Although various strategies have been reported for double-stranded DNA (DNA) detection, development of a time-saving, specific, and regeneratable fluorescence sensing platform still remains a desired goal. In this study, we proposed a new DNA detection method that relies on an “off-on” switch of a regenerated fluorescence biosensor based on an electron transfer mechanism from glutathione (GSH)-capped CdTe quantum dots (QDs) to nile blue (NB). Initially, the high fluorescence of GSH-capped CdTe QDs could be effectively quenched by NB due to the binding of NB to the GSH on the surface of the QDs and the electron transfer from the photoexcited GSH-capped CdTe QDs to NB. Then, the high affinity of DNA to NB enabled the NB to be dissociated from the surface of GSH-capped CdTe QDs to form a more stable complex with DNA and suppress the electron transfer process between GSH-capped CdTe QDs and NB, thereby restoring the fluorescence of NB surface modified GSH-capped CdTe QDs (QDs–NB). In addition, we have testified the regenerability of the proposed DNA senor. The corresponding result shows that this DNA sensor is stable for two reuses. This fluorescence “off-on” signal was sensitive to the concentration of DNA in the range from 0.0092 to 25.0 μg mL−1 with a good correlation coefficient of 0.9989, and the detection limit (3σ/S) was 2.78 ng mL−1. To further investigate for perfect analysis performance, the developed biosensor was applied for the determination of DNA in human fresh serum samples with satisfactory results.
Co-reporter:Yizhong Shen, Shaopu Liu, Jidong Yang, Linlin Wang, Xuanping Tan, Youqiu He
Sensors and Actuators B: Chemical 2014 199() pp: 389-397
Publication Date(Web):
DOI:10.1016/j.snb.2014.04.014
Co-reporter:Yizhong Shen;Shaopu Liu
Luminescence 2014 Volume 29( Issue 2) pp:176-182
Publication Date(Web):
DOI:10.1002/bio.2525
ABSTRACT
Water-soluble glutathione (GSH)-capped core/shell CdTe/CdS quantum dots (QDs) were synthesized. In pH 5.4 sodium phosphate buffer medium, the interaction between GSH-CdTe/CdS QDs and sanguinarine (SA) was investigated by spectroscopic methods, including fluorescence spectroscopy and ultraviolet-visible absorption spectroscopy. Addition of SA to GSH-CdTe/CdS QDs results in fluorescence quenching of GSH-CdTe/CdS QDs. Quenching intensity was in proportion to the concentration of SA in a certain range. Investigation of the quenching mechanism, proved that the fluorescence quenching of GSH-CdTe/CdS QDs by SA is a result of electron transfer. Based on the quenching of the fluorescence of GSH-CdTe/CdS QDs by SA, a novel, simple, rapid and specific method for SA determination was proposed. The detection limit for SA was 3.4 ng/mL and the quantitative determination range was 0.2–40.0 µg/mL with a correlation coefficient of 0.9988. The method has been applied to the determination of SA in synthetic samples and fresh urine samples of healthy human with satisfactory results. Copyright © 2013 John Wiley & Sons, Ltd.
Co-reporter:Yizhong Shen;Shaopu Liu;Lei Wang;Pengfei Yin
Luminescence 2014 Volume 29( Issue 7) pp:884-892
Publication Date(Web):
DOI:10.1002/bio.2637
ABSTRACT
Novel, water-soluble CdTe quantum dots (QDs) capped with β-cyclodextrin (β-CD) and ~ 4.0 nm in diameter were synthesized in aqueous solution, and characterized using transmission electron microscopy (TEM). A fluorescence-sensing system based on the photoinduced electron transfer (PET) of (mono-6-thio-β-CD)–CdTe QDs was then designed to measure the interaction of phenothiazine dyes [methylene blue (MB) and methylene green (MG)] with herring sperm DNA (hsDNA). This fluorescence-sensing system was based on a fluorescence “OFF–ON” mode. First, MB/MG adsorbed on the surface of (mono-6-thio-β-CD)–CdTe QDs effectively quenches the fluorescence of (mono-6-thio-β-CD)–CdTe QDs through PET. Then, addition of hsDNA restores the fluorescence intensity of (mono-6-thio-β-CD)–CdTe QDs, because hsDNA can bind with MB/MG and remove it from the as-prepared (mono-6-thio-β-CD)–CdTe QDs. In addition, detailed reaction mechanisms of the (mono-6-thio-β-CD)–CdTe QDs–MB/MG–hsDNA solution system were studied using optical methods, by comparison with the TGA–CdTe QDs–MB/MG–hsDNA solution system. Copyright © 2014 John Wiley & Sons, Ltd.
