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1.
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   

2.
In this study, a multiplex fluorescence sensor for successive detection of Fe3+, Cu2+ and Hg2+ ions based on “on–off” of fluorescence of a single type of gold nanoclusters (Au NCs) is described. Any of the Fe3+, Cu2+ and Hg2+ ions can cause quenching fluorescence of Au NCs, which established a sensitive sensor for detection of these ions respectively. With the introduction of ethylene diamine tetraacetic acid (EDTA) to the system of Au NCs and metal ions, a restoration of fluorescence may be found with the exception of Hg2+. A highly selective detection of Hg2+ ion is, thus, achieved by masking Fe3+ and Cu2+. On the other hand, the masking of Fe3+ and Cu2+ leads to the enhancement of fluorescence of Au NCs, which in turn provides an approach for successive determination of Fe3+ and Cu2+ based on “on–off” of fluorescence of Au NCs. Moreover, this assay was applied to the successful detection of Fe3+, Cu2+ and Hg2+ in fish, a good linear relationship was found between these metal ions and the degree of quenched fluorescent intensity. The dynamic ranges of Hg2+, Fe3+ and Cu2+ were 1.96 × 10−10–1.01 × 10−9, 1.28 × 10−7–1.27 × 10−6 and 1.2 × 10−7–1.2 × 10−6 M with high sensitivity (the limit of detection of Fe3+ 2.0 × 10−8 M, Cu2+ 1.9 × 10−8 M and Hg2+ 2 × 10−10 M). These results indicate that the assay is suitable for sensitive detection of these metal ions even under the coexistence, which can not only determine all three kinds of metal ions successively but also of detecting any or several kinds of metal ions.  相似文献   

3.
In this study, we developed a fluorescence assay for the highly sensitive and selective detection of Hg2+ and Pb2+ ions using a gold nanoparticle (Au NP)-based probe. The Hg–Au and Pb–Au alloys that formed on the Au NP surfaces allowed the Au NPs to exhibit peroxidase-mimicking catalytic activity in the H2O2-mediated oxidation of Amplex UltraRed (AUR). The fluorescence of the AUR oxidation product increased upon increasing the concentration of either Hg2+ or Pb2+ ions. By controlling the pH values of 5 mM tris–acetate buffers at 7.0 and 9.0, this H2O2–AUR–Au NP probe detected Hg2+ and Pb2+ ions, respectively, both with limits of detection (signal-to-noise ratio: 3) of 4.0 nM. The fluorescence intensity of the AUR oxidation product was proportional to the concentrations of Hg2+ and Pb2+ ions over ranges 0.05–1 μM (R2 = 0.993) and 0.05–5 μM (R2 = 0.996), respectively. The H2O2–AUR–Au NP probe was highly selective for Hg2+ (>100-fold) and Pb2+ (>300-fold) ions in the presence of other tested metal ions. We validated the practicality of this simple, selective, and sensitive H2O2–AUR–Au NP probe through determination of the concentrations of Hg2+ and Pb2+ ions in a lake water sample and of Pb2+ ions in a blood sample. To the best of our knowledge, this system is the first example of Au NPs being used as enzyme-mimics for the fluorescence detection of Hg2+ and Pb2+ ions.  相似文献   

4.
Shi L  Song W  Li Y  Li DW  Swanick KN  Ding Z  Long YT 《Talanta》2011,84(3):900-904
A new sensing molecule 8-hydroxyquinoline ferrocenoate (Fc-Q) which combines ferrocene and 8-hydroxyquinoline moieties was synthesized and applied as a multi-channel sensor for the detection of Hg2+ ion. Fc-Q can coordinate with Hg2+ to give colorimetric, fluorescent and electrochemical responses. Upon complexation with Hg2+ ion, the characteristic absorption peak is red-shifted (Δλ = 45 nm), the fluorescent intensity is quenched at 303 nm, and the oxidation peak is cathodic shifted (ΔE1/2 = −149 mV). Quantitatively analyzed Hg2+ ions at the range of ppb level could be achieved by electrochemical response. For the practical application of sensing Hg2+ in real world water, Fc-Q modified screen-printed carbon electrodes were obtained for facile, sensitive, and on-site analysis of Hg2+.  相似文献   

