Sensitivity For Hg2 Research Articles

Modification-free and N-acetyl-L-cysteine-induced colorimetric response of AuNPs: A mechanistic study and sensitive Hg2+ detection

A facile yet sensitive and selective method was proposed for Hg2+ detection based on N-acetyl-L-cysteine(NAC)-induced colorimetric response of AuNPs. The proposed method can be easily performed by introducing the premixing of NAC and Hg2+ into as-prepared citrate-capped AuNPs solution. A combination of experimental and theoretical studies was applied to illustrate the mechanism of this AuNPs colorimetric system. The strong interaction of NAC and AuNPs through Au–S bond could lead to the aggregation of AuNPs, but the formation of NAC-Hg-NAC complex decreased the affinity between NAC and AuNPs and resulted in an anti-aggregation effect. Therefore, the color of the AuNPs solution would progress from purple to red with the increase of Hg2+ concentration. The proposed method had a high sensitivity with a limit of detection of 9.9nM. Coexistent metal ions, including Cd2+, Mn2+, Al3+, Ag+, K+, Mg2+, Ca2+, Cr3+, Cu2+, Fe3+, Pb2+, Ni2+ and Zn2+, did not interfere with the detection of Hg2+. This method can be used to monitor Hg2+ in tap water.

Promoted colorimetric response of spirooxazine derivative: a simple assay for sensitive mercury(II) detection

A spirooxazine derivative 1,3-dihydro-1,3,3-trimethyl-spiro[2-H-indole-2-2′-[2H-1,4] oxazino [2,3-f] [1, 10] phenanthroline] (compound 1) was explored as a sensitive Hg2+ probe. Sensing behavior toward various metal ions including Hg2+, Na+, K+, Ag+, Pb2+, Ni2+, Fe2+, Cu2+, Zn2+, Cd2+, Co2+, Ba2+, Mn2+, Cr3+, Al3+ and Fe3+ was investigated by UV–Vis in acetonitrile solution. Benefiting from the strategy of visual detection, this compound showed preferable selectivity and sensitivity for Hg2+ with a detection limit of 0.68 ppm. In addition, the color of the solution was different, when dropping different concentrations of mercury ions (10−8–10−2 M) into the probe (compound 1). This remarkable color variation (lavender to green) could be observed easily by a naked eye. The approach can not only detect the Hg2+ in acetonitrile solution, but also can detect the Hg2+ in sewage and industrial effluents.

Highly sensitive and selective Hg2+-chemosensor based on dithia-cyclic fluorescein for optical and visual-eye detections in aqueous buffer solution

A new fluorescent sensor (FC4) based on fluorescein dithia-cyclic skeleton was designed and prepared as a fluoroionophore for the optical and visual-eye detections of Hg2+ in aqueous buffer solution. FC4 was prepared via Kornblum oxidation, ester hydrolysis, alkylation, imine formation and imine reduction. The sensor provided highly sensitive and selective ON–OFF fluorescence sensing toward Hg2+ and was shown to discriminate various interfering metal ions, particularly Cu2+ and Pb2+ as well as Al3+, Ba2+, Ca2+, Cd2+, Fe3+, K+, Mg2+, Mn2+, Na+ and Ni2+. Sensor FC4 also exhibited chromogenic change upon binding to Hg2+, which served as a “visual-eye” indicator which could be observed as a noticeable change of the solution color from yellow to orange. The Hg2+ detection limit of the sensor was 7.38×10−9 or 1.48ppb which was lower than a permissible concentration of Hg2+ in drinking water regulated by the United States Environmental Protection Agency (U.S. EPA).

A reversible and highly selective phosphorescent sensor for Hg2+ based on iridium (III) complex

A novel reversible phosphorescent sensor for Hg2+ based on a neutral iridium (III) complex Ir(TBT)2(pic) (TBT=2-thiophen-2-yl-benzothiazole, pic=picolinate) has been synthesized and characterized. Ir(TBT)2(pic) displayed relatively strong phosphorescent nearly centered at about 600 nm. Upon addition of acetonitrile (CH3CN) solution of Hg2+, the dichloromethane (DCM) solution of Ir(TBT)2(pic) gave a visual color change from orange to yellow and significant phosphorescent quenching. It can serve as a highly selective sensor for Hg2+ with naked-eye detection. The sensor allow determination of Hg2+ in the working range of 4.0 μM–12.0 μM with a detection limit of 1.04 μM. When mixing with Hg2+, Ir(TBT)2(pic) interacted with Hg2+ in a 1:2 stoichiometry via a coordination bond interaction between the sulfur atom and Hg2+. The phosphorescent chemosensor exhibited excellent selectivity and sensitivity for Hg2+ detection. The spectral response of Ir(TBT)2(pic) toward Hg2+ was proved to be reversible.

