Determination Of Hg Research Articles

An Electrochemiluminescence Biosensor for the Determination of Mercury Ion via Dual-Amplification Strategy

A novel dual-signal amplificatory electrochemiluminescence (ECL) deoxyribonucleic acid (DNA) biosensor was designed for the determination of Hg2+. One amplification unit was gold nanoparticles (AuNPs) modified on a glassy carbon electrode, and the other was single-stranded DNA (ssDNA) (with amino at the 3’ terminal and thiol at the 5’ terminal) labeled with a carboxyl-functionalized Ru@SiO2 nanoparticles (Ru1@SiO2) as a nanoprobe. The ECL biosensor was obtained through a strong gold-sulfur bond between Au on AuNPs modified electrode and thiol in the nanoprobe. In the presence of Hg2+, the ECL signal reduced because the T-Hg2+-T existed between the ECL nanoprobe and the complementary DNA (c-DNA), which exhibited a sensing platform for the detection of Hg2+. The results revealed that the reduced ECL intensity was linearly proportional to the logarithm of the Hg2+ concentration in the range of 1.0 pmol L-1-100 nmol L-1 with limit of detection 0.02 pmol L-1. The proposed method was applied for the analysis of Hg2+ in the river water and the results were in good agreement with that obtained by atomic fluorescence spectroscopy.

Aggregation-based determination of mercury(II) using DNA-modified single gold nanoparticle, T-Hg(II)-T interaction, and single-particle ICP-MS.

An ultrasensitive assay is described for the detection and determination of Hg2+(aq) in water samples based on single-particle inductively-coupled plasma/mass spectrometry (spICP-MS). In the presence of Hg2+(aq), AuNPs modified with a segment of single-stranded DNA aggregate due to the formation of the well-known thymine (T)-Hg2+-T complex. Single particle (sp) ICP-MS is used quantify the degree of aggregation by the overall decrease in number of detected AuNPs or NP aggregates. Compared with most other Hg2+ assays that use the same principle of aggregation-dispersion with DNA modified AuNPs, this method has a much lower detection limit of (0.031ngL-1, 155 fM) and a wider (10,000-fold) linear range (up to 1μgL-1). The method also showed good practical potential because of its minimal interference from the water sample matrix. Graphical abstractSchematic representation of Hg2+ determination by using modified AuNP probes measured by spICP-MS. AuNPs pulses detected in ICP-MS is relative to the aggregation status of AuNPs based on thymine-Hg2+-thymine interaction.

Simultaneous detection of lead (II) and mercury (II) ions using nucleic acid aptamer molecular beacons

ABSTRACT We have developed a fluorescence quantitative analysis method for the simultaneous detection of Hg2+ and Pb2+ based on nucleic acid aptamer molecular beacon (MB) probes. In this analytical method, two MB probes for Hg2+ (PHg) and Pb2+ (PPb) were designed. The carboxyl fluorescein (FAM) and tetramethyl-6-carboxyrhodamine (TAMRA) were selected as fluorophores of PHg and PPb, Black Hole Quencher 1 (BHQ-1) and Black Hole Quencher 2 (BHQ-2) were selected as organic quenchers, and several continuous nucleotides with guanine (G base) were connected to organic quenchers. The aptamers are put in as a part of stem and loop. In general, the fluorescence of fluorophores was dually quenched by BHQ and G bases, so the fluorescence signals were weak. In the presence of Hg2+ and Pb2+, PHg and PPb bonded with them, and the stem-loop structure of MB was destroyed and the fluorescence recovered. Under the optimal conditions, the fluorescence intensity of FAM had a good linear relationship with the concentration of Hg2+ in the range from 0.7 nmol/L to 84 nmol/L, and that of TAMRA and Pb2+ in the range from 0.2 nmol/L to 24 nmol/L. The detection limit of Hg2+ is 0.36 nmol/L and that of Pb2+ is 0.16 nmol/L (3σ, n = 11). The relative standard deviations (RSD) for determination of Hg2+ and Pb2+ were both lower than 5%, the average recoveries of this method in real samples were 96.55–102.78%, which indicated that the method had a high accuracy.