Co-reporter:Wanjun Liang, Zhengqing Liu, Shaopu Liu, Jidong Yang, Youqiu He
Sensors and Actuators B: Chemical 2014 196() pp: 336-344
Publication Date(Web):
DOI:10.1016/j.snb.2014.02.026
Co-reporter:Yizhong Shen, Shaopu Liu, Jian Wang, Dan Li, Xiaodan Wang and Youqiu He
Analytical Methods 2013 vol. 5(Issue 19) pp:5309-5316
Publication Date(Web):05 Aug 2013
DOI:10.1039/C3AY40792F
A sensitive and simple method for the determination of chelerythrine (CHE) was developed based on the fluorescence quenching effect of CHE for glutathione (GSH)-capped CdTe/CdS quantum dots (QDs). Under optimum conditions, a good linear relationship was obtained from 0.073 to 24.0 μg mL−1 with a correlation coefficient of 0.9988, and the detection limit (3σ/κ) was 21.9 ng mL−1. The fluorescence quenching mechanism that has been proposed is based on electron transfer supported by ultraviolet-visible (UV-vis) absorption, fluorescence (FL) spectroscopy and electrochemical techniques. The method has been applied to the determination of CHE in synthetic samples and fresh serum samples from healthy humans with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.
Co-reporter:Yizhong Shen, Shaopu Liu, Jian Wang, Dan Li and Youqiu He
Analytical Methods 2013 vol. 5(Issue 13) pp:3228-3234
Publication Date(Web):19 Apr 2013
DOI:10.1039/C3AY40365C
A sensitive and simple method for the determination of ellagic acid (EA) was developed based on the fluorescence quenching effect of EA for glutathione (GSH)-capped CdTe quantum dots (QDs). Under optimum conditions, a good linear relationship was obtained from 0.3118 to 55.0 μg mL−1 with a correlation coefficient of 0.9983, and the detection limit (3σ/K) was 0.0936 μg mL−1. The fluorescence quenching mechanism has been proposed on the basis of electron transfer supported by ultraviolet-visible (UV-vis) absorption, fluorescence (FL) spectroscopy and the measurement of fluorescence lifetime. The method has been applied to the determination of EA in synthetic samples and fresh urine samples of healthy humans with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.
Co-reporter:Pingping Li;Shaopu Liu;Xiaodan Wang;Zhengqing Liu
Luminescence 2013 Volume 28( Issue 6) pp:910-914
Publication Date(Web):
DOI:10.1002/bio.2456
ABSTRACT
The ineraction between riboflavin (RBF) and tryptophan (Trp) was investigated using fluorescence spectroscopy and UV–vis absorption spectroscopy under physiological conditions. The fluorescence of Trp was quenched by RBF via dynamic quenching, which was analyzed using the Stern–Volmer relation. The value of the Forster distance R0 (2.31 nm) was obtained according to the Forster's theory of nonradiative energy transfer. Under physiological conditions, a linear relationship could be established between the quenched fluorescence intensity of Trp and the concentration of RBF in the range of 5.8 × 10-7–2.0 × 10-5 mol/L. The detection limit was 1.8 × 10-7 mol/L. The method was successfully applied to determine riboflavin concentrations in pharmaceutical samples. Copyright © 2012 John Wiley & Sons, Ltd.
