Colorimetric Detection Of Mercury Ions Research Articles

Simultaneous generation and immobilization of silver nanoparticles on cellulose membranes by hydrogen bond-assisted in-situ reaction for colorimetric detection of mercury ions and hydrogen peroxide

The present study has verified that silver nanoparticles (AgNPs) can be simultaneously generated and immobilized in the micro-nanopores of regenerated cellulose membranes (CMs) via a simple in-situ synthesis, which can be used for colorimetric detection of mercury ions (Hg2+) and hydrogen peroxide (H2O2). The findings showed that the high-loose interpenetrating porous structure and abundant hydroxyl groups of CMs can serve as both micro-reaction spaces and immobilized sites for the in-situ synthesis of AgNPs. The Ag@CMs, composed of well-dispersed, firmly-fixed, and quantity controlled AgNPs functionalized CMs, have excellent Hg2+ colorimetric detection capabilities with a visual limit of detection (VLOD) as low as 5 nM. It can efficiently complete early-warning and semi-quantitative Hg2+ recognition, and exhibits high storage stability for more than 180 days. Moreover, the Ag@CMs exhibited peroxidase mimic behavior and catalyzed the oxidation reaction of 3,3,5,5-tetramethylbenzidine (TMB) by H2O2 to produce a blue solution. This work proposes a simple “green” approach for the heterogeneous synthesis of controllable and stable AgNPs immobilized on CMs and explores their application in chemosensing.

Rapid Detection of Mercury Ions Using Sustainable Natural Gum-Based Silver Nanoparticles

Fabrication of metal nanostructures using natural products has attracted scientists and researchers due to its renewable and environmentally benign availability. This work has prepared an eco-friendly, low-cost, and rapid colorimetric sensor of silver nanoparticles using tree gum as a reducing and stabilizing agent. Several characterization techniques have been exploited to describe the synthesized nanosensor morphology and optical properties. Ultraviolet−Visible (UV−Vis) spectroscopy has been used for monitoring the localized plasmon surface area. High-resolution transmission electron microscopy (HR-TEM) illustrated the size and shape of silver nanoparticles. X-ray diffraction spectra showed the crystallography and purity of the product. Silver nanoparticles decorated with almond gum molecules (AgNPs@AG) demonstrated high sensitivity and colorimetric detection of mercury ions in water samples. The method is based on the aggregation of AgNPs and the disappearing yellow color of AgNPs via a spectrophotometer. The detection limit of this method was reported to be 0.5 mg/L. This work aimed to synthesize a rapid, easy-preparation, eco-friendly, and efficient naked-eye colorimetric sensor to detect toxic pollutants in aqueous samples.

Selective and sensitive colorimetric detection of mercury ions in aqueous solutions using silver nanoparticles synthesized in innovative biomaterial matrix

Selective and sensitive colorimetric detection of mercury ions in aqueous solutions using silver nanoparticles synthesized in innovative biomaterial matrix

Colorimetric detection of mercury ions from environmental water sample by using 3-(Trimethoxysilyl)propyl methacrylate functionalized Ag NPs-tryptophan nanoconjugate

Recent trend in the nanotechnology made an interest to make nano based system to detect the environmental pollutant including heavy metals, pesticides and antibiotics. Mercury is toxic heavy metals which causes hazardous effect to human and environmental organisms. They usually reach to the environment by mining, petrol refining and coal burning, which can change to its ionic forms according to the environmental condition. The present study was concentrated on the effective detection of Hg (II) ion from environmental sample colorimetrically by developing Ag NPs - tryptophan nanoconjugate functionalized with 3-(Trimethoxysilyl)propyl methacrylate (TMPM). The characterization of prepared particles was performed by UV–visible spectrophotometer, transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), particle size analyzer and zeta sizer. The size of prepared NPs was 9 ± 1.10 nm and it possess the surface charge of −37.41 ± 4 mV. Upon the interaction of Ag NPs - tryptophan nanoconjugate and Hg (II) ion, the colour of the conjugate disappeared. The effect of environmental factors (Temperature, pH and saline concentration) on Hg (II) ion detection was also investigated. The probe indicated that Ag NPs - tryptophan nanoconjugate functionalized with TMPM was found to be an efficient tool for mercury detection from various environmental water samples.

Functionalized Electrospun Nanofibers as Colorimetric Sensory Probe for Mercury Detection: A Review.

Mercury is considered the most hazardous pollutant of aquatic resources; it exerts numerous adverse effects on environmental and human health. To date, significant progress has been made in employing a variety of nanomaterials for the colorimetric detection of mercury ions. Electrospun nanofibers exhibit several beneficial features, including a large surface area, porous nature, and easy functionalization; thus, providing several opportunities to encapsulate a variety of functional materials for sensing applications with enhanced sensitivity and selectivity, and a fast response. In this review, several examples of electrospun nanofiber-based sensing platforms devised by utilizing the two foremost approaches, namely, direct incorporation and surface decoration envisioned for detection of mercury ions are provided. We believe these examples provide sufficient evidence for the potential use and progress of electrospun nanofibers toward colorimetric sensing of mercury ions. Furthermore, the summary of the review is focused on providing an insight into the future directions of designing electrospun nanofiber-based, metal ion colorimetric sensors for practical applications.