Determination of Hg2+ by Diphenylcarbazone Compound in Polymer Film

A sensitive optical sensor for determining Hg2+ concentration has been prepared by incorporating the indicator dye, diphenylcarbazone, into cellulose acetate polymer film. The sensor was fabricated by binding diphenylcarbazone to a cellulose acetate film that had been previously subjected to exhaustive base hydrolysis. The method is easy to perform and uses acetyl cellulose as a carrier. The results showed that the sensor has the ability to determine the Hg2+ concentration with ±6% error. Also, the adsorption capacity was 3.41 × 10-3 mmol/g.

Label-free colorimetric detection of divalent mercuric ions (Hg2+) based on T-Hg2+-T structure and exonuclease III dual-recycling and G-quadruplex-hemin DNAzyme amplification

ABSTRACT Detection of divalent mercury attracts great significance in most biological and environmental systems. In this study, a Thymine-divalent mercuric ions-Thymine (T-Hg2+-T) structure based colorimetric assay with Exonuclease III (Exo III) assisted recycling and G-quadruplex-hemin DNAzyme amplification is put forward for Hg2+ monitoring. The Hg2+ can combine with T-T mismatches of oligo-1 to form T-Hg2+-T base pairs, which brings forth a double-helix structure with a blunt terminus. Short mononucleotide fragment (trigger DNA) and Hg2+ could be released as the double-helix structure in oligo-1 is cleaved by Exo III. The released Hg2+ can be captured by another oligo-1, and generate the new cycles. At the same time, signal DNA (oligo-2) can hybridize with trigger DNA to form double-stranded DNA with a blunt terminus that can be cleaved by Exo III to accrue the trigger DNA and guanine (G)-quadruplex fragment. The trigger DNA can hybridize with another signal DNA, which implements the dual-recycling amplification. The G-quadruplex fragment can form the G-quadruplex-hemin DNAzymes, which can catalyze the oxidation of 2, 2ʹ-azino-bis(3-ethylbenzothiazo-line-6-sulfonate) disodium salt (ABTS2-) by H2O2. The color change, served as the signal output, can be measured with an ultraviolet spectrophotometer. The proposed assay allows Hg2+ to be detected in the range of 25 pM to 2000 pM with a detection limit of 7 pM. Moreover, it has been commendably applied to the determination of Hg2+ in environmental samples and biological samples.

Ultra trace level square wave anodic stripping voltammetric sensing of mercury(II) ions in environmental samples using a Schiff base-modified carbon paste electrode

ABSTRACT In this approach, a new carbon paste electrode modified with N,N′-bis(5-bromo-2-hydroxybenzylidene)-2,2-dimethylpropane-1,3-diamine Schiff base ligand (L) was synthesised for selective and effective determination of Hg2+ ions in aqueous environmental samples using cyclic and square wave anodic stripping voltammetric methods. First, the selective detection of mercury ion was confirmed by evaluating the stability constants of metal complexes formed between the Schiff base ligand (L) and some desired cations by conductometric measurements. Afterwards, by preparing an effective carbon paste electrode modified with L, the experimental and instrumental parameters affecting the performance of modified electrode were investigated. Square wave anodic stripping voltammograms were obtained after applying an accumulation potential −0.5 V and accumulation time 150 s in Britton–Robinson buffer solution at pH 2.0. The optimal square wave parameters found are pulse amplitude 75 mV, frequency 50 Hz and step potential 6 mV. The procedure exhibited linear range from 0.4 to 120 μg L−1 Hg2+ with a limit of detection of 0.042 μg L−1. The proposed electrode was proved to be highly selective in the presence of various cations and anions and was successfully used for determination of mercury in tobacco and several water samples.

Selective Detection of Sub-hundred Picomolar Mercuric Ion in Aqueous Systems by Visible Spectrophotometry Using Gripe Water Functionalized Gold Nanoparticles

A selective and sensitive spectrophotometric determination of Hg2+ was designed based on gripe water functionalized gold nanoparticles (AuNP). Gripe water was employed as both a reducing and a stabilizing agent for the synthesis of gold nanoparticles. The sugar moieties of gripe water were responsible for the reduction of auric ions to Au and the resultant nanoparticles possessing an average particle size of 16 nm were highly stable over a period of 1 year. The gripe water-functionalized gold nanoparticle system was highly sensitive in detecting Hg2+ ions in aqueous medium, with the limit of detection being as low as 0.05 nM. It was also highly selective of mercury even in presence of eleven different commonly associated cations. The efficacy of the nanoparticle sensor system in the analysis of mercury in real-time samples such as bottled, tap, lake and river water has also been evaluated to be good.