A Fluorescent Probe for Hg2+ Based on Gold(I) Complex with An Aggregation‐Induced Emission Feature

AbstractA gold(I) complex that exhibited aggregation‐induced emission in acetonitrile‐water mixtures was designed. It showed high selectivity and sensitivity for Hg2+ in acetonitrile‐H2O (1:1, V:V) solution. Dynamic light scattering measurements were conducted to verify that the addition of Hg2+ changed the particle size and induced fluorescence quenching.

Facile synthesis of oxygen and sulfur co-doped graphitic carbon nitride fluorescent quantum dots and their application for mercury(ii) detection and bioimaging

We developed a facile one-step route for the synthesis of blue fluorescent OS-GCNQDs, which exhibited improved selectivity and sensitivity for Hg2+ detection, and lower cytotoxicity for cell imaging.

Facile synthesis of fluorescent polyaniline microspheres and their use for the detection of mercury ions

Bright blue fluorescent polyaniline microspheres were prepared by a simple controlled oxidation under mild conditions. A simple, highly sensitive fluorometric Hg2+ probe has been constructed.

Ethynyl and π-stacked thymine–Hg2+–thymine base pairs enhanced fluorescence quenching via photoinduced electron transfer and simple and sensitive mercury ion sensing

Ethynyl triggered enhanced fluorescence quenching effect was first reported based on photoinduced electron transfer (PET) between fluorophore and ethynyl. Ethynyl and 6-carboxyl-fluorescein (FAM) were labeled at the 5′- and 3′-termini of a poly d(T) sequence containing three thymine units, respectively. In the presence of Hg2+, Hg2+ binds to two thymine residues through T–Hg2+–T interactions and the formed T–Hg2+–T base pairs bring FAM and ethynyl from two matched sequences into close proximity. On the one hand, π-stacked T–Hg2+–T mediates and accepts electron transfer of the excited state of FAM and quenches the fluorescence through PET. On the other hand, π-stacked interactions between ethynyl and FAM also provide a de-excitation process for the excited state of FAM via PET and trigger an enhanced fluorescence quenching. On the basis of fluorescence quenching, a simple, rapid, and sensitive Hg2+ sensor was constructed; under optimum conditions, a good linear relationship was obtained over the concentration range of 5–150nM for Hg2+ and a very low detection limit (0.42nM) was reached. The developed system was further designed as a cysteine (Cys) sensor based on fluorescence recovery resulted from the strong interaction between Cys and Hg2+; the proposed Cys sensor has a linear range of 10–550nM and a detection limit of 2.5nM. The two sensors were used for analysis of real samples and the satisfactory results were achieved.

A fluorescent biosensor based on carbon dots-labeled oligodeoxyribonucleotide and graphene oxide for mercury (II) detection

As the newest two members of the carbon materials family, carbon dots (CDs) and graphene oxide (GO) possess many excellent optical properties resulting in a wide range of applications. In this work, we successfully synthesized CDs with a high-quantum-yield, and labeled them on oligodeoxyribonucleotide (ODN). The fluorescence of resultant CDs-labeled oligodeoxyribonucleotide (ODN–CDs) was quenched by GO via fluorescence resonance energy transfer. In the presence of Hg2+, the fluorescence was recovered by the release of ODN–CDs from GO due to the formation of T–Hg2+–T duplex. In the light of this theory, we designed a simple, highly sensitive and selective fluorometric Hg2+ sensor based on CDs-labeled oligodeoxyribonucleotide and GO without complicated, costly and time-consuming operations. Under the optimal conditions, a linear relationship was obtained between relative fluorescence intensity and the concentration of Hg2+ in the range of 5–200nM (R2=0.974). The present GO-based sensor system is highly selective toward Hg2+ over a wide range of metal ions and has a detection limit of 2.6nM. This method is reliable, and has been successfully applied for the detection of Hg2+ in practical samples.