Colorimetric Detection of Mercury Ions in Water with Capped Silver Nanoprisms.

The emission of mercury (II) from coal combustion and other industrial processes may have impacts on water resources, and the detection with sensitive but rapid testing methods is desirable for environmental screening. Towards this end, silver nanoprisms were chemically synthesized resulting in a blue reagent solution that transitioned towards red and yellow solutions when exposed to Hg2+ ions at concentrations from 0.5 to 100 µM. A galvanic reduction of Hg2+ onto the surfaces is apparently responsible for a change in nanoprism shape towards spherical nanoparticles, leading to the change in solution color. There were no interferences by other tested mono- and divalent metal cations in solution and pH had minimal influence in the range of 6.5 to 9.8. The silver nanoprism reagent provided a detection limit of approximately 1.5 µM (300 µg/L) for mercury (II), which compared reasonably well with other reported nanoparticle-based techniques. Further optimization may reduce this detection limit, but matrix effects in realistic water samples require further investigation and amelioration.

Colorimetric detection of mercury ions based on anti-aggregation of gold nanoparticles using 3, 5-dimethyl-1-thiocarboxamidepyrazole

A colorimetric method based on the anti-aggregation of gold nanoparticles (AuNPs) for the rapid detection of mercury (II) ions in an aqueous medium is proposed. 3, 5-Dimethyl-1-thiocarboxamidepyrazole (Pzl) was synthesized that caused aggregation of AuNPs and induced a color change from red to blue. However, in the presence of Hg2+, the AuNPs remained in the dispersed state without changing color due to the resilient and preferable interactions between Pzl and mercury ions rather than AuNPs. The change in color of the solution containing AuNPs from red to blue was the consequence of the aggregation mechanism and the presence of mercury ions gave rise to the anti-aggregation mechanism among AuNPs. The sulphur and nitrogen-rich different binding sites of ligand Pzl led to the excellent properties of the signature binding of mercury ions. This admirable property imparted the selective and nanomolar sensitivity of the ligand for mercury ions over the other metal ions. The method can be effectively applied to estimate the mercury level in water samples with good accuracy. The experimental results were also corroborated by Density Functional Theory (DFT) calculations.

Using Gold Nanoparticles with Spectroscopic and Analytical Models for Rapid Colorimetric Detection of Mercury Ions in Aqueous Media

In this study, high-sensitively colorimetric detection of mercury ions was developed according to the surface plasmon resonance of modified gold nanoparticles. While in a citrate buffer solution, the selected modifier Bismuthiol II can cause gold nanoparticles to aggregate. Gold nanoparticles with a spherical shape and average diameter of about 13 nm were prepared. While mercury ions can inhibit gold nanoparticle aggregation, after the addition of mercury ions, the color of the gold nanoparticles solution changes from light violet to red with a hypochromatic shift at the absorption peak. By collecting the UV-Vis spectrum of the solution after the reaction, the characteristic bands are selected to build a partial least squares model. Both the 0.9477 correlation coefficient with a 0.0986 mg/L standard deviation for the calibration set, and 0.9274 correlation coefficient with a 0.1020 mg/L standard deviation for the prediction set were obtained via a partial least squares model.

Synthesis of silver nanoparticles using Matricaria recutita (Babunah) plant extract and its study as mercury ions sensor

Silver (Ag) nanoparticles comprise a highly selective approach for development of nanosensors for the detection of Hg2+ ions. When Ag nanoparticles mixes with Hg2+ ions, loses its UV–Vis absorption intensity. Here, green synthesis of Ag nanoparticles was done using plant extract of Matricaria recutita (Babunah) under ambient conditions. Biosynthesized Ag nanoparticles are well-dispersed having quasi-spherical shape and average particle size of 11nm. XRD, SAED and HRTEM analysis showed that nanoparticles are well crystalline in nature and having cubic phase of geometry. We report here highly selective colorimetric detection of mercury ions (Hg2+) using biosynthesized Ag nanoparticles.