Co-reporter:Xiaodan Wang, Pingping Li, Zhengqing Liu, Youqiu He
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2013 Volume 421() pp:118-124
Publication Date(Web):20 March 2013
DOI:10.1016/j.colsurfa.2012.12.045
3-mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs) were synthesized with a diameter of about 3 nm in aqueous solution which were characterized by transmission electron microscopy (TEM) and fluorescence microscopy. The interaction between the two flavonoids (baicalein and hesperetin) and QDs was investigated by fluorescence, ultraviolet–visible (UV–vis) absorption spectroscopy, and electrochemical measurement. The fluorescence of QDs was quenched by baicalein and hesperetin via electron transfer progress. Additionally, the reason of different fluorescence quenching efficiency of QDs by baicalein and hesperetin was discussed, and it revealed that the fluorescence quenching efficiency of QDs is partly related to the antioxidant activity of flavonoids. Based on this, a simple and sensitive assay for determination of baicalein and hesperetin was proposed. Under the optimized conditions, the linear range of QDs fluorescence intensity versus the concentration of baicalein and hesperetin were 0.032–50 μg/mL and 0.082–120 μg/mL, with correlation coefficient (R) of 0.9977 and 0.9963, and limit of detections (3σ) of 9.736 ng/mL and 24.46 ng/mL, respectively. The presented method has been applied successfully for the determination of baicalein and hesperetin in urine samples.Electron transfer from baicalein and hesperetin to the valence band hole of the excited state of QDs lead to the fluorescence quenching of QDs, which was demonstrated by fluorescence spectra, electrochemical measurement and ultraviolet–visible absorption spectra etc.Highlights► Strong fluorescence intensity of QDs was quenched by baicalein and hesperetin. ► Electron transfer from flavonoids to QDs is suggested as the sensing mechanism. ► Quenching level of QDs related to different antioxidant activity of flavonoids. ► Rapid and simple methods for determining baicalein and hesperetin were proposed.
Co-reporter:Yizhong Shen, Shaopu Liu, Ling Kong, Dan Li, Youqiu He
Sensors and Actuators B: Chemical 2013 Volume 188() pp:555-563
Publication Date(Web):November 2013
DOI:10.1016/j.snb.2013.07.070
Thioglycolic acid-capped (TGA-capped) CdTe/CdS quantum dots (QDs) were prepared in the water phase. The interaction of TGA-CdTe/CdS QDs with polymyxin B sulfate (POBS) was investigated by ultraviolet–visible (UV–vis) absorption, fluorescence (FL), resonance Rayleigh scattering (RRS) spectroscopy and the measurement of fluorescence lifetime. Under optimum conditions, not only the UV–vis absorption and fluorescence spectra were changed, but also the RRS intensity was greatly enhanced. These phenomena offered useful techniques for the determination of POBS with fluorescence quenching and RRS methods. The linear ranges and detection limits of POBS were 0.09–5.25 μg mL−1 and 27.5 ng mL−1 for the fluorescence quenching technique, 0.02–6.0 μg mL−1 and 6.36 ng mL−1 for the RRS technique. Among them, the RRS approach obtained the higher sensitivity. Accordingly, a novel rapid, convenient, and highly sensitive RRS method for the determination of POBS was proposed and applied to detect POBS in pharmaceutical preparations with satisfactory results. Furthermore, the suitable reaction conditions, affecting factors as well as the influence of coexisting substances were studied. Some possible reaction mechanisms were also discussed.
Co-reporter:Zhengqing Liu, Shaopu Liu, Pengfei Yin, Youqiu He
Analytica Chimica Acta 2012 Volume 745() pp:78-84
Publication Date(Web):1 October 2012
DOI:10.1016/j.aca.2012.07.033
A novel fluorescent probe for Cu2+ determination based on the fluorescence quenching of glyphosate (Glyp)-functionalized quantum dots (QDs) was firstly reported. Glyp had been used to modify the surface of QDs to form Glyp-functionalized QDs following the capping of thioglycolic acid on the core–shell CdTe/CdS QDs. Under the optimal conditions, the response was linearly proportional to the concentration of Cu2+ between 2.4 × 10−2 μg mL−1 and 28 μg mL−1, with a detection limit of 1.3 × 10−3 μg mL−1 (3δ). The Glyp-functionalized QDs fluorescent probe offers good sensitivity and selectivity for detecting Cu2+. The fluorescent probe was successfully used for the determination of Cu2+ in environmental samples. The mechanism of reaction was also discussed.Graphical abstractGlyphosate (Glyp) had been used to modify the surface of CdTe/CdS QDs, resulting in the enhancement of fluorescence intensity. The Glyp-functionalized QDs fluorescent probe offers good sensitivity and selectivity for detecting Cu2+ based on the fluorescence quenching.Highlights► Water soluble CdTe/CdS quantum dots capped with glyphosate were firstly synthesized. ► The fluorescence of the Glyp-functionalized QDs was quenched by copper ion. ► A new fluorescent sensor for copper ion was developed based on the prepared QDs. ► The sensor exhibited high sensitivity and good selectivity for copper ion.
