Sensitive Detection Of Mercury Ions Research Articles

Post-synthetic modification on metal organic frameworks composite for efficient removal and sensitive detection of mercury ions in water

Post-synthetic modification (PSM) technique is employed on the optimization of metal organic frameworks (MOFs) composites. In this work, a new Zr-MOF derived from UiO-66 is prepared and used as efficient adsorbents for mercury removal from water and able to detect mercury ions with excellent selectivity. It is observed that the fluorescence intensity of UiO-66-An exhibits good linearity across the concentration range of 0.5–2.5 μM and the detection limit of mercury is calculated to be as low as 2.67 × 10-8 M which is below the effluent standard declared by WHO. Furthermore, the removal efficiency of UiO-66-An for Hg (II) can still maintain 64.8 % after 5 cycles of adsorption–desorption process. In addition, the adsorption capacity of the adsorbent is determined to be as high as 303.03 mg/g for mercury, indicating the successful integration of adsorptive and detective functions together on a single adsorbent material which is beneficial for practical application in mercury management.

Portable smartphone-assisted highly sensitive detection of mercury ions based on gold nanoparticle-modified NH2-UiO-66 metal-organic framework.

A novel portable smartphone-assisted colorimetric method was reported for the determination of Hg2+ with good analytical performance. AZr(IV)-based metal-organic framework functionalized with amino groups(NH2-UiO-66) has been adopted as asupporting platform to anchor gold nanoparticles (AuNPs), avoiding the migration and aggregation of AuNPs. With the addition of Hg2+, the formation of gold amalgam proved possible to enhance peroxidase-like activity of the composite (AuNPs/NH2-UiO-66), accelerating the oxidization of zymolyte 3,3',5,5'-tetramethylbenzidine (TMB). In the meantime, the color of the reaction solution turned a vivid blue, and the red, green, and blue (RGB) values of the solution color changed accordingly. On account of this strategy, the quantitative detection of Hg2+ could be achieved. After the optimization of the experiment conditions, the average color intensity (Ic) resulting from RGB values was linear related to the concentration of Hg2+ from 10 to 100nM, accompanied with a detection limit (LOD) down to 5.4nM calculated by 3σ/S. The successful application of the designed method has been promoted to detect Hg2+ in some water samples, displaying a great potential in practical application. Furthermore, the use of a smartphone made our proposed method simple and accurate, and thus puts forward a possible way for in situ and real-time monitoring.

Photoelectrochemical biosensor with Au@PTCA Schottky junction and multiple sandwich structures for Hg2+ sensitive detection

Herein, a novel photoelectrochemical (PEC) biosensor was built on the strength of gold nanoparticles@3,4,9,10-Perylene tetracarboxylic (Au@PTCA) Schottky junction and multiple sandwich structures caused by thymine-Hg2+-thymine (T-Hg2+-T) and base complementary pairing, realizing the highly sensitive detection of mercury ion (Hg2+). The proposed Au@PTCA Schottky junction was formed by using PTCA as carrier and Au NPs as signal enhancer, which could significantly improve photoelectric conversion efficiency, resulting in a strong initial PEC signal. The multiple sandwich structures possessed high steric hindrance effect, which could directly block external electron supply and light harvesting, giving rise to a significantly quenched PEC signal. In addition, the execution of the multiple sandwich structures could extinguish initial PEC signal produced by Au@PTCA Schottky junction, acquiring the comparison of various PEC signals, thereby fulfilling the quantitative detection of Hg2+. The experimental results showed that the PEC signal was gradually suppressed as the Hg2+ concentration increased in the range of 10 pM to 10 μM and the detection limit was 3.33 pM under optimal conditions, giving the sensor the advantages of high selectivity and excellent stability. This study demonstrated a promising method for sensitive detection of Hg2+ and offered a valuable approach with potential applications in environmental detection, biological analysis, and medical research.