Eu3+-Postdoped UIO-66-Type Metal-Organic Framework as a Luminescent Sensor for Hg2+ Detection in Aqueous Media.

Because of its extreme toxicity, the determination of Hg2+ in aqueous solution is an important subject for human health and environmental monitoring. In this study, a novel UIO-66-type metal-organic framework (MOF) doped with Eu3+ (isophthalic acid and 2,6-pyridinedicarboxylic acid and zirconium chloride served as the organic connectors and metal precursor, respectively) was prepared by a hydrothermal method and postsynthetic modification. The obtained lanthanide MOFs exhibited good photothermal and fluorescence stability in aqueous solution. As a luminescent probe, dispersions of the material can specifically recognize Hg2+ in many ions and have a detection limit of 8.26 nM. This novel lanthanide MOF shows great potential applications for biosensing, imaging, environmental analysis, and so on.

Synthesis and Spectral Studies of Schiff Base Receptor for Fluorescence Detection of Hg(II)

In this study, a fluorescent film probe with a structure centered on a Schiff base viz. (N1′,N2′)-N1,N2-bis(2-amino-3,5-dibromobenzylidene)-1,2-diamine (DAB) was synthesized. The probe was used as a fluorescence chemosensor for transition metal ion detection in an aqueous medium. Fluorescence was measured through fluorescence spectroscopy, and the emission maximum of the proposed sensor was 552 nm. Furthermore, the proposed film sensor exhibited a high sensitivity and selectivity toward Hg2+ ions. The limit of detection (LOD) of chemosensor, which was calculated using the fluorescence titration method, found to be 2.11 μM at 552 nm. The fluorescence spectroscopic data evidenced the potential of the proposed sensor for application in the detection and determination of Hg2+ ions in deionized water without the interference from other metal ions.

Pentaethylenehexamine and d-penicillamine co-functionalized graphene quantum dots for fluorescent detection of mercury(II) and glutathione and bioimaging

Pentaethylenehexamine and d-penicillamine co-functionalized graphene quantum dots (PEHA-GQD-DPA) was made via one two-step thermal pyrolysis. The resulting PEHA-GQD-DPA is composed of the graphene sheets with an average size of 3.16 nm and the rich of functional groups. It gives an ultra strong fluorescence emission with the fluorescent quantum yield of 90.91% and sensitive and selective optical response towards Hg2+. The fluorescence intensity linearly decreases with the increase of Hg2+ in the range of 1.0 × 10−10–2 × 10−4 M with the detection limit of 4.6 × 10−11 M (S/N = 3). No species tested interfere with detection of Hg2+. The fluorescence quenched by Hg2+ can be well recovered by glutathione. The fluorescence intensity linearly increases with the increase of glutathione in the range of 5 × 10−8–2.5 × 10−6 M with the detection limit of 1.7 × 10−8 M (S/N = 3). The PEHA-GQD-DPA as a fluorescence probe has been successfully applied in determination of Hg2+ in natural water and glutathione in human serum and SW480 cell imaging.

A Highly Sensitive and Selective Colorimetric Hg2+ Ion Probe Using Gold Nanoparticles Functionalized with Polyethyleneimine.

A highly sensitive and selective colorimetric assay for the detection of Hg2+ ions was developed using gold nanoparticles (AuNPs) conjugated with polyethyleneimine (PEI). The Hg2+ ion coordinates with PEI, decreasing the interparticle distance and inducing aggregation. Time-of-flight secondary ion mass spectrometry showed that the Hg2+ ion was bound to the nitrogen atoms of the PEI in a bidentate manner (N–Hg2+–N), which resulted in a significant color change from light red to violet due to aggregation. Using this PEI-AuNP probe, determination of Hg2+ ion can be achieved by the naked eye and spectrophotometric methods. Pronounced color change of the PEI-AuNPs in the presence of Hg2+ was optimized at pH 7.0, 50°C, and 300 mM·NaCl concentration. The absorption intensity ratio (A700/A514) was correlated with the Hg2+ concentration in the linear range of 0.003–5.0 μM. The limits of detection were measured to be 1.72, 1.80, 2.00, and 1.95 nM for tap water, pond water, tuna fish, and bovine serum, respectively. Owing to its facile and sensitive nature, this assay method for Hg2+ ions can be applied to the analysis of water and biological samples.