Co-reporter:Zhengqing Liu, Pengfei Yin, Huiping Gong, Pingping Li, Xiaodan Wang, Youqiu He
Journal of Luminescence 2012 Volume 132(Issue 9) pp:2484-2488
Publication Date(Web):September 2012
DOI:10.1016/j.jlumin.2012.03.072
Aqueous glutathione (GSH)-capped CdTe/ZnS QDs with the diameter of 3–4 nm were synthesized. The fluorescence of CdTe/ZnS QDs at 577 nm was quenched in the presence of rifampicin (Rfp), with excitation wavelength at 350 nm. The mechanism of the interaction of CdTe/ZnS QDs with Rfp was investigated. Under the optimal conditions, the calibration plot of ln(F0/F) was linear in the range 0.83–56 μg mL−1 with concentration of Rfp, and the detection limit was 0.25 μg mL−1. The proposed method was successfully applied to the determination of Rfp in its commercial capsules, and satisfactory results were obtained. The recovery of the method was in the range 98.6–103.2%.Highlights► Fluorescence of CdTe/ZnS QDs was found to be quenched notably by rifampicin. ► A simple, rapid and sensitive fluorimetric method for the determination of Rfp was developed. ► Interaction mechanism of CdTe/ZnS QDs with rifampicin was investigated. ► Proposed method was applied for analysis of rifampicin in capsules.
Co-reporter:Xiaoqing Fan, Juanjuan Peng, Shuguang Yan, Lei Wang, Youqiu He
Journal of Luminescence 2011 Volume 131(Issue 10) pp:2230-2236
Publication Date(Web):October 2011
DOI:10.1016/j.jlumin.2011.04.033
Luminescent CdTe quantum dots (QDs) were synthesized using thioglycolic acid (TGA) as a stabilizing agent in aqueous medium and were characterized by Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and transmission electron microscopy (TEM). In weak basic media the fluorescence of TGA–CdTe QDs was quenched notably by ferulic acid (FA) and protocatechuic aldehyde (PA), and the quenching values were proportional to the concentration of the quenchers in a certain range. The addition of bovine serum albumin (BSA) to TGA–CdTe QDs–FA and TGA–CdTe QDs–PA systems rendered a large recovery of the fluorescence of TGA–CdTe QDs.Highlights► TGA coated CdTe QDs were synthesized in aqueous medium. ► Ferulic acid and protocatechuic aldehyde quenched the fluorescence of CdTe QDs. ► Adding BSA to quenching systems recovers the fluorescence of CdTe QDs.
Co-reporter:Youqiu He, Pengfei Yin, Huiping Gong, Juanjuan Peng, Shaopu Liu, Xiaoqing Fan, Shuguang Yan
Sensors and Actuators B: Chemical 2011 Volume 157(Issue 1) pp:8-13
Publication Date(Web):20 September 2011
DOI:10.1016/j.snb.2011.03.019
CdTe quantum dots (QDs) were synthesized in aqueous solution using 2-mercaptoethylamine hydrochloride (CA) as stabilizing agents. The interaction between CA-CdTe QDs with human serum albumin (HSA) was investigated by ultraviolet–visible (UV–vis) absorption, circular dichroism (CD), fluorescence and resonance Rayleigh scattering (RRS) spectroscopy. CD spectra revealed that the conformation and microenvironment of HSA were changed in the presence of CA-CdTe QDs. CA-CdTe QDs could strongly quench the intrinsic fluorescence of HSA by static quenching. The electrostatic interaction plays a major role in stabilizing the complex. The binding site number n and apparent binding constant K, corresponding thermodynamic parameters ΔG°, ΔH° and ΔS° at different temperatures were calculated. The interaction between CA-CdTe QDs and HSA led to the remarkable enhancement of RRS and the enchantments were in proportional to the concentration of HSA in the range 0.05 × 10−7 to 4.0 × 10−7 mol L−1 and a detection limit of 4.2 × 10−9 mol L−1. Based on this, RRS methods to determinate HSA were developed. The influences of factors on the interaction between HSA with CA-CdTe QDs and some foreign substances were all examined, which showed that the method had a good sensitivity and selectivity. In addition, the reasons for the enhancement of RRS were investigated.