Facile synthesis of bimetallic Ag-Cu nanoparticles for colorimetric detection of mercury ion and catalysis

Here, we reported on a route to the facile synthesis of bimetallic silver doped copper nanoparticles (Ag-Cu NPs) by AgNO3 and CuSO4 in the presence of sodium borohydride and sodium citrate. The present work described the preparation of the Ag-Cu NPs with sodium citrate and the use of them in colorimetric detection of mercury (II) ions. Ag-Cu NPs with an average diameter of 9.0±0.8nm were prepared via two step reduction at room temperature. The Ag-Cu NPs were thoroughly characterized by using UV–vis spectroscopy and transmission electron microscopy (TEM) techniques. The morphology and constitution of the Ag-Cu NPs were characterized by TEM, and the valence state of Ag-Cu NPs was confirmed by the X-ray photoelectron spectroscopic (XPS) result. The synthesized Ag-Cu NPs were yellow in color due to the intense surface plasmon absorption band centered at 406nm. This high selective sensor allowed a direct quantitative assay of mercury ions (Hg2+) with a detection limited of 0.51nM. The synthesized Ag-Cu NPs also exhibited good catalytic activity in two model reactions, the reduction of the nitrophenols and potassium ferricyanide (III) by sodium borohydride.

Gold nanozyme-based paper chip for colorimetric detection of mercury ions

In this study, we developed a facile gold nanozyme-based paper chip (AuNZ-PAD) for Hg2+ detection. This device has the advantages of being simple, rapid, cost effective, sensitive, selective, high throughput, and applicable to onsite detection. The colorimetric mercury assay on the AuNZ-PAD is established based on the enzyme-like catalytic activity of gold nanoparticles promoted by the formation of Au–Hg amalgam, which is correlated to the intensity of the colorimetric response resulting from the catalytic reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2. Highly sensitive and selective detection of Hg2+ ions is achieved in both distilled and tap water samples, indicating the feasibility and applicability of our device for the determination of mercury pollution in real samples. Moreover, AuNZ-PAD analysis using a smartphone camera eliminates the need for expensive analytical equipment, thereby increasing the practicality of field monitoring of trace Hg2+ compared with other sensing methods.

Graphitic carbon nitride supported platinum nanocomposites for rapid and sensitive colorimetric detection of mercury ions

In this study, graphitic carbon nitride supported platinum nanocomposites (g-C3N4/PtNPs) have been synthesized for the first time by an ultrasonic-assisted chemical reduction method. By using g-C3N4 as the stabilizer, Pt ions could be reduced to PtNPs by NaBH4 and uniformly deposited on the surface of g-C3N4. The resulting g-C3N4/PtNPs exhibited enhanced catalytic activity for the oxidation of 3,3′,5,5’-tetramethylbenzidine (TMB) compared to that of g-C3N4 or PtNPs alone. After interaction with Hg2+, the catalytic activity of g-C3N4/PtNPs was effectively inhibited due to the formation of HgPt amalgam. On the basis of this effect, a novel label free colorimetric sensor has been developed for sensitive detection of Hg2+ through the g-C3N4/PtNPs mediated catalytic reaction. A detection limit as low as 1.23 nM was achieved. This assay also exhibited excellent selectivity toward Hg2+ over other metal ions. In addition, it was successfully applied to the determination of Hg2+ in real water samples. In view of the advantages, such as simple operation, cost-effective, rapid response and naked-eye observation, the developed colorimetric sensor hold great potential for the detection of toxic Hg2+ in environmental and biological samples.

Green synthesis of silver nanoparticles using Carica Papaya fruit extract under sunlight irradiation and their colorimetric detection of mercury ions

We have successfully synthesized silver nanoparticles (AgNPs) by using aqueous extract of papaya (Carica papaya) fruit as bioreductant under sunlight irradiation without additional capping agent. Characterizations were done using UV-Visible spectrophotometry and Fourier Transform Infrared Spectroscopy (FTIR). The synthesized AgNPs have yellowish-brown color with surface plasmon resonance peak at 410 nm. Good selectivity of the AgNPs towards hazardous heavy metal of mercury ions in aqueous solution has been developed as a green environmental sensor. The presence of Hg(II) ions in the mixture changed the yellowish-brown color of AgNPs to colorless due to oxidation of Ag(O) in AgNPs to Ag(I) ions. Effect of samples matrix such as alkali metal, alkaline earth metal and transition metal ions were evaluated.

Reliable and reproducible colorimetric detection of mercury ions (Hg2+) using green synthesized optically active silver nanoparticles containing thin film on flexible plastic substrate

Green synthesis of optically active silver nanoparticles (Ag) containing thin film on flexible plastic strip substrate has been carried using guava leaf extract. The properties of silver films were studied using UV–visible spectrophotometer, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) techniques. The silver thin films were used to detect Hg2+ ions in water with lower limit of concentration up to 20 ppm by visually observing the color change of the film from brown to cloudy white. UV–visible spectra indicated blue shift due to strong redox reaction between Ag and Hg2+ ions. Depending upon the time for the color change of the Ag films, the amount of Hg2+ ions in the water is determined. This method is found to be simple and rapid for detection of Hg2+ ions in the solution.