Au–Pt–Au nanoraspberry structures used for mercury ion detection

Detection of Hg2+ with high sensitivity is of great significance in the biochemical sensing field. Quantitative of Hg2+ was realized based on the influence of Hg2+ on the UV–vis absorption performance of Au–Pt–Au core-shell nanoraspberry (APA)–rhodamine-6G (R6G) structure. First, APA sol was added into R6G indicator solution and the UV–vis absorption signal intensity of R6G was evidently promoted. The signal intensity monotonously increased as more APA sol was added. However, when HgCl2 solution was introduced, the signal intensity declined. A linear relationship between Hg2+ concentration and signal intensity at 527 nm was revealed, based on which quantitative determination of Hg2+ could be realized. Hg2+ detection sensitivity was measured to be 0.031 a.u./M with a limit of detection of 10-7 M and the response time was 20 s. A high Hg2+ detection selectivity over Cu2+, Na+, Li+, and K+ was demonstrated. Due to its simplicity and high sensitivity, the proposed method could find an extensive application prospect in the Hg2+ detection field.

New pyrrole-based single-molecule multianalyte sensor for Cu2+, Zn2+, and Hg2+ and its AIE activity

An aggregation-induced emission (AIE) active bis-hydrazone in the aqueous medium is designed and prepared, which can be used as a multi-probe that selectively detects Cu2+, Zn2+, and Hg2+ by monitoring the changes in absorption and fluorescence spectral patterns. Results show that Zn2+ and Hg2+ can enhance the fluorescence in EtOH solution. The addition of Cu2+ strongly improves absorption in the visible range. In contrast to the fluorescence of 1 + Zn2+, the fluorescence of 1 + Hg2+ can be maintained in the presence of water. The crystal structure of the Hg(II) complex based on 1 is further determined through X-ray crystallographic analysis. To test the practical use of the probe, the determination of Hg2+ in real water samples was also evaluated.

Determination of Hg2+ Based on the Selective Enhancement of Peroxidase Mimetic Activity of Hollow Porous Gold Nanoparticles

In this paper, a novel colorimetric biosensor for Hg[Formula: see text] is presented based on Hg[Formula: see text] stimulated peroxidase-like activity of hollow porous gold nanoparticles (HPGNPs). Under mild conditions, HPGNPs show high catalytic activity toward the oxidation of 3, 3[Formula: see text], 5, 5[Formula: see text]-tetramethylbenzidine (TMB) using H2O2 as an oxidant. The peroxidase-like activity of HPGNPs is “switched-on” selectively in the presence of Hg[Formula: see text], which permitted a novel and facile colorimetric sensor for Hg[Formula: see text]. This method exhibits many merits like high selectivity and sensitivity. As low as 18.5[Formula: see text]nM Hg[Formula: see text] could be determined at a linear range from [Formula: see text][Formula: see text]M to [Formula: see text][Formula: see text]M. This method is successfully applied for the determination of total mercury content in tap water and Yellow River which indicates that the method has a great potential for the routine determination of Hg[Formula: see text] in environmental samples.

Metal Complexation Properties of Schiff Bases Containing 1,3,5-Triazine Derived from 2-Hydroxy-1-Naphthaldehyde in Solution. A Simple Spectrofluorimetric Method to Determine Mercury (II).

Four new Schiff base ligands carrying naphthalene groups were prepared from the reaction of 2,4-diamino-6-methyl-1,3,5-triazine and 2,4-diamino-6-undecyl-1,3,5-triazine with 2-hydroxy-1-naphthaldehyde. The influence of a series of metal ions including Cu2+, Co2+, Hg2+, Al3+, Cr3+, Fe3+, Pb2+, Ni2+, Cd2+, Zn2+, Mn2+, Ag+, Ba2+, Ca2+ and Mg2+ on the spectroscopic properties of the ligands was investigated by means of absorption and emission spectrometry. The results of spectrophotometric and spectrofluorimetric titrations disclosed the complexation stoichiometry and complex stability constant of the ligands with metal ions. A simple spectrofluorimetric method was developed using the Schiff base derived from 2,4-diamino-6-undecyl-1,3,5-triazine to determine Hg2+ ion. No cleanup or enrichment of the tap water sample was required. A modified standard addition method was used to eliminate matrix effect. The standard addition graph was linear between 0.2 and 2.6mg/L in determination of Hg2+. Detection and quantification limits were 0.08 and 0.23mg/L, respectively. The simple and cost-effective method can be applied to water samples.