Co-reporter:Pingping Li, Shaopu Liu, Shuguang Yan, Xiaoqing Fan, Youqiu He
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 Volume 392(Issue 1) pp:7-15
Publication Date(Web):5 December 2011
DOI:10.1016/j.colsurfa.2011.08.037
Based on CdTe/CdS quantum dots (CdTe/CdS QDs) fluorescence (FL) reversible control, a new and sensitive FL sensor for determination of anthraquinone (AQ) anticancer drugs (adriamycin and daunorubicin) and herring sperm DNA (hsDNA) was developed. Under the experimental conditions, FL of CdTe/CdS QDs can be effectively quenched by AQ anticancer drugs due to the binding of AQ anticancer drugs on the surface of CdTe/CdS QDs and photoinduced electron transfer (PET) process from CdTe/CdS QDs to AQ anticancer drugs. Addition of hsDNA afterwards brought the restoration of CdTe/CdS QDs FL intensity, as AQ anticancer drugs peeled off from the surface of CdTe/CdS QDs and embedded into hsDNA double helix structure. The liner ranges and the detection limits of FL quenching methods for two AQ anticancer drugs were 0.33–9 μg mL−1 and 0.09 μg mL−1 for ADM and 0.15–9 μg mL−1 and 0.04 μg mL−1 for DNR, respectively. The restored FL intensity was proportional to concentration of hsDNA in the range of 1.38–28 μg mL−1and the detection limit for hsDNA was 0.41 μg mL−1. It was applied to the determination of AQ anticancer drugs in human serum and urine samples with satisfactory results. The reaction mechanism of CdTe/CdS QDs FL reversible control was studied.Graphical abstractThe CdTe/CdS QDs FL intensity was restored with the increasing of concentration of hsDNA and it was almost completely restored when 28 μg mL−1 hsDNA was added into CdTe/CdS QDs-ADM system. According to the result, FL restoration method can be applied to determination of hsDNA.Highlights► Fluorescence of CdTe/CdS QDs was quenched by anthraquinone anticancer drugs due to photoinduced electron transfer process. ► Addition of hsDNA brought the restoration of CdTe/CdS QDs fluorescence intensity. ► A new fluorescence sensor for the determination of anthraquinone anticancer drugs and hsDNA in aqueous was developed.
Co-reporter:Xiaoqing Fan, Shaopu Liu, Youqiu He
Colloids and Surfaces B: Biointerfaces 2011 Volume 88(Issue 1) pp:23-30
Publication Date(Web):1 November 2011
DOI:10.1016/j.colsurfb.2011.05.029
This paper describes the synthesis of CdTe quantum dots (QDs) together capped by glutathione and thioglycolic acid (GSH and TGA) in aqueous solution. The narrow photoluminescence (fwhm ≤ 40 nm) CdTe QDs, whose emission spans most of the visible spectrum from green through red, has a quantum yield (QY) of 68% at room temperature. GSH/TGA-CdTe QDs are characterized by various experimental techniques such as optical absorption, photoluminescence and AFM measurements. Coumaric acid and caffeic acid is able to quench the fluorescence of GSH/TGA-CdTe QDs, and the fluorescence intensity is linearly proportional to the concentration of quenchers. The addition of bovine serum albumin (BSA) restores the fluorescence intensity of GSH/TGA-CdTe QDs-coumaric acid system and GSH/TGA-CdTe QDs-caffeic acid system. The fluorescence recovery was due to the interaction of BSA with coumaric acid and caffeic acid, leading to the freeing of the GSH/TGA-CdTe QDs. The fluorescence quenching mechanism of GSH/TGA-CdTe QDs was discussed. The binding constant and thermodynamics parameters of BSA–coumaric acid and BSA–caffeic acid during the binding process were calculated in the paper.Graphical abstractAFM images of GSH/TGA-CdTe QDs.Highlights► GSH/TGA-CdTe QDs are well-dispersed and spherical. ► The fluorescence of CdTe QDs was found to be quenched notably by coumaric acid and caffeic acid. ► The addition of bovine serum albumin (BSA) restores the fluorescence intensity of GSH/TGA-CdTe QDs-coumaric acid system and GSH/TGA-CdTe QDs-caffeic acid system.
