Detection Of Mercury Research Articles

Indirect detection of lead(II), cadmium(II) and mercury(II) on a microfluidic electrophoresis chip.

Water environments contaminated by heavy metal ions present significant challenges because these pollutants do not degrade naturally, leading to their gradual bioaccumulation in animals and plants, which ultimately poses an insurmountable threat to human health. Therefore, rapid and accurate detection of heavy metal ions in water is of great significance for environmental protection and disease prevention. In this work, we developed a novel method based on microfluidic electrophoresis coupled with indirect chemiluminescence for the immediate detection of Cd(II), Pb(II) and Hg(II) heavy metal ions. The displacement of the Co(II) ions within the chemiluminescence mixture by the above migrating sample cations caused a measurable reduction in the background signal. The results showed that the detection limits of Cd(II), Pb(II) and Hg(II) ions under the best detection conditions were 5.83 × 10-8 M, 5.38 × 10-8 M and 2.09 × 10-8 M, respectively, which were 1-2 orders of magnitude lower than those of the indirect UV method and 1 order of magnitude lower than that of the indirect laser induced detection method. This method can provide a possibility for the rapid detection of multiple heavy metal ions in actual water environments.

Biocompatibility evaluation and imaging application of a new fluorescent chemodosimeter for the specific detection of mercury ions in environmental and biological samples

Mercury is widely distributed in the natural environment and living environment, and as a heavy metal element with significant toxicity mercury ions pose a threat to agriculture and the food chain, thus consequently the residue and bioaccumulation of mercury ions will cause numerous and serious diseases, such as neurological abnormalities, gingivitis and tremor. Therefore, the development of a responsive and accurate fluorescent probe or sensor with excellent biocompatibility for mercury ions is crucial and marketable in the health and environmental protection. In this study, a novel fluorescent probe named BE-Hg has been innovatively proposed for the dynamic monitor of mercury ions. The probe showed excellent spectral performance in vitro experiments with detection limit as low as 1.18 nM, while it was applied to monitor environmental water samples with recovery as high as 93 %. Moreover, our group evaluated the probe safety using fluorescence-labeled tissue, organ and organ system including liver, heart, blood vessel and immune system in zebrafish for the first time. Note that the probe is proved with good biocompatibility by the cytotoxicity test, behavioral test, hepatotoxicity test, cardiotoxicity test, blood vessel toxicity test and immunotoxicity test with 15 indicators. In addition, the probe owns the ability to detect Hg2+ in live cells and zebrafish models. Thus it is expected to be a tool for the detection of mercury ions in water environments and organisms. In addition, behavioral test, hepatotoxicity test, cardiotoxicity test, blood vessel toxicity test and immunotoxicity test can be used to evaluate the biocompatibility of fluorescent probe, which provide a reliable safeguard for the research and development of probe.

An Automated Cell-Free Workflow for Transcription Factor Engineering.

The design and optimization of metabolic pathways, genetic systems, and engineered proteins rely on high-throughput assays to streamline design-build-test-learn cycles. However, assay development is a time-consuming and laborious process. Here, we create a generalizable approach for the tailored optimization of automated cell-free gene expression (CFE)-based workflows, which offers distinct advantages over in vivo assays in reaction flexibility, control, and time to data. Centered around designing highly accurate and precise transfers on the Echo Acoustic Liquid Handler, we introduce pilot assays and validation strategies for each stage of protocol development. We then demonstrate the efficacy of our platform by engineering transcription factor-based biosensors. As a model, we rapidly generate and assay libraries of 127 MerR and 134 CadR transcription factor variants in 3682 unique CFE reactions in less than 48 h to improve limit of detection, selectivity, and dynamic range for mercury and cadmium detection. This was achieved by assessing a panel of ligand conditions for sensitivity (to 0.1, 1, 10 μM Hg and 0, 1, 10, 100 μM Cd for MerR and CadR, respectively) and selectivity (against Ag, As, Cd, Co, Cu, Hg, Ni, Pb, and Zn). We anticipate that our Echo-based, cell-free approach can be used to accelerate multiple design workflows in synthetic biology.

Reusable fluorescence nanoprobe based on DNA-functionalized metal-organic framework for ratiometric detection of mercury (II) ions.

