Detection Of Mercury Research Articles

Gold nanoparticles decorated magnetic nanozyme for colorimetric detection of mercury (II) ions via enhanced peroxidase-like activity

Mercury is one of the heavy metal ions that are released to the environment through various means including anthropogenic pollution. A very low dose of mercury in environmental systems such as water can lead to debilitating effects on the health of humans and animals, if consumed untreated. To reduce this effect, it is critical to develop a simple, non-expensive, and non-sophisticated detection and monitoring system of mercury. Here, we report a simple colorimetric method based on the peroxidase-like activity of AuNPs/ZnO/Fe3O4. Different characterization techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and surface-enhanced Raman spectroscopy (SERS) were used to investigate the successful formation of these composites. The formation of AuNPs was assisted by ZnO. The low Km value (0.7368 mM) obtained from the kinetic study of the catalytic oxidation of 3, 3′, 5, 5′ − Tetramethylbenzidine (TMB) showed strong affinity of TMB to AgNPs/ZnO/Fe3O4. The peroxidase-like activity of AgNPs/ZnO/Fe3O4, was further enhanced in the presence of mercury (II). The absorption intensities of the resulting oxidized TMB (oxTMB) increased linearly in a concentration range of 0.05 – 20 µM. The method also exhibited high selectivity to mercury (II) ions. The limit of detection (LOD) in this linear range was found to be 28.1 nM. The feasibility of the method in determination of mercury (II) ions from real samples was confirmed from high recovery rates in tap water samples. The method shows a great potential for determination of mercury (II) ions in environmental samples.

Nitrogen and zinc doped carbon quantum dots for rapid and accurate detection of mercury ions in cosmetics

Rapid and reliable detection technologies for mercury ion in cosmetics are critical for public health. In this study, we synthesized nitrogen and zinc doped carbon quantum dots (N, Zn-CDs) with bright and stable fluorescence using the hydrothermal method. Structure characterization reveals the abundant oxygen- and nitrogen-containing functional groups on the surface of N, Zn-CDs, which readily coordinate with Hg2+, resulting in fluorescence quenching. Basing on this, a rapid and simple quantitative analysis method for Hg2+ detection was designed. By optimizing the detection conditions, a good linear relationship in the range of 0 to 10 μM and a low detection limit of 0.023 μM were achieved. Besides, interference tests demonstrate the presence of other metal ions does not interfere with Hg2+ detection. When detecting Hg2+ in four types of cosmetics spiked with the ion, the sensor achieved recovery rates of 98.27 %, 110.03 %, 100.90 %, and 108.80 %, respectively, with relative standard deviations all under 6.90 %, demonstrating its capability to identify Hg2+ in complex matrices. This research offers a novel approach for the rapid and accurate detection of mercury in cosmetics.

Traceable Calibration of Atmospheric Oxidized Mercury Measurements.

Most previous measurements of oxidized mercury were collected using a method now known to be biased low. In this study, a dual-channel system with an oxidized mercury detection limit of 6-12 pg m-3 was deployed alongside a permeation tube-based automated calibrator at a mountain top site in Steamboat Springs Colorado, USA, in 2021 and 2022. Permeation tubes containing elemental mercury and mercury halides were characterized via an International System of Units (SI)-traceable gravimetric method and gas chromatography/mass spectrometry before deployment in the calibrator. The dual-channel system recovered 97 ± 4 and 100 ± 8% (±standard deviation) of injected elemental mercury and HgBr2, respectively. Total Hg permeation rates and Hg speciation from the gravimetric method, the chromatography system, the dual-channel system, and an independent SI-traceable measurement method performed at the Jožef Stefan Institute laboratory were all comparable within the respective uncertainties of each method. These are the first measurements of oxidized mercury at low environmental concentrations that have been verified against an SI-traceable calibration system in field conditions while sampling ambient air, and they show that accurate, routinely calibrated oxidized mercury measurements are achievable.