5.
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 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   

7.
《中国化学会会志》2017,64(2):133-137
Metal cations can be selectively detected by restoring and quenching the fluorescent intensity of an “ON–OFF” gold nanocluster (Au NC ) sensor. The fluorescent intensity of Au NCs with metal cations can be restored by chelating with ethylenediaminetetraacetic acid except for Hg2+ ions. A highly selective detection of Hg2+ ion is also achieved under the coexistence of Fe3+ or Cr3+ ions. This assay was applied successfully for detecting Hg2+ in a water sample. The dynamic range of the system was 1 ppm to 25 ppb, and the limit of detection was 25 ppb.  相似文献   

8.
Several DNA templates with the sequence 5′‐T n TAACCCCTAACCCCT ‐3′ (n = 0, 15, 30, and 45) were used to prepare DNA template–silver nanoclusters (DNA –Ag NCs ). The T n sequence acts as a recognition element for Hg2+, while the rest of the sequence acts as a template for DNA –Ag NCs . At pH 3.0, the fluorescence intensity of DNA –Ag NCs is enhanced by ATP , and the enhanced fluorescence is quenched by Hg2+. The length of polyT shows a slight effect on the sensitivity for the detection of Hg2+ but almost no effect on the optical properties of DNA –Ag NCs . The fluorescence response of DNA –Ag NCs (T15‐DNA –Ag NCs ) vs. Hg2+ concentration shows two linear ranges over 10–100 and 100–1000 nM , mainly because of the fluorescence quenching due to DNA conformational changes through T–Hg2+–T coordination and the formation of an amalgam with Ag NCs , respectively. The sensitivity of the T15‐DNA –Ag NC probe was validated through the analysis of Hg2+ in spiked pond water. Based on the switch‐on and switch‐off fluorescence properties of T15‐DNA –Ag NCs , an IMPLICATION logic gate was fabricated using the concentrations of ATP and Hg2+ as inputs and the fluorescence intensity at 585 nm as output.  相似文献   

9.
An analytical method using an optical probe in a photoelectrochemical cell for the sensitive and selective determination of aqueous Hg2+ is presented. A previously synthesized Hg2+ selective chemosensor, proven to be Hg2+ sensitive up to 2 μg L−1, has been immobilized onto indium tin oxide (ITO) electrodes in a composite form with polyaniline. The coated ITO electrode was placed in a photoelectrochemical cell under closed circuit conditions in which the optical recognition of the chemosensor was converted to a measurable signal. A composite of the fluorescent chemosensor, Rhodamine 6G derivative (RS), and polyaniline (PANI) was immobilized on ITO glass plates and subjected to photovoltage measurements in the absence and presence of Hg2+. The optical responses of the coated electrode were used to determine the sensitivity and selectivity of the immobilized sensor to Hg2+ in the presence of background ions. The optical response of the PANI-dye coated electrode increased linearly with increasing Hg2+ concentration in the range 10-150 μg L−1, with a detection limit of 6 μg L−1.  相似文献   

10.
A fluorescent probe 1 for Hg2+ based on a rhodamine-coumarin conjugate was designed and synthesized. Probe 1 exhibits high sensitivity and selectivity for sensing Hg2+, and about a 24-fold increase in fluorescence emission intensity is observed upon binding excess Hg2+ in 50% water/ethanol buffered at pH 7.24. The fluorescence response to Hg2+ is attributed to the 1:1 complex formation between probe 1 and Hg2+, which has been utilized as the basis for the selective detection of Hg2+. Besides, probe 1 was also found to show a reversible dual chromo- and fluorogenic response toward Hg2+ likely due to the chelation-induced ring opening of rhodamine spirolactam. The analytical performance characteristics of the proposed Hg2+-sensitive probe were investigated. The linear response range covers a concentration range of Hg2+ from 8.0 × 10−8 to 1.0 × 10−5 mol L−1 and the detection limit is 4.0 × 10−8 mol L−1. The determination of Hg2+ in both tap and river water samples displays satisfactory results.  相似文献   