Areusable fluorescent nanoprobewas developedusing DNA-functionalized metal-organic framework (MOF) for ratiometric detection of Hg2+. We utilized a zirconium-based MOF (UiO-66) to encapsulate tris(bipyridine) ruthenium(II) chloride (Ru(bpy)32+), resulting in Ru(bpy)32+@UiO-66 (RU) with red fluorescence. The unsaturated metal sites in UiO-66 facilitate the attachment of thymine-rich single-strand DNA (T-ssDNA) through Zr-O-P bond, producing T-ssDNA-functionalized RU complex (RUT). The T-ssDNA selectively binds to Hg2+, forming stable T-Hg2+-T base pairs and folding into double-stranded DNA, which permits the intercalation of SYBR Green I (SGI) and activates its green fluorescence. In the presence of Hg2+, SGI fluorescence increases in a dose-dependent manner, while Ru(bpy)32+ fluorescence remains constant. This fluorescence contrast enables RUT to serve as an effective ratiometric nanoprobe for Hg2+ detection, with a detection limit of 3.37 nM. Additionally, RUT demonstrates exceptional reusability due to the ability of cysteine to remove Hg2+, given its stronger affinity for thiol groups. The RUT was successfully applied to detect Hg2+ in real water samples. This work advances the development of ratiometric fluorescence nanoprobe based on DNA-functionalized MOFs.

Electrochemical/fluorescent dual-mode aptasensor based on 3D porous AuNPs/MXene for detection of ultra-trace mercury (Hg2+)

In this work, the dual-mode aptasensor based on 3D porous AuNPs/MXene using “turn-on” electrochemical method and “turn-off” fluorescent strategy was fabricated. Here, 2D MXene was processed into 3D porous MXene by sacrificial polymethylmethacrylate (PMMA) spherical template. And the meteor hammer-like AuNPs which had good electrochemical properties and quenching effect on fluorescence was synthesized by single electrodeposition. Dual-signal labeled Nile Blue (NB) was in situ grafted to the Hg2+ aptamer ends of 3D porous AuNPs/MXene/GCE, and an efficient and sensitive signal interface was constructed to realize the sensitive detection of Hg2+. 3D porous AuNPs/MXene had the advantages of large specific surface area, excellent electron transmission performance and signal amplification. The experimental results indicated that this sensor exhibited high sensitivity to Hg2+ in both electrochemical and fluorescent sensing, with detection limits of 2.69 fM and 1.60 fM, respectively. Further, the dual-mode aptasensor can ensure the detection accuracy and target quantization. The dual-mode aptasensor has been successfully applied to the ultra-trace detection of Hg2+ in actual water samples, which shows the potential of aptamer sensor in detecting heavy metal ions in environmental monitoring.

Immobilization of cobalt phthalocyanine-imbedded electrospun nanofibers on a gold electrode for the electrocatalytic detection of mercury(II)

This research study describes the nanofabrication of electrospun nanofibers (ENFs) containing a coumarin tetra-substituted cobalt phthalocyanine (CoPc-cou), polyaniline (PANI) and polyvinyl alcohol (PVA). This nanocomposite was used to modify a gold substrate which was followed by the immobilisation of a 5 % Nafion (Nf) solution affording the CoPc-cou-ENFs-Nf|Au modified electrode. Comparison of the chemically modified electrode (CME) with the bare and other modified electrodes shows that the CME under optimised conditions displayed superior detection of Hg(II) attaining a linear range of 10 – 3000 µM. Furthermore, the CME exhibits selectivity and sensitivity in an interference sample containing multiple heavy metals. A good percentage recovery of 96 % was attained when the CoPc-cou-ENFs-Nf|Au electrode was applied to a real water sample which was comparable to a percentage recovery of 98 % which was attained using the ICP-OES to analyse the same water samples.