Crafting Ultra–Sensitive and selective fluorescent probes for CH3Hg+ detection in groundwater: A 3–in–1 strategy

Development of ultra–sensitive and selective fluorescent probes exclusively targeting CH3Hg+, especially against Hg2+, in real ecosystems like groundwater remains a critical yet formidable challenge. In this contribution, we present a series of fluorescent carbazole boronic acids (probes 1–4) designed for the highly sensitive and selective detection of Hg2+ and CH3Hg+ using an innovative 3–in–1 strategy. Notably, probe 4 exhibited exceptional performance in mercury detection in real groundwater, achieving a limit of detection concentration as low as 1.0 ppb for both Hg2+ and CH3Hg+, even in the presence of elevated levels of interfering cations or anions. Subsequently, a new fluorescent probe system was established by embedding probe 4 into cationic micelles, employing a microphase separation protocol. This resulted in exclusive selectivity towards CH3Hg+ over Hg2+ and other interfering ions with sensitivity as low as 10.0 ppb. This advancement not only addresses a critical gap in environmental monitoring but also demonstrates the potential for broader applications of these probes in sensitive detection methodologies.

Determination of Low Concentrations of Mercury Based on the Electrodeposition Time.

Soil plays a crucial role in human health through its impact on food and habitation. However, it often contains toxic heavy metals, with mercury being particularly hazardous when methylated. Currently, high-sensitivity, rapid detection of mercury is achievable only through electrochemical measurements. These measurements require pretreatment of the soil sample and the preparation of a calibration curve tailored to the sample's condition. In this study, we developed a method to determine the environmental standard value of mercury content in soil by significantly reducing the pretreatment process. Our approach involves analyzing current peaks from electrodeposition times using specific electrodes and solvent settings. This method demonstrates low error rates under low concentration conditions and can detect mercury levels as low as 0.5 ppb in soil leachate and reagent dilution series. This research facilitates the determination of low mercury concentrations in solutions containing various soil micro-compounds without the need for calibration curves.

Photoluminescent Nanocellulosic Film for Selective Hg2+ Ion Detection.

We developed a highly sensitive solid-state sensor for mercury detection by stabilizing red-sub-nanometric fluorescent gold nanoclusters (AuNC, 0.9 ± 0.1 nm diameter) with bovine serum albumin in a matrix composed of cellulose nanofibrils (CNF) (BSA-AuNC/CNF). The main morphological and optical features of the system were investigated via atomic force/transmission electron microscopy and UV-Vis/fluorescence spectroscopy. The hybrid film (off-white and highly transparent) showed strong photoluminescene under UV irradiation. The latter is assigned to the AuNC, which also increase the ductility of the emitting film, which was demonstrated for high sensitivity Hg2+ detection. When used as a sensor system, following AuNC printing on CNF hybrid films, a limit of detection <10 nM was confirmed. What is more, nanocellulose films have a high pore structure and selective separation properties, showcasing a wide range of potential applications in many fields such as water treatment and oil-water separation.

Development of a genetically encoded NMT indicator for detection of mercury ions based on the green fluorescent protein mNeonGreen and metallothionein II from rat liver

Heavy metals, particularly mercury, rank as some of the most hazardous systemic toxicants known to cause multiple organ damage, even at lower levels of exposure. Its detection in the environment and in the live cells is an actual task. Here, we engineered a novel genetically encoded fluorescent NMT indicator for mercury ions by inserting the metallothionein II domain from rat liver into the bright green-yellow fluorescent protein mNeonGreen, followed by directed molecular evolution of the resulting sensor prototype in bacteria. In solution, the NMT indicator was 1.7-fold brighter than the standard eGFP fluorescent protein and responded to the addition of even 10−18-10−19 M mercury ions by quenching fluorescence with a 5-fold fluorescence response and extremely high affinity to mercury ions characterized by the Kd value of 0.50 ± 0.05 aM. We also characterized the selectivity of the NMT indicator to other metal cations. In cultured mammalian cells, the NMT indicator detected even an extracellular concentration of 0.1 fM mercury ions and achieved a 5.9-fold change in ΔF/F fluorescence intensity.