Spectrofluorometric detection of mercury ions in aqueous medium and cellular milieu using MoS2 nanoflakes

This communication reports the facile hydrothermal synthesis of fluorescent two-dimensional layered MoS2 nanoflakes using a biomolecule (l-cysteine) for efficient and sensitive detection of mercury ions (Hg2+) in aqueous solution by monitoring the fluorescence quenching of MoS2 in a ratiometric approach. This fluorescence quenching of MoS2 was successfully utilized to detect Hg2+ ions in both normal (H9c2 cell line) and cancer (A549 cell line) cells as well via fluorescence imaging microscopy. The as-synthesized MoS2 nanostructured sample was characterized using UV–vis absorption, steady-state fluorescence emission, X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. The strong fluorescence emission of nanostructured MoS2 was heavily quenched by Hg2+ ions in aqueous medium as confirmed by fluorescence spectroscopic results. The binding of Hg2+ with MoS2 nanoflakes and the resulting fluorescence quenching were also supported by Stern–Volmer analysis. The selectivity and sensitivity of the interaction of Hg2+ ions with the as-prepared MoS2 nanoflakes among all other interfering metal ions were analyzed. The selective interaction of Hg2+ with MoS2 was also accompanied by a distinct color change from bluish-green to flaxen or pale yellowish-gray in aqueous medium. The limit of detection of Hg2+ ions in aqueous medium was 0.63 nM. The possible interactions between Hg2+ and MoS2 were confirmed by Fourier transform infrared spectroscopy, time-resolved fluorescence, and cyclic voltammetry studies. Density functional theoretical calculations provided useful information to correlate the electronic structure and energy band distributions with the spectroscopic results for the interaction of Hg2+ with MoS2 nanoflakes. The MoS2 nanoflakes showed no significant cytotoxicity during their interaction with Hg2+ ions in the intracellular medium, as confirmed by MTT assay, thereby ensuring possible future biomedical applications.

Facile and sensitive detection of mercury ions based on fluorescent structure-switching aptamer probe and exonuclease Ⅲ-assisted signal amplification

Hg2+ is highly toxic to human health and ecosystem. In this work, based on the unique fluorescent property of 2-Aminopurine (2-AP), the formation of T-Hg2+-T mismatch structure and the signal amplification of exonuclease III (Exo III) assisted target cycle, a fluorescent probe for facile and sensitive detection of Hg2+ is constructed. The hairpin-looped DNA probe is rationally designed with 2-AP embedded in the stem and thymine-rich recognition overhangs extended at the termini. The cleavage of the double stranded DNA stem with stable T-Hg2+-T pairs catalyzed by Exo III is prompted to happen upon recognition of trace Hg2+. Under the optimal reaction conditions, there is an excellent linear relationship between Hg2+ concentration and fluorescence intensity in the range of 7.5–200 nM with a detection limit of 0.38 nM. In addition, the detection results of Hg2+ in Songhua River water and fish samples are satisfactory. The fluorescent probe avoids labeling additional quenchers or quenching materials and has strong anti-interference ability. Thus, the fluorescent probe has a broad prospect in practical application.

Folic Acid Adjustive Polydopamine Organic Nanoparticles Based Fluorescent Probe for the Selective Detection of Mercury Ions.

Polydopamine fluorescent organic nanomaterials present unique physicochemical and biological properties, which have great potential application in bio-imaging and chemical sensors. Here, folic acid (FA) adjustive polydopamine (PDA) fluorescent organic nanoparticles (FA-PDA FONs) were prepared by a facile one-pot self-polymerization strategy using dopamine (DA) and FA as precursors under mild conditions. The as-prepared FA-PDA FONs had an average size of 1.9 ± 0.3 nm in diameter with great aqueous dispersibility, and the FA-PDA FONs solution exhibit intense blue fluorescence under 365 nm UV lamp, and the quantum yield is ~8.27%. The FA-PDA FONs could be stable in a relatively wide pH range and high ionic strength salt solution, and the fluorescence intensities are constant. More importantly, here we developed a method for rapidly selective and sensitive detection of mercury ions (Hg2+) within 10 s using FA-PDA FONs based probe, the fluorescence intensities of FA-PDA FONs presented a great linear relationship to Hg2+ concentration, the linear range and limit of detection (LOD) were 0-18 µM and 0.18 µM, respectively. Furthermore, the feasibility of the developed Hg2+ sensor was verified by determination of Hg2+ in mineral water and tap water samples with satisfactory results.

Au NP-Decorated g-C3N4-Based Photoelectochemical Biosensor for Sensitive Mercury Ions Analysis.