Z-scheme heterostructure of ZnO@NPC/Au/ZnIn2S4 for chemical replacement reaction-mediated signal-on photoelectrochemical assay of mercury ion

Herein, an advanced Zn-based metal organic framework (Zn-MOF) derived ZnO embedded in a nitrogen-doped porous carbon (ZnO@NPC) polyhedron/Au/ three-dimensional (3D) chrysanthemum-like ZnIn2S Z-scheme heterojunction was employed for the chemical replacement reaction-mediated signal-on photoelectrochemical (PEC) sensing detection of mercury ions (Hg2+). The p-type ZnO@NPC polyhedron was initially prepared by carbonising the zeolitic imidazolate framework (ZIF)-8 polyhedron, followed by modification with Au nanoparticles (NPs) via an in situ photocatalytic reduction method. Subsequently, the ZnO@NPC/Au polyhedron was combined with n-type 3D chrysanthemum-like ZnIn2S4 through physical adsorption, forming the ZnO@NPC polyhedron/Au/3D chrysanthemum-like ZnIn2S4 Z-scheme heterostructure. The newly constructed heterostructure exhibited strong visible light–harvesting capacity, and considerably improved photoelectric conversion efficiency. The 3D chrysanthemum-like ZnIn2S4 functioned not only as a photosensitiser but also as an Hg2+ recognition probe. Importantly, the PEC sensor exhibited a considerably increased photocurrent response to Hg2+. This is presumably because the introduction of Hg2+ triggered a selective Zn-to-Hg chemical replacement reaction, leading to the in-situ formation of a ZnO@NPC/Au/ZnIn2S4/HgS heterojunction, which further improved charge separation. Consequently, Hg2+ was sensitively detected with a wide linear range from 0.5 pM to 2 μM and a low detection limit of 0.07 pM. Furthermore, the proposed sensor was validated by detecting Hg2+ in food and aqueous environments, indicating its potential application in food safety and environmental monitoring.

Modification of Screen Printed Carbon Electrode-Gold Nanoparticles (SPCE-AuNPs) for Detection of Mercury in Cosmetics

The cosmetics industry in Indonesia has experienced a significant increase of 12.6% from 2022 to June 2023, with 1025 industries having a positive impact on the Indonesian economy. Apart from that, it has triggered a number of naughty manufacturers to use dangerous chemicals in their cosmetic products such as mercury (Hg). Therefore, it is important to develop a fast and sensitive method for detecting mercury in cosmetics using SPCE-AuNPs. This research was carried out by synthesizing gold nanoparticles (AuNPs) using the reducing agent sodium citrate (Na3H5C6O7) with varying concentrations and characterization of several chemical instruments. Furthermore, SPCE was modified by AuNPs, its performance and application were tested to detect mercury in cosmetic cream using cyclic voltammetry (CV). SPCE-AuNPs provides an electrochemical response with higher oxidation and reduction peaks than bare SPCE with an oxidation peak at a potential of 0.1 V to 0.3 V and a reduction peak at -0.05 V to 0.05 V at a scan rate of 0.01 V/s to 0.03 V/s. This shows a good electrochemical response so it can be used for application to detection of mercury in cosmetic samples. The SPCE modified using AuNPs can potentially be used as a sensor for mercury detection in cosmetics.

Smartphone-enabled composite of cellulose nanocrystals for rapid and selective mercury detection in cosmetics and water: insights from density functional theory studies

ABSTRACT The pervasive contamination of cosmetics and water with mercury ions (Hg(II)) poses severe health risks, driving the need for efficient methods for in situ detection and removal of it. Our study showcases a groundbreaking composite material that combines cellulose nanocrystals (CNCs) and smartphones for the purpose of rapid and selective mercury detection. The CNCs exhibit a distinctive rod-like morphology, presenting a high surface area that facilitates the accommodation of the Hg(II) ion probe, 4-(dimethylamino)phenyl)methanethione (DPM). This interaction leads to a distinct colour change from yellow to green, visible to the naked eye, enabling straightforward visual detection. Our composite is highly sensitive, with a limit of detection (LOD) of 1.76 × 10 − 8 M using digital image analysis and 3.6 × 10 − 8 M using spectrophotometric methods. These values are significantly below the safe drinking water guidelines set by the World Health Organization (WHO). Density functional theory (DFT) calculations were used to understand how Hg(II) ions interact with the DPM-CNC composite. These calculations confirmed that the material has a strong affinity for Hg(II) ions and demonstrated its selective detection capabilities. The DPM-CNC composite’s low detection threshold, rapid response time, and ease of regeneration make it a potent candidate for practical applications in mercury monitoring. This composite is a robust and reusable solution for real-time visualisation and quantification of mercury ions. It only requires 10 mg of material for effective measurements. It enhances safety in cosmetic products and water.