A structure-switching electrochemical aptamer sensor for mercury ions based on an ordered assembled gold nanorods-modified electrode

In this paper, an electrochemical aptamer sensor with high sensitivity and selectivity was proposed for the detection of mercury ion (Hg2+). The ordered assembled gold nanorods-modified screen-printed electrode (AuNRs/SPE) was used to improve the sensor with higher sensitivity and data reproducibility. The sensor was designed based on the specific recognition of Hg2+ with aptamer to form T-Hg2+-T binding structure. Two aptamer chains were applied in the designed sensor, aptamer S1 with terminal thiolate group was self-assembled on the AuNRs/SPE via Au–S bond, and complementary S2 labeled with ferrocene (Fc) would generate a strong redox electrical signal. The addition of Hg2+ would mediate the folding of the T-base of S1 to form a hairpin structure, resulting in the dissociation of the Fc-labeled S2 from the sensing system and a significant reduction in the redox current. The electrochemical properties of the sensor were further investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The effects of aptamer reaction time, concentration, and target incubation time on the sensor response were also investigated. The results showed that the sensor had a sensitive response to Hg2+ at concentrations ranging from 1 pM to 1 μM, with a detection limit of 0.3 pM. Furthermore, the proposed sensor was applied in the determination of Hg2+ in real samples, demonstrating its potential practical value.

A versatile photoelectrochemical biosensor based on in-situ grown 2D COFs film for sensitive detection of Hg2+ and aflatoxin B1

Herein, a highly stable and low-toxic photoelectrochemical (PEC) biosensor was constructed based on two-dimensional covalent organic frameworks (COFs) film composed of tris(4-aminophenyl)amine and 1,4-phthalaldehyde connected through imine bonds (TA-P COFs) was grown in situ on the electrode surface under mild conditions for detecting mercury ion (Hg2+) and aflatoxin B1 (AFB1). Impressively, the TA-P COF film adhered to the electrode surface through in-situ growth not only accelerated the charge transfer between the interfaces, but also improved the stability of the biosensor, further improving the accuracy of detection. Accordingly, when the cyclic amplification process was triggered in the presence Hg2+ to generate a large amount of output DNA, the signal probe with abundant quencher porous carbon hollow spheres s (PCHS) was modified on the electrode surface through the output DNA for the signal “OFF” detection of Hg2+. Meanwhile, due to the specific binding of the target to the aptamer, the released hairpin DNA 2 (H2) signal probe was modified on the electrode surface through base complementary pairing to achieve the signal “ON” detection of AFB1. The suggested multifunction biosensor achieved sensitive detection of Hg2+ in the range of 10 fM–100 nM and AFB1 in the range of 10 fg mL−1–10 ng mL−1, which showed great practical application potential in both environmental and food analysis.

Application of Novel Gill Cell Line from Lates calcarifer for Recognizing Metals Using Probes.

Lates calcarifer (Bloch) is a potential candidate fish species for culture in marine and brackishwater. A continuous gill cell line was derived from L. calcarifer by the explant culture method and has been passaged for 132 times, in Leibovitz's L-15 medium containing 10% fetal bovine serum (FBS) at 28°C. The cells showed a rate of recovery between 90 and 95% after being successfully cryopreserved at various passage levels and formed monolayer in 2-3days without any morphological changes. Immunophenotypic analysis of the SBG cell line revealed that they are of epithelial origin. Polymerase chain reaction assay using mitochondrial 12S rRNA primer specific to L. calcarifer was used to confirm the authenticity of the established gill cell line origin from seabass. The transfection efficiency was evaluated in Seabass Gill (SBG) cell line using pEGFP-N1 and Lipofectamine™ 3000. Transfection efficiency was found to be between 13 and 16%. The cytotoxicity of three different metal detecting probes was evaluated by MTT and Alamar blue assays to determine safe concentration. The result revealed that SBG cell line can be applied for recognition of metals using probes. The current study established, for the first time, a gill-derived cell line (SBG) from Lates calcarifer and its application for the detection of intracellular indium, mercury, and lutetium ions by specific fluorescent probes.