Herein, an efficient and feasible photoelectrochemical (PEC) biosensor based on gold nanoparticle-decorated graphitic-like carbon nitride (Au NPs@g-C3N4) with excellent photoelectric performance was designed for the highly sensitive detection of mercury ions (Hg2+) . The proposed Au NPs@g-C3N4 was first modified on the surface of the electrode, which possessed a remarkable photocurrent conversion efficiency and could produce a strong initial photocurrent. Then, the thymine-rich DNA (S1) was immobilized on the surface of the modified electrode via Au–N bonds. Subsequently, 1-hexanethiol (HT) was added to the resultant electrode to block nonspecific binding sites. Finally, the target Hg2+ was incubated on the surface of the modified glassy carbon electrode (GCE). In the presence of target Hg2+, the thymine–Hg2+–thymine (T-Hg2+-T) structure formed due to the selective capture capability of thymine base pairs toward Hg2+, resulting in the significantly decrease of the photocurrent. Thereafter, the proposed PEC biosensor was successfully used for sensitive Hg2+ detection, as it possessed a wide linear range from 1 pM to 1000 nM with a low detection limit of 0.33 pM. Importantly, this study demonstrates a new method of detecting Hg2+ and provides a promising platform for the detection of other heavy metal ions of interest.

Heterostructured nanochannels with modulated ionic current rectification for ultrasensitive detection of Hg2+

A sensor with heterostructured nanochannels consisting of a porous Nafion membrane and a DNA functionalized AAO membrane was designed for the sensitive detection of mercury ions with LOD of 1 pM due to the change of rectified ionic currents.

Wood-derived nanocellulose hydrogel incorporating gold nanoclusters using in situ multistep reactions for efficient sorption and sensitive detection of mercury ion

A wood-derived nanocellulose hydrogel (WNH) with gold nanoclusters (Au NCs) was prepared by in situ multistep reactions, which was used as an effective adsorbent for the adsorption of mercury ion (Hg2+) and a solid-state fluorescent probe for detecting Hg2+. The WNH’s morphology, chemical structure and optical properties were investigated. The adsorption performance of WNH towards the Hg2+ ion was studied, indicating that the sorption data were well fitted by Langmuir and pseudo-second-order models with a maximum sorption capacity of 234.4 mg/g. The detection performance of WNH towards the Hg2+ ion was also investigated, showing excellent selectivity and sensitivity to Hg2+ with a detection limit of 0.09 μg/L. The 3D porous structure created by wood-derived nanocellulose increased adsorption and detection, according to the mechanism analysis. Furthermore, a cost analysis was performed for WNH and commercial activated carbon, and the results showed that WNH was the economically viable option for Hg2+ sorption. This research could pave the way for a low-cost, multi-functional and environmentally friendly mercury adsorbent.

A novel polymeric hybrid sensory smart material for the prompt recognition of mercury ions in water

An acrylamide-xanthene hybrid polymeric probe was synthesized for the selective and sensitive detection of mercury ions (Hg2+) in 100% water. The non-polymeric form of probe displayed extraordinary selectivity above other additional metal cations via both a visual color change and fluorescence change with exceptional reversibility and responds rapidly to changes in the environment. The 1H NMR titration study revealed the binding of an Hg2+ ion on the imine hydrogen of the probe by the opening of the spiro-lactam ring, which instigates an instant color change. Reversible behavior of the polymeric probe using an aqueous solution of EDTA was confirmed by both absorption and fluorescence studies. The prepared polymeric probe detects Hg2+ in 100% water and is a promising material for the mercury recognition in real-time.

Novel fluorescent nanocellulose hydrogel based on gold nanoclusters for the effective adsorption and sensitive detection of mercury ions

Mercury is a major pollutant of water. An efficient adsorbent for mercury ions is urgently needed. In this study, we developed a novel fluorescent nanocellulose hydrogel (NH) based on cellulose nanocrystals and gold nanoclusters with high adsorption ability (maximum adsorption capacity: 95.7 mg/g for Hg(II)) and high detection sensitivity and selectivity for Hg(II). The chemical structure, physical structure, and Hg(II) adsorption and detection characteristics of novel NH were characterized. Moreover, the mechanism analysis confirmed that cellulose nanocrystals provided a natural skeleton to construct the three-dimensional (3D) porous structure for accelerating Hg(II) adsorption and provided chemical functional groups to increase the number of effective sorption sites for improving Hg(II) adsorption capacity; gold nanoclusters wrapped in the 3D porous structure of the NH served not only as a fluorescent probe for a visual response for Hg(II), but also as sorption sites facilitating the adsorption of Hg(II) ions. Owing to these factors, the novel NH has considerable potential for use in the removal of Hg(II) ions from wastewater.

Fluorescence enhancement of CdSe/ZnS quantum dots induced by mercury ions and its applications to the on-site sensitive detection of mercury ions.