Synthesis of Nitrogen-Doped Carbon Quantum Dots and Its Application as Fluorescent Sensor for Hg2+

Compared with traditional quantum dots, carbon quantum dots (CQDs) have aroused tremendous research interest among scientists as new fluorescent carbon nanomaterials due to their unique properties (easy surface functionalization, good biocompatibility, and low toxicity). The nitrogen-doped carbon quantum dots (NCDs) was synthesized with one-step hydrothermal treatment with citric acid as carbon source, and ammonia as nitrogen source. The obtained NCDs exhibited excellent water-solubility and high stability. High-resolution Transmission electron microscopy (HRTEM) image showed that the diameter of particles was about 3nm. Fourier transform infrared (FIIR) and X-ray photoelectron spectroscopy (XPS) spectra analysis demonstrated that the NCDs are functionalized with hydroxyl, amino, carbonyl, and carboxylic acid groups, which indicated NCDs has better water-solubility. It was further demonstrated that such NCDs can serve as effective fluorescent sensing platform for Hg2+ ions detection with sensitivity and selectivity. In a PBS butter solution (0.1 mol·L-1 pH 7.0), the fluorescence quenching ratio (F/F0) indicated linear responses with Hg2+ concentration ranging from 0.001 to 0.1 μmol·L-1, with the detection limit of 2.1 nmol·L-1. The fluorescence technique was superior in terms of sensitivity, selectivity and simplicity. It was successfully applied to determination of Hg2+ in samples.

One-step fabrication of electrochemical biosensor based on DNA-modified three-dimensional reduced graphene oxide and chitosan nanocomposite for highly sensitive detection of Hg(II)

A novel DNA-modified nanocomposite of three-dimensional reduced graphene oxide and chitosan particles (CS@3D-rGO@DNA) was prepared by one-step method and used as a new electrochemical biosensing strategy to detect Hg2+ in drinking water. This biosensor was fabricated by the chemical coordination of T-Hg2+-T between the T-rich oligonucleotide strands contained in the as-prepared CS@3D-rGO@DNA nanocomposite and Hg2+, thereby varying the electrochemical signals. The developed electrochemical biosensor exhibited high sensitivity toward the determination of Hg2+ with a low detection limit of 0.016nM, ranging from 0.1nM to 10nM. This novel biosensor also showed high selectivity, good stability, and repeatability. Hence, this proposed CS@3D-rGO@DNA-based electrochemical strategy is feasible and may offer a simple, rapid, cost-effective, highly selective, and sensitive method for Hg2+ quantification.

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.

Highly sensitive and selective determination of Hg2+ by using 3-((2-(1H-benzo[d]imidazol-2-yl)phenylimino)methyl)benzene-1,2-diol as fluorescent chemosensor and its application in real water sample

A new receptor 3-((2-(1H-benzo[d]imidazol-2-yl)phenylimino)methyl)benzene-1,2-diol (1) was synthesised and developed as a highly selective fluorescent chemosensor for the detection of Hg2+ in semi-aqueous media. The fluorescence of receptor 1 was dramatically and selectively quenched on complexation with Hg2+ ion with the detection limit down to 0.20 μM. The developed sensor was successfully applied for the determination of Hg2+ content in water samples. Density Functional Theory (DFT) calculations were performed to study the mechanistic behaviour behind the binding of Hg2+ with receptor 1.

Selective Extraction and Detection of Hg2+ in Aqueous Solution by using Rhodamine Dye-Modified Silica Gel

Novel silica gel-immobilized rhodamine (SGR) anchored by hydrazinium hydrate was synthesized. The selectivity and adsorption ability of the SGR for metal cations were investigated with fluorophotometry and atomic absorption spectrophotometery, respectively. The SGR exhibits high selectivity and adsorption capacity for Hg2+. The maximum static adsorption capacity of the SGR for Hg2+ was 25.8 μmol g−1. The linear response range covers a concentration range of Hg2+ from 20 ppb to 2000 ppb and the detection limit is 10 ppb. The determination of Hg2+ in real water samples displays satisfactory results, and the SGR can be used repeatedly by treating with a solution of tetrabutylammonium hydroxide.