Silver nanoparticles stabilized by nanocellulose as a sensing probe for mercury (II) detection and their response with iron (III) interference

Silver nanoparticles stabilized by nanocellulose as a sensing probe for mercury (II) detection and their response with iron (III) interference

Multi-Emission Carbon Dots Combining Turn-On Sensing and Fluorescence Quenching Exhibit Ultrahigh Selectivity for Mercury in Real Water Samples.

Mercury is a ubiquitous heavy-metal pollutant and poses serious ecological and human-health risks. There is an ever-growing demand for rapid, sensitive, and selective detection of mercury in natural waters, particularly for regions lacking infrastructure specialized for mercury analysis. Here, we show that a sensor based on multi-emission carbon dots (M-CDs) exhibits ultrahigh sensing selectivity toward Hg(II) in complex environmental matrices, tested in the presence of a range of environmentally relevant metal/metalloid ions as well as natural and artificial ligands, using various real water samples. By incorporating structural features of calcein and folic acid that enable tunable emissions, the M-CDs couple an emission enhancement at 432 nm and a simultaneous reduction at 521 nm, with the intensity ratio linearly related to the Hg(II) concentration up to 1200 μg/L, independent of matrix compositions. The M-CDs have a detection limit of 5.6 μg/L, a response time of 1 min, and a spike recovery of 94 ± 3.7%. The intensified emission is attributed to proton transfer and aggregation-induced emission enhancement, whereas the quenching is due to proton and electron transfer. These findings also have important implications for mercury identification in other complex matrices for routine, screening-level food safety and health management practices.

Cellulose-based adsorbent using in mercury detection and removal from water via an efficient grafting strategy of fluorometric sensors by click reaction

Mercury pollution in waters attracts lots of attention due to its serious toxicity and high bioenrichment and many efforts have been devoted in the development of adsorbents for mercury detection and removal. Herein, a cellulose-based adsorbent Cell-TriA-HQ is functionalized with quinoline fluorophore by covalent immobilization through “Click reaction” with high yield. In addition to the admirable adsorptive performance, the prepared adsorbent exhibits excellent selectivity and sensitivity towards Hg (II) in water that the detection limit for Hg (II) is determined to be as low as 1.92 × 10−7 M. The sensitive fluorescence enhancement response is considered to be resulted from the inhibition of photo-induced electron transfer between triazole and quinoline groups and the reinforcement of structural rigidity. The easy manipulation along with excellent performance of adsorption capacity, detective ability and reusability for the multifunctional adsorbent makes it potential in mercury monitoring and removal from aqueous solutions in the field of water treatment.

Ultrasound-assisted synthesis of a Eu3+-functionalized ZnII coordination polymer as a fluorescent dual detection probe for highly sensitive recognition of HgII and L-Cys

A new ZnII coordination polymer (CP) based on 2,3-pyrazine dicarboxylic acid (H2pzdc) and 4,4′-bipyridine (bpy) (ZCP) was synthesized using a facile slow evaporation method. Single-crystal X-ray diffraction revealed that ZCP is a two-dimensional porous CP, [Zn2(pzdc)2(bpy)(H2O)2] n , with van der Waals forces as the dominant interaction within its layers forming a 63 network. Employing energetic ultrasound irradiation, nanoscale ZCP (nZCP) was successfully synthesized and Eu3+ ions were incorporated within its host lattice (Eu@nZCP). The resulting platform exhibits superior fluorescence characteristics and demonstrates notable optical durability. Therefore, it was used as a dual detection fluorescent sensing platform for the detection of mercury and L-cysteine (L-Cys) in aqueous media through a turn-off/on strategy. In the turn-off process, the fluorescence emission of Eu@nZCP progressively quenches by the addition of HgII via a photo-induced electron transfer (PET) mechanism. The fluorescence of Eu@nZCP is quenched to establish a low fluorescence background through the incorporation of HgII. This devised turn-on fluorescent system is suitable for the recognition of L-Cys (based on the strong affinity of L-Cys to the HgII ion) through a quencher detachment mechanism. This method attained a relatively wide linear range, spanning from 0.001 to 25 µM, with the low detection limit of 5 nM for the sensing of HgII. Also, the corresponding limit of detection (LOD) for L-Cys is 8 nM in a relatively wide linear range, spanning from 0.001 to 40 µM.