The significant fluorescence enhancement of CdSe/ZnS quantum dots (QDs) induced by Hg2+ was observed for the first time based on a CdSe/ZnS QD-modified fiber nanoprobe. The fluorescence enhancement mechanism contributed to the Zn-to-Hg cation exchange in the ZnS shell, which allowed to form a HgxZn1-xS/CdSe heterojunction and increase the separation of electrons and holes and reduce the recombination rate. High concentrations of Hg2+ accelerated the generation of thefluorescence signal and lead to higherfluorescence intensity. The maximum fluorescence intensity increased more than eight times when Hg2+ concentration was 1µM.The characteristic time (θc), i.e.,the rising time to achievethe maximum fluorescence intensity, was linearly dependent on initial concentration of Hg2+ solution in accordance withour proposed theory. When the evanescent wave optofluidic fluorescence platform was used, the linear detection range and detection limit of Hg2+ were 5.0-1000nM and 0.80nM, respectively. The fiber nanoprobe can be applied to the rapid, sensitive, and accurate on-site detection of Hg2+ in real water samples without significant matrix effect. Our work paves a novel way to develop a simple and reliable nanoprobe for mercuric pollution control, and achieve the high quantum efficiency of QDs by limiting the diffusion of Hg2+ in the ZnS shell.

Aggregation-induced chemiluminescence system for sensitive detection of mercury ions.

As mercury ions (Hg2+) are emanated to surroundings in the course of various natural events and human activities, an accurate sensing of Hg2+ is essential for human health and environmental protection. Herein, a new aggregation-induced chemiluminescence (CL) sensor for fast, sensitive, and selective detection of Hg2+ is developed, based on the CL enhancement ofbis(2,4,6-trichlorophenyl)oxalate (TCPO)-H2O2 system by thiolate-protected gold complexes (Au(I)-thiolate complexes) in the aggregated state. Because Hg2+ has a strong interaction with hydrosulfuryl (-SH) groups in Au(I)-thiolate complexes, the aggregation is disrupted and the CL is quenched. The decrease of CL intensity is proportional to Hg2+ contents with a linear range of 0.005-10μgmL-1and the limit of detection (LOD) is 3ngmL-1. To the best of our knowledge, this is the first AIE CL sensor for Hg2+ detection. The study opens up attractive perspectives for developing simple and rapid aggregation-induced CL methods in monitoring heavy metals.

Fabrication of an artificial ionic gate inspired by mercury-resistant bacteria for simple and sensitive detection of mercury ion

Bioremediation of mercury pollution by mercury-resistant bacteria requires the key steps of mercury ions (Hg2+) capture and transportation. Inspired by the functions of mercury transporters in mercury-resistant bacteria, we have fabricated an artificial ionic gate, which may further behave as an Hg2+ biosensor. The gate is constructed by using the asymmetrically modified porous anodic alumina (PAA) film capable of forming Hg2+-activated complexes to control ionic current, while the gate works due to the changes between graphene oxide (GO) and different DNA structures. Specifically, single strand poly(T)n DNA on PAA film may transform into duplex structure through T-Hg2+-T coordination chemistry when Hg2+ exists. Compared with the ring by ring delivery via S-Hg intermediates in bacteria, this artificial gate may show better flexibility for Hg2+ transport, because the poly(T)n-Hg2+ complex can be wrapped in a chain structure with controllable DNA length. Furthermore, with the advantages of simple structure, convenient operation and good practicality, the constructed artificial Hg2+-activated ionic gate has been developed as a biosensor for sensitive detection of Hg2+, with the limit of detection (LOD) down to 0.07 fM. The fabricated ionic gate may be used for building an instrument that can absorb and detect Hg2+ from wastewater in the future.

Electrochemical aptamer sensor for highly sensitive detection of mercury ion with Au/Pt@carbon nanofiber‐modified electrode

AbstractIn this paper, an electrochemical aptamer sensor was proposed for the highly sensitive detection of mercury ion (Hg2+). Carbon nanofiber (CNF) was prepared by electrospinning and high‐temperature carbonization, which was used for the loading of platinum nanoparticles (PtNPs) by the hydrothermal method. The Pt@CNF nanocomposite was modified on the surface of carbon ionic liquid electrode (CILE) to obtain Pt@CNF/CILE, which was further decorated by gold nanoparticles (AuNPs) through electrodeposition to get Au/Pt@CNF/CILE. Self‐assembling of the thiol‐based aptamer was further realized by the formation of Au‐S bond to get an electrochemical aptamer sensor (Aptamer/Au/Pt@CNF/CILE). Due to the specific binding of aptamer probe to Hg2+ with the formation of T‐Hg2+‐T structure, a highly sensitive quantitative detection of Hg2+ could be achieved by recording the changes of current signal after reacting with Hg2+ within the concentration range from 1.0 × 10−15 mol/L to 1.0 × 10−6 mol/L and the detection limit of 3.33 × 10−16 mol/L (3σ). Real water samples were successfully analyzed by this method.