Harnessing biomass derived carbon material with heteroatoms for sensitive and selective detection of mercury (II) ions in waste water

A wide range of raw materials can be converted into carbon materialsprimarily through chemical and physical activation, or a combination of both. The characteristics of resultant carbon material depend significantly on activation method and the specific raw materials used. This work processes date seed biomass using a chemical activation and thermal annealing method to derive a low-cost and porous carbon material DS-AC@400. The material was then used as a fluorescent sensing probe for selective and precise detection of Hg2+ ions in wastewater. There was a linear correlation between Hg2+ concentration and fluorescence intensity of DS-AC@400 with a limit of detection of 8.69 nM. It was found that the DS-AC@400-based fluorescent sensor has a high selectivity for Hg2+ detection against other interferingmetal ions. The sensor workedeffectively in real water samplesfor practical applications with little interference from interfering ions.

Metabolic engineering-enabled dual-color biosensor for discriminative and sensitive detection of toxic lead and mercury in environmental waters

The ubiquity of toxic heavy metals, particularly lead (Pb) and mercury (Hg), in environmental waters severely threatens ecosystems and human health. We developed a metabolic engineering-based dual-color bacterial biosensor for the sensitive and discriminative detection of Pb(II) and Hg(II) at nanomolar levels. The biosensor leverages the synthetic biology approach to integrate two pigments, prodeoxyviolacein (PDV) and deoxyviolacein (DV), into a single construct that responds distinctly to Pb(II) and Hg(II), respectively. The engineered E. coli biosensor exhibits a detection range of 0.732–3000 nM for Pb(II) and 0.183–750 nM for Hg(II), with low detection limits of 0.732 nM for Pb(II) and 0.183 nM for Hg(II). The biosensor demonstrated high sensitivity, selectivity, and accuracy with a recovery rate close to 1 in freshwater and seawater matrices. Notably, the biosensor's visual readout allows for rapid, equipment-free assessment. It is a practical tool for real-world monitoring of heavy metal pollution, especially in remote or resource-limited settings. This study underscores the potential of whole-cell biosensors as a sustainable and effective alternative to traditional heavy metal detection methods.

Nitrogen-doped carbon quantum dots (NCQDs) detected to mercury ions in food monitoring

Using 2,3-diaminopyridine and citric acid as precursors, blue fluorescent nitrogen-doped carbon quantum dots (NCQDs) with a narrow size distribution (∼7.2 nm) were prepared and applied in the following assay for mercury ion detection at a weight ratio of 2,3-diaminopyridine:citric acid = 1:1 (0.2 g: 0.2 g, 20 mL for H2O), 220 °C, and 10 h. NCQDs was characterized by TEM, FT-IR, XPS, UV–Vis and EDS, and the prepared NCQDs display excitation-independent behavior due to less surface defects and uniform size. The optimal excitation and emission wavelengths of the NCQDs were 380 nm and 430 nm, respectively. Interestingly, the fluorescence of the NCQDs could be rapidly and selectively quenched by Hg2+ within 9 min at room temperature without further modification. Under optimal conditions, the limit of detection (LOD) was measured to be at the nanomolar level (42.4 nmol/L) with a linear range of 0–5.0 μmol/L, and fluorescence analysis of NCQDs was successfully used for the qualitative and quantitative analysis of mercury ions in food samples. Furthermore, our results revealed that fluorescence quenching occurred under the common fluences of the inner filter effect, and the static quenching effect was authenticated in the process in which Hg2+ coordinates with the NCQDs to form nonfluorescent complexes.