Direct and Sensitive Detection of Mercury in Soil by Portable Electromagnetic Heating Vaporization and Purge-and-trap Followed by Microplasma Optical Emission Spectrometry

Direct and Sensitive Detection of Mercury in Soil by Portable Electromagnetic Heating Vaporization and Purge-and-trap Followed by Microplasma Optical Emission Spectrometry

Thiourea Functionalised Receptor for Selective Detection of Mercury Ions and its Application in Serum Sample.

A thiourea functionalised fluorescent probe 1-phenyl-3-(pyridin-4-yl)thiourea was synthesized and utilised as a fluorescent turn-on chemosensor for the selective recognition of Hg2+ ion over competitive metal ions including Na+, Mn2+, Li+, Cr2+, Ni2+, Ca2+, Cd2+, Mg2+, K+, Co2+, Cu2+, Zn2+, Al3+ and Fe2+ ions based on the inter-molecular charge transfer (ICT). Intriguingly, the receptor demonstrated unique sensing capabilities for Hg2+ in DMSO: H2O (10:90, v/v). The addition of Hg2+ ions to the sensor resulted in a blue shift in the absorption intensity and also enhancement in fluorescence intensity at 435nm. Fluorescence emission intensity increased linearly with Hg2+ concentration ranging from 0 to 80 µL. The detection limit and binding constant were determined as 0.134 × 10-6M and 1.733 × 107M-1, respectively. The sensing behavior of Hg2+ was further examined using DLS, SEM and FTIR. The probe could detect Hg2+ ions across a wide pH range. Furthermore, the receptor L demonstrated good sensing performance for Hg2+ in bovine serum albumin and actual water samples.

Electrochemical sensing of Pb2+, Cu2+, and Hg2+ by an aminoclay-based porous covalent organic polymer/ multi-walled carbon nanotubes modified glassy carbon electrode

We present a novel electrochemical sensor for the simultaneous detection of Lead (Pb2+), Copper (Cu2+), and Mercury (Hg2+) ions in seafood samples using differential pulse anodic stripping voltammetry (DPASV) technique. The sensor incorporates an aminoclay-based porous covalent organic polymer (AC-PCOP) derived from the polymerization of aminoclay and 1,3,5-benzenetricarboxylic acid (trimesic acid). To enhance conductivity, the AC-PCOP is combined with multi-walled carbon nanotubes (MWCNTs) and utilized for modifying the surface of the glassy carbon electrode (GCE). The AC-PCOP was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and infrared spectroscopy (IR). These analyses confirmed the presence of a hierarchical architecture in the AC-PCOP, which exhibited a spherical shape. The proposed modifier facilitates the deposition-stripping process and electron diffusion between electrolyte and heavy metal ions. Optimized conditions yielded limit of detections (LODs) of 0.0006, 0.0016, and 0.0003 nM, with linear ranges from 0.002 to 1000 nM, 0.005 to 1000 nM, and 0.001 to 1000 nM for Pb2+, Cu2+, and Hg2+, respectively. The sensor successfully measured these ions in seafood samples. Control experiments and validation were performed using cold vapor atomic absorption spectrometry (CVAAS) to determine the ions in the chosen food samples.