Co-reporter:Lei Wang;ShaoPu Liu;JuanJuan Peng
Science China Chemistry 2010 Volume 53( Issue 6) pp:1358-1365
Publication Date(Web):2010 June
DOI:10.1007/s11426-010-3092-2
This paper presents a novel method for the synthesis of CdTe quantum dots (QDs) capped with β-cyclodextrin in aqueous solution using both TGA and mono-6-thio-β-CD as stabilizers. The interaction between mono-6-thio-β-CD-CdTe QDs and neutral red (NR) was studied with fluorescence, UV-absorption and the resonance Rayleigh scattering spectrum. When its concentration was over 7.5 × 10−6 mol/L, the neutral red began to aggregate on the surface of the mono-6-thio-β-CD-CdTe QDs, which resulted in the mono-6-thio-β-CD-CdTe QDs particle size increasing, the sharply quenched fluorescence, and the marked increase of RRS intensity.
Co-reporter:Lei Wang;Juanjuan Peng;Zhengwen Liu
Luminescence 2010 Volume 25( Issue 6) pp:424-430
Publication Date(Web):
DOI:10.1002/bio.1170
Abstract
A novel method is used for the determination of some aminoglycoside antibiotics (AGs) such as etimicin (ETM), isepamicin (ISP) and amikacin (AMK). It is based on the resonance Rayleigh scattering (RRS) intensities enhanced by AGs-induced CdTe quantum dots aggregation. Under the optimum conditions, the increments in RRS intensity were directly proportional to the concentration of AGs in certain ranges. At the same time, the second-order scattering, the frequency-doubling scattering and the frequency-trebling scattering intensities were also enhanced and their increments were proportional to the concentration of AGs. Among them, the RRS method had the highest sensitivity; the linear ranges and detection limits for ETM, ISP and AMK were 0.085–7.2, 0.0067–1.2, 0.017–6.0 and 0.025, 0.0051, 0.0020 μg mL−1. This method was applied to the measurement of AGs in human serum and urine with satisfactory results. In addition, the reaction mechanism and the reasons for the enhancement of RRS are discussed using fluorescence, RRS, transmission electron microscope technology and quantum chemistry method. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Juanjuan Peng, Shaopu Liu, Shuguang Yan, Xiaoqing Fan, Youqiu He
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 359(1–3) pp:13-17
Publication Date(Web):20 April 2010
DOI:10.1016/j.colsurfa.2010.01.027
Thioglycolic acid (TGA) capped CdTe quantum dots (QDs) with the diameter of 2–3 nm were synthesized. The interaction between CdTe QDs and chymotrypsin (chy) was investigated by ultraviolet–visible (UV–vis) absorption, fluorescence and resonance Rayleigh scattering (RRS) spectroscopy. Under pH 7.2, CdTe QDs effectively quenched the intrinsic fluorescence of chy via static quenching. The binding constants for the formation of a complex between CdTe QDs and chy were 2.85, 2.58, 2.48 × 103 M−1 at 293, 298 and 303 K, respectively. ΔS° (49.72 kJ mol−1) and ΔH° (−4.61 kJ mol−1) indicated that electrostatic attraction was the dominant intermolecular forces in stabilizing the complex. The interaction between CdTe QDs and chy lead to the remarkable enhancement of RRS and the enchantments were in proportional to the concentration of chy in a certain range. The reasons for the enhancement of RRS were discussed. The experimental results showed that chy molecules have a relatively high affinity with CdTe QDs.