A smartphone sensing fluorescent detection of mercury ion based on silicon quantum dots in environment water

Mercury ion (Hg2+) pose a significant hazard to the natural environment. Conventional techniques like Inductively coupled plasma mass spectrometry, X-ray absorption spectroscopy, among others, pose some disadvantages as they demand a lot of money, need trained employees, and cannot provide on-site detection in real-time. A smartphone sensing technique based on silicon quantum dots (Si-QDs) was presented to detect Hg2+ in the environment without the usage of sophisticated equipment. Meanwhile, the technology was built by utilizing a smartphone to capture gray values of fluorescent images of the Si-QDs-Hg2+ system. Microwave-assisted Si-QDs with tiny particle size, high fluorescence, and good optical stability were created. The fluorescence of the Si-QDs was gradually quenched by raising the Hg2+ concentration from 0.5 μmol/L to 5.0 μmol/L for fluorescent detection with a detection limit of 28 nmol/L. The 94.8–97.1 % recovery demonstrated the viability of the Si-QDs approach for detecting Hg2+. Meanwhile, a smartphone sensing strategy was built by recording the gray value of the fluorescent images of the Si-QDs-Hg2+ systems using a smartphone, and the detection limit of the established approach was 3 nmol/L. The accuracy and reliability of the smartphone strategy were verified with the recovery rates of 80.3–92.5 % in tap water and 87.6–109 % in river water. Electron transfer quenching mechanism between Si-QDs and Hg2+ was evidenced by ultraviolet–visible spectroscopy, fluorescent decay curves, cyclic voltammetry, and Zeta potential. Finally, the suggested approach was used to detect Hg2+ in water samples from various environments.

Enhanced peroxidase-like activity based on electron transfer between platinum nanoparticles and Ti3C2TX MXene nanoribbons coupled smartphone-assisted hydrogel platform for detecting mercury ions

BackgroundHeavy metal pollution poses a serious threat to the ecological environment. Mercury ion (Hg2+) is a class of highly toxic heavy metal ions, which is bioaccumulative, difficult to breakdown, and has a significant affinity with sulfur and thiol-containing proteins, which seriously affects environmental safety and human health. Nanozyme-based sensing methods are expected to be used to detect toxic heavy metal ions. However, the application of precious metal nanozymes to develop portable sensors with simplicity, high stability, and high sensitivity has not been explored to a large extent. ResultsIn this paper, based on MXene's unique adsorption capacity for certain precious metal ions, PtNPs/Ti3C2TXNR composites were successfully prepared by in-situ growth of Pt nanoparticles (PtNPs) on the surface of Ti3C2TX MXene nanoribbons (Ti3C2TXNR) using the hydrothermal technique. Experimental data revealed PtNPs/Ti3C2TXNR exhibited superior peroxidase-like activity, attributed to the synergistic effect of well-dispersed ultrasmall PtNPs and electron transfer effect. Hg2+ can significantly inhibit enzyme-like activity of PtNPs/Ti3C2TXNR due to specific capture and partial in-situ reduction of PtNPs, so a colorimetric sensor was constructed for ultra-trace detection of Hg2+ with a linear range of 0.2 nM and 400 nM. Furthermore, using the portable detecting capabilities of smartphones and hydrogel, a smartphone-assisted hydrogel sensing platform of Hg2+ was constructed. Notably, the two-mode sensing platforms exhibited outstanding detection performance with LOD values as low as 15 pM (colorimetric) and 26 pM (hydrogel), respectively, superior to recently reported nanozyme-based Hg2+ sensors. SignificanceCompared with other methods, the PtNPs/Ti3C2TXNR-based dual-mode sensor designed in this paper has superior sensitivity, high selectivity, simple operation and portability. In particular, the dual-output sensing strategy enables self-confirmation of detection results, greatly improving the reliability of the sensor, and is expected to be used for the on-site determination of trace mercury ions.

Smartphone-enabled mesoporous silica nanotube chemosensors for quick and selective mercury detection in water and cosmetics

The pervasive presence of mercury in water and cosmetics poses significant health risks, necessitating the development of a method for the in-situ monitoring and extraction of mercury ions. This study introduces a novel approach utilizing Mesoporous Silica Nanotubes (MSNTs) with a unique worm-like structure, providing an expansive surface area ideal for the adsorption of a Hg2+ ion chromophore, N,N,N,N′-Tetramethyl-4,4′-diaminobenzophenone. This configuration enables rapid and visible detection of toxic mercury, with a color transition from yellow to green that is easily discernible by the naked eye. The sensitivity of the Mercury nano-sensor (MNS) is remarkably high, with a detection limit of 1.9 × 10-8 M as determined by digital image analysis, and 4.9 × 10-8 M via spectrophotometric methods—both well below the WHO guidelines for drinking water. The MNS’s low detection threshold, coupled with its reusability after simple regeneration, positions it as an effective tool for preliminary water testing. The findings suggest that the MNS, requiring only 10 mg for measurements, offers a promising solution for the real-time visualization of mercury ions, enhancing safety measures in water and cosmetic products.