A highly stable electrochemical sensor with antifouling and antibacterial capabilities for mercury ion detection in seawater

The monitoring of heavy metal ions in ocean is crucial for environment protection and assessment of seawater quality. However, the detection of heavy metal ions in seawater with electrochemical sensors, especially for long-term monitoring, always faces challenges due to marine biofouling caused by the nonspecific adsorption of microbial and biomolecules. Herein, an electrochemical aptasensor, integrating both antifouling and antibacterial properties, was developed for the detection of Hg2+ in the ocean. In this electrochemical aptasensor, eco-friendly peptides with superior hydrophilicity served as anti-biofouling materials, preventing nonspecific adsorption on the sensing interface, while silver nanoparticles were employed to eliminate bacteria. Subsequently, a ferrocene-modified aptamer was employed for the specific recognition of Hg2+, leveraging the aptamer's ability to fold into a thymine-Hg2+-thymine (T-Hg2+-T) structure upon interaction, and bringing ferrocene nearer to the sensor surface, significantly amplifying the electrochemical response. The prepared electrochemical aptasensor significantly reduced the nonspecific adsorption in seawater while maintaining sensitive electrochemical response. Furthermore, the biosensor exhibited a linear response range of 0.01–100 nM with a detection limit of 2.30 pM, and realized the accurate monitoring of mercury ions in real marine environment. The research results offer new insights into the preparation of marine antifouling sensing devices, and it is expected that sensors with antifouling and antimicrobial capabilities will find broad applications in the monitoring of marine pollutants.

Engineering MOF-derived 2D NPC-TiO2 nanotablet/3D marigold-like ZnIn2S4/CdS nanoparticles dual Z-scheme heterojunction with excellent photoelectric performance: A novel material for sensitive and facile photoelectrochemical sensing detection of mercury ions in aqueous environments by ion-exchange sensing strategy

Herein, a new NH2-MIL-125-derived 2D nitrogen-doped porous carbon-titanium dioxide (NPC-TiO2) nanotablet/3D marigold-like ZnIn2S4/CdS nanoparticles (NPs) dual Z-scheme heterojunction was first exploited for photoelectrochemical (PEC) measurement of mercury ions (Hg2+). Taking NH2-MIL-125 as precursor, the 2D NPC-TiO2 nanotablet was prepared by calcination. The 3D marigold-like ZnIn2S4 and CdS NPs were synthesized by hydrothermal method and aqueous synthesis way, respectively. The acquired NPC-TiO2, ZnIn2S4 and CdS were sequentially modified on the indium tin oxide (ITO) electrode to form the PEC sensing interface by layer-by-layer assembly. Due to the matched band-edge levels, and strong light-harvesting ability, the given heterostructure on ITO electrode generated a large photocurrent. Importantly, it was found that 2D NPC-TiO2 nanotablet/3D marigold-like ZnIn2S4/CdS NPs dual Z-scheme heterojunction could show specifically increased photocurrent signal towards to Hg2+ by employing CdS NPs as Hg2+-recognition probe with selective Cd-to-Hg ion-exchange, resulting from the in-situ formation of the new quaternary NPC-TiO2/ZnIn2S4/CdS/HgS heterostructure to further facilitate the spatial transmission and separation of charges. As a result, Hg2+ was highly sensitively detected with a low detection limit of 20 fM. This PEC sensor was also verified by evaluating Hg2+ in tap water, river water and lake water, demonstrating great application prospect for environment pollutant measurement.

Metal ion-induced multifunctionality in luminescent hydrogels for information encryption and mercury ion detection

Information security has long been a focal point of research. However, the development of cryptographic hydrogels endowed with both high security and multifunctionality remains a challenge. Herein, we reported a method to construct multifunctional hydrogels using a metal ion-induced strategy. Leveraging Au- induced luminescence, Zn2+- induced shape memory, and Hg2+- induced fluorescence quenching, our method engendered a suite of distinctive properties, including fluorescence, shape memory effects, and ionic conductivity. Tunable fluorescence was utilized for detecting Hg2+ with a detection limit as low as 0.0007 μmol/L. Additionally, a successful design of a multilevel information encryption platform, ranging from 2D to 3D, was achieved by combining the aforementioned properties. The information written using Hg2+ as ink can be protected by the fixed shape of Zn2+, and the encrypted information can only be read under the conditions of shape recovery and UV irradiation. This simple yet effective strategy demonstrates a promising future for the application of this hydrogel in information encryption.