Co-reporter:Juan-Juan Peng, Shao-Pu Liu, Lei Wang, You-Qiu He
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2010 Volume 75(Issue 5) pp:1571-1576
Publication Date(Web):May 2010
DOI:10.1016/j.saa.2010.02.021
Thioglycolic acid (TGA) capped CdTe quantum dots (QDs) with the diameter of 2–3 nm were synthesized. The interaction between CdTe QDs and Nile blue (NB) was investigated by ultraviolet–visible (UV–vis) absorption, resonance Rayleigh scattering (RRS) and fluorescence spectroscopy. UV–vis absorption spectrum of CdTe QDs and NB obviously changed, showing that CdTe QDs could associate with NB to form a new complex. At pH 6.8, NB effectively quenched the fluorescence of CdTe QDs. It was proved that the fluorescence quenching of CdTe QDs by NB was mainly result of the formation of CdTe QDs–NB complex, electrostatic attraction and hydrophobic forces played a major role in stabilizing the complex. The binding molar ratio of CdTe QDs and NB was 5:1 by a mole-ratio method. The interaction between CdTe QDs and NB lead to the remarkable enhancement of RRS and the enchantments were in proportional to the concentration of NB in a certain range. The mechanism of the interaction between CdTe QDs and NB, reasons for the enhancement of RRS intensity were also discussed. The obtained results suggested the more satisfactory mechanism for the interaction between CdTe QDs and NB.
Co-reporter:Zhengwen Liu, Shaopu Liu, Lei Wang, Juanjuan Peng, Youqiu He
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2009 Volume 74(Issue 1) pp:36-41
Publication Date(Web):15 September 2009
DOI:10.1016/j.saa.2009.04.026
In pH 6.6 Britton–Robinson buffer medium, the CdS quantum dots capped by thioglycolic acid could react with aminoglycoside (AGs) antibiotics such as neomycin sulfate (NEO) and streptomycin sulfate (STP) to form the large aggregates by virtue of electrostatic attraction and the hydrophobic force, which resulted in a great enhancement of resonance Rayleigh scattering (RRS) and resonance non-linear scattering such as second-order scattering (SOS) and frequency doubling scattering (FDS). The maximum scattering peak was located at 310 nm for RRS, 568 nm for SOS and 390 nm for FDS, respectively. The enhancements of scattering intensity (ΔI) were directly proportional to the concentration of AGs in a certain ranges. A new method for the determination of trace NEO and STP using CdS quantum dots probe was developed. The detection limits (3σ) were 1.7 ng mL−1 (NEO) and 4.4 ng mL−1 (STP) by RRS method, were 5.2 ng mL−1 (NEO) and 20.9 ng mL−1 (STP) by SOS method and were 4.4 ng mL−1 (NEO) and 25.7 ng mL−1 (STP) by FDS method, respectively. The sensitivity of RRS method was the highest. The optimum conditions and influence factors were investigated. In addition, the reaction mechanism was discussed.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 19) pp:
Publication Date(Web):
DOI:10.1039/C3AY40792F
A sensitive and simple method for the determination of chelerythrine (CHE) was developed based on the fluorescence quenching effect of CHE for glutathione (GSH)-capped CdTe/CdS quantum dots (QDs). Under optimum conditions, a good linear relationship was obtained from 0.073 to 24.0 μg mL−1 with a correlation coefficient of 0.9988, and the detection limit (3σ/κ) was 21.9 ng mL−1. The fluorescence quenching mechanism that has been proposed is based on electron transfer supported by ultraviolet-visible (UV-vis) absorption, fluorescence (FL) spectroscopy and electrochemical techniques. The method has been applied to the determination of CHE in synthetic samples and fresh serum samples from healthy humans with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 13) pp:
Publication Date(Web):
DOI:10.1039/C3AY40365C
A sensitive and simple method for the determination of ellagic acid (EA) was developed based on the fluorescence quenching effect of EA for glutathione (GSH)-capped CdTe quantum dots (QDs). Under optimum conditions, a good linear relationship was obtained from 0.3118 to 55.0 μg mL−1 with a correlation coefficient of 0.9983, and the detection limit (3σ/K) was 0.0936 μg mL−1. The fluorescence quenching mechanism has been proposed on the basis of electron transfer supported by ultraviolet-visible (UV-vis) absorption, fluorescence (FL) spectroscopy and the measurement of fluorescence lifetime. The method has been applied to the determination of EA in synthetic samples and fresh urine samples of healthy humans with satisfactory results. The proposed method manifested several advantages such as high sensitivity, short analysis time, low cost and ease of operation.
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