Functional dialkylimidazolium-mediated synthesis of silver nanocrystals with sensitive Hg2+-sensing and efficient catalysis

Thiol-functionalized dialkylimidazolium bromide was synthesized, and used as a stabilizer to prepare monodisperse silver nanocrystals through a facile one-pot aqueous approach. It is shown that the multipurpose ligands play a vital role in improving the performance of nanocrystals. The mechanisms of dialkylimidazolium-mediated promotion were analyzed on the basis of the physicochemical properties of the specifically designed ligand.

A novel colorimetric and off–on fluorescent sensor for Hg2+ and its application in live cell imaging

A novel rhodamine-based fluorescent probe L2 with two “S” groups was synthesized and characterized. As expected, L2 exhibited high selectivity and sensitivity for Hg2+ over other commonly coexistent metal ions. Its selectivity is excellent, and the detection limit was measured to be 1ppm. The significant changes in the fluorescence color could be used for naked-eye detection. Furthermore, fluorescence imaging experiments of Hg2+ ions in living EC-109 cells demonstrated its value of practical applications in biological systems.

New rhodamine dimer probes for mercury detection via color changes and enhancement of the fluorescence emission: Fast recognition in cellulose supported devices

Two rhodamine dimer compounds exhibiting high selectivity and sensitivity for Hg2+ over other metal cations have been studied in absolute ethanol solution. Increase in the absorption and emission signals with a color change from colorless to pink were observed in both cases. Recognition of Hg2+ with both compounds in the gas phase was also explored. Immobilization of the rhodamine probes in cellulose supported systems to evaluate their efficiency on the fast detection of Hg2+ in aqueous phase was also reported.

Fluorescent and colorimetric magnetic microspheres as nanosensors for Hg2+ in aqueous solution prepared by a sol–gel grafting reaction and host–guest interaction

Fluorescent sensing TSRh6G-β-cyclodextrin fluorophore/adamantane-modified inclusion complex magnetic nanoparticles (TFIC MNPs) have been synthesized via the cooperation of a host-guest interaction and sol-gel grafting reaction. Powder X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and UV-visible absorption and emission spectroscopy have been employed to characterize the material. Fluorescence and UV-visible spectra have shown that the resultant multifunctional nanoparticle sensors exhibit selective 'turn-on' type fluorescent enhancements and a clear color change from light brown to pink with Hg(2+). Owing to a larger surface area and high permeability, TFIC MNPs exhibit remarkable selectivity and sensitivity for Hg(2+), and its detection limit measures up to the micromolar level in aqueous solution. Most importantly, magnetic measurements have shown that TFIC magnetic nanoparticles are superparamagnetic and they can be separated and collected easily using a commercial magnet. These results not only solve the limitations in practical sensing applications of nanosensors, but also enable the fabrication of other multifunctional nanostructure-based hybrid nanomaterials.

A highly selective off–on fluorescent chemodosimeter for Hg2+ based on a anthracene–bis(phosphinesulfide) conjugate

A chemodosimeter Ph2P(S)NP(–S–CH2–anthracene)Ph2 (L1), featuring the methylanthracenyl moiety covalently linked to one of the two S atoms of an S,S′-tetraphenyldithioimidodiphosphinate (L) unit exhibited good selectivity and sensitivity for Hg2+ in an aqueous environment. The chemical reaction involved differs from those reported in the literature for other Hg2+ chemodosimeters: the binding of Hg2+ induces the cleavage of the PS–CH2 bond to form the stable neutral complex [HgL2] and an emissive anthracenyl derivative. The X-ray crystal structure of L1 is reported (CCDC number 919620).

Fluorescence ‘on-off-on’ chemosensor for sequential recognition of Fe3+ and Hg2+ in water based on tetraphenylethylene motif

A novel selective and sensitive fluorescence ‘on-off-on’ probe based on tetraphenylethylene (TPE) motif for sequential recognition of Fe3+ and Hg2+ in water has been developed. Especially the complex 6-Fe3+ could behave as a ‘turn on’ fluorescent sensor over a wide-range pH value for detection of Hg2+. The selectivity of this complex for Hg2+ over other heavy and transition metal ions is excellent, and its sensitivity for Hg2+ is at 2ppb in water.