11.
Li Y  Wu P  Xu H  Zhang Z  Zhong X 《Talanta》2011,84(2):508-512
For the widely used gold nanoparticles (AuNPs)-based colorimetric probes, AuNPs generally change from dispersion to aggregation state accompanying with corresponding color turning from red to blue. Although colorimetric probes based on the anti-aggregation of AuNPs show exceptional selectivity and sensitivity, few examples have been reported in literature. A facile but highly sensitive and selective colorimetric probe based on the anti-aggregation of AuNPs transferred from the deactivation of aggregation agent 4,4′-dipyridyl by Hg2+ was developed in this work. This reported probe is suitable for real-time detection of Hg2+ in water with a detection limit of 3.0 ppb for Hg2+, and exhibits a selectivity toward Hg2+ by two orders of magnitude over other metal ions. The dynamic range of this probe can be conveniently tuned by adjusting the amount of 4,4′-dipyridyl used.  相似文献   

12.
Ju Hee Kim 《Tetrahedron letters》2004,45(41):7557-7561
A new ionophore having two pyrenylacetamide moieties based on the p-tert-butylcalix[4]arene-diaza-crown ether has been prepared and its fluoroionophoric properties were investigated. Bis(pyrenyl) derivative was found to exhibit selective ON-OFF type sensing behavior toward Hg2+ ions over other representative transition and heavy metal ions. The fluorescence quenching efficiency of larger than 20-fold was observed with 100 equiv of Hg2+ ions and the association constant was found to be 4.5 × 104 M−1 in methanol. The ionophore also exhibited a very efficient quenching of excimer fluorescence selectively upon treatment with Hg2+ ions in 50% aqueous methanol solution. The observed Hg2+-selective ON-OFF type fluorescence behavior could be utilized as efficient sensing and switching devices for the design of other supramolecular systems.  相似文献   

13.
A novel reaction-based probe for fluorescence signaling of Hg2+ ions was developed. Selective Hg2+-induced cleavage of a dithioacetal resulting in switching from pyrene excimer to monomer emission was used for the signaling. Changes in excimer and monomer emissions of pyrene were readily employed for ratiometric signaling of Hg2+ ions in aqueous acetonitrile. Selective signaling of Hg2+ ions over other common metal ions was observed with a detection limit of 9.8 × 10−7 M.  相似文献   

14.
New dioxocyclam derivatives bearing two anthracene fluorophores were prepared, and their fluoroionophoric properties toward transition metal ions were investigated. Chemosensor 2 having anthrylacetamide moieties exhibited pronounced Hg2+- and Cu2+-selective fluoroionophoric properties in aqueous acetonitrile solution over other representative transition metal ions, as well as alkali and alkaline earth metal ions. Chemosensor 2 also exhibited Hg2+ and Cu2+ selectivity under competitive conditions in the presence of physiologically and environmentally important metal ions. The detection limits for the sensing of Hg2+ and Cu2+ ions were 7.8 × 10−6 and 1.5 × 10−6 M, respectively, in aqueous 95% acetonitrile solution.  相似文献   

15.
We propose a simple, economical, and one-pot method to synthesize water-soluble functionalized fluorescent carbon dots (C-Dots) through electrochemical carbonization of sodium citrate and urea. The as-prepared C-Dots have good photostability and exhibit a high quantum yield of 11.9%. The sizes of the C-Dots are mainly distributed in the range of 1.0–3.5 nm with an average size of 2.4 nm. It has been further used as a novel label-free sensing probe for selective detection of Hg2+ ions with detection limit as low as 3.3 nM. The detection linear range is 0.01–10 μM. The as-prepared C-Dots are also successfully applied for the determination of Hg2+ in real water samples.  相似文献   