Gold nanoparticle-based colorimetric detection of mercury ion via coordination chemistry

A simple, fast, and convenient colorimetric detection of Hg2+ in aqueous media was presented based on the selective binding capability of thymine derivative (N-T) toward Hg2+. N-T decorated AuNPs solution was stable in red color, while the presence of Hg2+ induces significant aggregation of AuNPs along with red-to-blue color changes. Therefore, Hg2+ content in real water samples can be qualitatively detected by our naked eyes; meanwhile, good linear relationship of Hg2+ along with A650nm/520nm values could be obtained for its quantitative determination. Furthermore, our system shows excellent selectivity to mercury ions against any other tested metal ions and anions, and good sensitivity with LOD of 0.8nM in real water samples.

Colorimetric detection of mercury ions using MnO2 nanorods as enzyme mimics

In this study, a simple and novel “off–on” colorimetric sensor for the detection of mercury ions (Hg2+) in aqueous solution was developed.

Colorimetric detection of mercury ion based on unmodified gold nanoparticles and target-triggered hybridization chain reaction amplification

A novel unmodified gold nanoparticles (AuNPs)-based colorimetric strategy for label-free, specific and sensitive mercury ion (Hg2+) detection was demonstrated by using thymine–Hg2+–thymine (T–Hg2+–T) recognition mechanism and hybridization chain reaction (HCR) amplification strategy. In this protocol, a structure-switching probe (H0) was designed to recognize Hg2+ and then propagated a chain reaction of hybridization events between two other hairpin probes (H1 and H2). In the absence of Hg2+, all hairpin probes could stably coexist in solution, the exposed sticky ends of hairpin probes were capable of stabilizing AuNPs. As a result, salt-induced AuNPs aggregation could be effectively prevented. In the presence of Hg2+, thymine bases of H0 could specifically interact with Hg2+ to form stable T–Hg2+–T complex. Consequently, the hairpin structure of H0 probe was changed. As H1/H2 probes were added, the HCR process could be triggered and nicked double-helixes were formed. Since it was difficult for the formed nicked double-helixes to inhibit salt-induced AuNPs aggregation, a red-to-blue color change was observed in the colloid solution as the salt concentration increased. With the elegant amplification effect of HCR, a detection limit of around 30nM was achieved (S/N=3), which was about 1–2 orders of magnitudes lower than that of previous unmodified AuNPs-based colorimetric methods. By using the T–Hg2+–T recognition mechanism, high selectivity was also obtained. As an unmodified AuNPs-based colorimetric strategy, the system was simple in design, convenient in operation, and eliminated the requirements of separation processes, chemical modifications, and sophisticated instrumentations.

Chitosan-functionalized gold nanoparticles for colorimetric detection of mercury ions based on chelation-induced aggregation

We are presenting a colorimetric assay for mercury (II) ions. It is based on citosan-functionalized gold nanoparticles (AuNPs) that act as a signaling probe. Hg (II) induces the aggregation of the chitosan-AuNPs through a chelation reaction that occurs between chitosan and Hg (II). This results in a strong decrease of the absorbance of the modified AuNPs and a color change from red to blue. This sensing system displays excellent selectivity over other metal ions and a detection limit as low as 1.35 μM which is lower than the allowed level of Hg (II) in drinking water (30 μM) as defined by World Health Organization. The method is inexpensive, facile, sensitive, and does not require the addition of other reagents in order to improving sensitivity.

Highly selective and reversible colorimetric detection of mercury ions by a hydrophilic cycloruthenated complex in water

A new hydrophilic cyclometallated ruthenium complex Ru1-B with 4,4′-dicarboxylate-2,2′-bipyridine (abbreviated as dcbpy) and 2-(2-thienyl)pyridine (abbreviated as thpy) as ligands was successfully synthesized to selectively detect mercury ion in water. Only upon addition of mercury ions, the aqueous solution of the complex exhibits very remarkable color change from red to yellow with a dramatic blue-shift (120nm) of MLCT absorption bands. The detection limit of Hg2+ for this chemo-sensor in HEPES aqueous solution was 0.59μM. Interestingly, the complex can be recovered from complex-Hg2+ both in solution and silica gel plates by adding I−. Therefore, it can be used as a sensitive “naked-eye” indicator for Hg2+ in natural environment.

Mercury Detection: Urine for Plasmonic Nanoparticle‐Based Colorimetric Detection of Mercury Ion (Small 24/2013)

Hundreds of years after the little boy saved his city with urine, X. Chen and co-workers now use urine to detect deleterious ions in a colorimetric assay. As reported on page 4104, the synergetic effect of uric acid and creatinine decorated on gold nanoparticles is the reason for the selective binding of mercury ions, leading to the aggregation of nanoparticles and thereby causing a visual color change. This work inspires the development of the “turning trash into treasure” strategy and the exploitation of natural products in exploring nanotechnology.