Highly Sensitive Detection of Mercury Ions Using Zincophosphite Framework Nanoparticle–Polyaniline Composites

This study reports a highly sensitive mercury ion sensor composed of the zincophosphite framework nanoparticle (NTOU4nano) blended with in situ synthesized conductive polyaniline (PANI). High stabi...

Novel nitrogen-doped carbon dots prepared under microwave-irradiation for highly sensitive detection of mercury ions

In this paper, new nitrogen doped carbon dots with a high quantum yield and novel optical properties were synthesized by a simple and fast one step microwave-assisted synthesis. Citric acid monohydrate was used as a carbon source and 2,2-dimethyl-1,3-propanediamine as nitrogen source. The prepared N-CDs were characterized by Fourier transform infrared, Raman, UV-visible and photoluminescence spectroscopies. Transmission electron microscope (TEM) images revealed that the N-CDs have distinctive flake-shape morphology. The N-CDs exhibit bright blue luminescence and quenching response towards Hg2+ ions. The quenching sensitivity was investigated. The results indicate a limit of detection as low as 7.63 nM and a linear relationship over the range 0–4.2 μM. In addition, the prepared N-CDs were tested as sensor for pH in the range from 1 to 7.

An electrochemiluminescence sensor based on CdSe@CdS-functionalized MoS2 and a GOD-labeled DNA probe for the sensitive detection of Hg(ii)

In this study, a novel electrochemiluminescence (ECL) biosensor based on a CdSe@CdS quantum dot (QD)-functionalized MoS2-modified electrode was developed for the sensitive detection of mercury ions.

Electrochemical aptasensor based on Au@HS-rGO and thymine-Hg2+-thymine structure for sensitive detection of mercury ion

A sensitive electrochemical aptasensor was prepared on the basis of gold modified thiol reduced graphene (Au@HS-rGO) and thymine-Hg2+-thymine (T-Hg2+-T) constitution for the checkout of Hg2+. Firstly, Au@HS-rGO was fabricated as the substrate onto the glassy carbon electrode (GCE) surface, which facilitated the subsequent introduction of single-stranded DNA onto the electrode. Following that, thionine (Th) was immobilized on the electrode surface depend on the physical size effect of T and Hg2+. Finally, the amount of Hg2+ was determined by differential pulse voltammetry (DPV) of Th. Under the best conditions, the linear range of the aptasensor to Hg2+ was in the range of 1–200nmol/L and the detection limit was as low as 0.38nmol/L. Simultaneously, good selectivity and acceptable reproducibility were revealed in the designed aptasensor. Moreover, the design thought may provide an idea for the detection of other substances in the water sample.

Dandelion-like CuO microspheres decorated with Au nanoparticle modified biosensor for Hg2+ detection using a T-Hg2+-T triggered hybridization chain reaction amplification strategy

We fabricate a novel electrochemical biosensor based on the specific thymine-Hg2+-thymine (T-Hg2+-T) base pair for the highly sensitive detection of mercury ions (Hg2+) and utilize toluidine blue (TB) as a redox indicator that is combined with a hybridization chain reaction (HCR) for signal amplification. The dandelion-like CuO (D-CuO) microspheres that were assembled using Au nanoparticles were first introduced as support materials, which produced more active sites for the thiolated probe (P1) combination. Then, the presence of Hg2+ induced P1 to hybridize with the other oligonucleotide (P2) through Hg2+-mediated T-Hg2+-T complexes. In addition, the partial sequence of P2 acted as an initiator sequence, which led the two hairpin DNA (H1 and H2) strands to collectively form the extended double-strand DNA through the HCR process on the electrode surface. TB was employed to interact with the double strands and produce an efficient electrochemical signal. The proposed strategy combined the amplification of the HCR and the inherent redox activity of TB and utilized D-CuO/Au composites, which exhibited high sensitivity for Hg2+ determination. Under the optimum conditions, the proposed biosensor showed a prominent response for Hg2+, including a linear range from 1 pM to 100 nM and a detection limit of 0.2 pM (S/N = 3). Moreover, the new biosensor proved its potential application for trace Hg2+ determination in environmental water samples.