Indenofluorene based water soluble conjugated oligomers for Hg2+ detection

Three novel indenofluorene based cationic conjugated oligomers, PIFPC, PIFTC, and PIF2TC, have been designed and synthesized. The optical and electrochemical behaviors of these oligomers have been studied. These high charge density oligomers exhibit good water solubility as high as 12.6 mg/mL. Furthermore, the absorption and emission properties of this type of oligomers can be easily tuned by incorporating appropriate comonomers. The application of these water-soluble indenofluorene based oligomers as new chemosensors for Hg2+ detection is reported, and the results indicate that these oligomer sensors exhibit a high selectivity and sensitivity for Hg2+ detection without interference from other metal ions.

A highly selective and ratiometric sensor for Hg2+ based on a phosphorescent iridium (III) complex

Abstract A new neutral iridium (III) complex Ir(TBT)2(acac) based on 2-thiophen-2-yl-benzothiazole (TBTH) ligands has been synthesized and characterized. Ir(TBT)2(acac) exhibited color change from red to orange without and with Hg2+, at the same time has a blue shift about 23 nm in fluorescent emission spectra. So it can serve as a highly selective chemodosimeter for Hg2+ with ratiometric and naked-eye detection. The sensor allowed determination of Hg2+ in the working range of 3 μM–10 μM with a detection limit of 2.14 μM. The phosphorescent chemosensor exhibited excellent selectivity and sensitivity for Hg2+ detection.

Sensitive Colorimetric and Fluorescent Detection of Mercury Using Fluorescein Derivations

A colorimetric and fluorometric dual-model probe for mercury (II) ion was developed employing fluorescein hydrazide (FH) in ethanol-HEPES solution (1:1, v/v, pH 8.0). The probe exhibited high selectivity and sensitivity for Hg2+ detection using UV/Vis and fluorescence spectroscopy. Addition of Hg2+ caused a visual color change from colorless to coloured and a fluorescence change from colorless to bright green. Other metal ions did not interfere with the detection of Hg2+.

A new “turn-on” chemodosimeter for Hg2+: ICT fluorophore formation via Hg2+-induced carbaldehyde recovery from 1,3-dithiane

A novel sensitive and specific Hg(2+) chemodosimeter, derived from 1',3'-dithiane-substituted 2,1,3-benzoxadiazole, displays "turn-on" fluorescent and colorimetric responses via an Hg(2+)-triggered aldehyde recovery reaction. Its potential to monitor Hg(2+) in living organisms has been demonstrated using zebrafish larvae.

Highly sensitive, selective, and rapid fluorescence Hg2+ sensor based on DNA duplexes of poly(dT) and graphene oxide

Coupling T base with Hg(2+) to form stable T-Hg(2+)-T complexes represents a new direction in detection of Hg(2+). Here a graphene oxide (GO)-based fluorescence Hg(2+) analysis using DNA duplexes of poly(dT) that allows rapid, sensitive, and selective detection is first reported. The Hg(2+)-induced T(15)-(Hg(2+))(n)-T(15) duplexes make T(15) unable to hybridize with its complementary A(15) labelled with 6'-carboxyfluorescein (FAM-A(15)), which has low fluorescence in the presence of GO. On the contrary, when T(15) hybridizes with FAM-A(15) to form double-stranded DNA because of the absence of Hg(2+), the fluorescence largely remains in the presence of GO. A linear range from 10 nM to 2.0 μM (R(2) = 0.9963) and a detection limit of 0.5 nM for Hg(2+) were obtained under optimal experimental conditions. Other metal ions, such as Al(3+), Ag(+), Ca(2+), Ba(2+), Mg(2+), Zn(2+), Mn(2+), Co(2+), Pb(2+), Ni(2+), Cu(2+), Cd(2+), Cr(3+), Fe(2+), and Fe(3+), had no significant effect on Hg(2+) detection. Moreover, the sensing system was used for the determination of Hg(2+) in river water samples with satisfactory results.