16.
Lin YW  Liu CW  Chang HT 《Talanta》2011,84(2):324-329
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   

17.
A new indole-based fluorescent chemosensor 1 was prepared and its metal ion sensing properties were investigated. It exhibits high sensitivity and selectivity toward Hg2+ among a series of metal ions in H2O-EtOH (7:1, v/v). The association constant of the 1:1 complex formation for 1-Hg2+ was calculated to be 9.57 × 103 M−1, and the detection limit for Hg2+ was found to be 2.25 × 10−5 M. Computational results revealed that 1 and Hg2+ ion formed with a central tetrahedron-coordinated Hg2+.  相似文献   

18.
A new chemically modified carbon paste electrode was constructed and used for rapid, simple, accurate, selective and highly sensitive simultaneous determination of cadmium, copper and mercury using square wave anodic stripping voltammetry (SWASV). The carbon paste electrode was modified by N,N′-bis(3-(2-thenylidenimino)propyl)piperazine coated silica nanoparticles. Compared with carbon paste electrode, the stripping peak currents had a significant increase at the modified electrode. Under the optimized conditions (deposition potential, −1.100 V vs. Ag/AgCl; deposition time, 60 s; resting time, 10 s; SW frequency, 25 Hz; pulse amplitude, 0.15 V; dc voltage step height, 4.4 mV), the detection limit was 0.3, 0.1 and 0.05 ng mL−1 for the determination of Cd2+, Cu2+ and Hg2+, respectively. The complexation reaction of the ligand with several metal cations in methanol was studied and the stability constants of the complexes were obtained. The effects of different cations and anions on the simultaneous determination of metal ions were studied and it was found that the electrode is highly selective for the simultaneous determination of Cd2+, Cu2+ and Hg2+. Furthermore, the present method was applied to the determination of Cd2+, Cu2+ and Hg2+ in water and some foodstuff samples.  相似文献   

19.
Diametrically disubstituted bis(anthrylmethyl) derivative of 1,8-dimethylcyclam exhibited pronounced Hg2+- and Cd2+-selective fluorogenic behaviors in aqueous acetonitrile solution. A distinctive OFF-ON type signaling was observed for Hg2+ and Cd2+ ions in aqueous acetonitrile (CH3CN-H2O = 90:10, v/v) solution, while a selective ON-OFF type switching behavior toward Hg2+ ions was observed in solution having higher water content (CH3CN-H2O = 50:50, v/v). The detection limit for the analysis of Hg2+ ions in 50% aqueous acetonitrile was found to be 3.8 × 10−6 M. The selective OR logic gate behavior of the prepared compound toward two toxic heavy metal ions of Hg2+ and Cd2+ ions in CH3CN-H2O (90:10, v/v) suggests the possibility as a new chemosensing device for the two important target metal ions.  相似文献   

20.
In this paper, a simple, selective and reusable electrochemical biosensor for the sensitive detection of mercury ions (Hg2+) has been developed based on thymine (T)-rich stem–loop (hairpin) DNA probe and a dual-signaling electrochemical ratiometric strategy. The assay strategy includes both “signal-on” and “signal-off” elements. The thiolated methylene blue (MB)-modified T-rich hairpin DNA capture probe (MB-P) firstly self-assembled on the gold electrode surface via Au–S bond. In the presence of Hg2+, the ferrocene (Fc)-labeled T-rich DNA probe (Fc-P) hybridized with MB-P via the Hg2+-mediated coordination of T–Hg2+–T base pairs. As a result, the hairpin MB-P was opened, the MB tags were away from the gold electrode surface and the Fc tags closed to the gold electrode surface. These conformation changes led to the decrease of the oxidation peak current of MB (IMB), accompanied with the increase of that of Fc (IFc). The logarithmic value of IFc/IMB is linear with the logarithm of Hg2+ concentration in the range from 0.5 nM to 5000 nM, and the detection limit of 0.08 nM is much lower than 10 nM (the US Environmental Protection Agency (EPA) limit of Hg2+ in drinking water). What is more, the developed DNA-based electrochemical biosensor could be regenerated by adding cysteine and Mg2+. This strategy provides a simple and rapid approach for the detection of Hg2+, and has promising application in the detection of Hg2+ in real environmental samples.  相似文献   

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