A rapid response optical fiber sensor with highly selective probe for trace detection of mercury (II) ions

A highly sensitive, selective, and well-repeatable optical fiber sensor was proposed for trace measurement of Hg2+ concentration in the water environment based on Mach-Zehnder interference. The proposed structure was prepared by splicing a piece of thin core fiber (TCF) between multimode fibers (MMF) to form MMF-TCF-MMF. A novel sensitive film 3-mercaptopropyl-trimethoxysilane (MPTMS) modified polyvinyl alcohol (PVA) has been designed and synthesized, and uniformly coated on the surface of TCF. The specific combination of Hg2+ with PVA-MPTMS sensitive film can change the effective refractive index of the coating mode, enabling the measurement of Hg2+ concentration by tracking the interference spectra. The results show that the sensitivity of the PVA-MPTMS-coated sensor can achieve 17.5 nm/μM with a detection limit of 3.42 nM in the concentration range of 0–1000 nM. The sensor represents excellent repeatability and stability and a rapid response time of roughly 90 s. Meanwhile, the proposed sensor shows a specific recognition of Hg2+ and is unaffected by many other interfering metal ions in the water, which corresponds well with the binding energy calculated by the density functional theory (DFT). The sensor for Hg2+ detection exhibits compact structure, rapid response, high selectivity and repeatability, showing promising potential applications in the field of environmental monitoring.

Electrochemiluminescence detection of Hg2+ using lanthanide mental organic gel based on boric acid functionalization

Recent advancements in electrochemiluminescence (ECL) have highlighted the potential of metal–organic gels (MOGs) as innovative luminescent materials for environmental monitoring. This study introduces a terbium-based Metal–Organic Gel (Tb-MOG) synthesized through a straightforward solvothermal method, exhibiting quantitative detection of mercury ions (Hg2+). The high mesoporosity of Tb-MOG facilitates co-reactant penetration and the gel does not come off easily when applied to the electrodes, enhancing the stability and efficiency of ECL signals. The organic ligand 5-borophenyl-1,3-dicarboxylic acid (5-bop) serves dual functions: it sensitizes Tb3+ luminescence and specifically recognizes Hg2+. Upon the interaction with Hg2+, the boronic acid group of 5-bop undergoes a metal transfer reaction, resulting in an enhanced ’antenna’ effect, which enhances ECL emission. The linear range for Hg2+ of the proposed method was from 1.2 μM to 24.6 μM, with a detection of limit (LOD) of 0.53 μM.

Detecting dissolved mercury(ii) ions using chitosan-AgNP strips integrated with smartphones.

A simple preparation of a paper strip test with a smartphone-based instrument for detecting dissolved mercury is still in development. This study aims to develop a smartphone-based colorimetric paper strip test using chitosan-stabilized silver nanoparticles for detecting dissolved mercury. The method demonstrated high sensitivity and selectivity for Hg2+ ions, with detection limits comparable to UV-vis spectrophotometry. Silver ions embedded in the chitosan matrix were reduced by either sodium NaBH4 or N2H4. Both chi-AgNP colloidal and chi-AgNP paper strips were tested for sensitivity of mercury(ii) solution detection with and without ion interference. The accuracy of colour change responding to the mercury concentration was recorded with several smartphones in a handmade cubical and a T-shape micro-studio. Only NaBH4 gives colloidal chi-AgNPs relatively dispersed, and the colloidal chi-AgNPs become aggregated when AgNP interacts with mercury(ii) ions. The colour change of chi-AgNP paper strips responding to the concentration of mercury(ii) and quantified using a smartphone is consistent when confirmed with UV-vis spectrophotometric determination with a comparable limit of detection (0.76 μM). The inferring ions do not significantly affect mercury(ii) analyses. Therefore, the paper strip integrated with the smartphone is effectively used for mercury(ii) detection in water as long as the mercury concentration is >1 μM. This finding might inspire advanced technology with a larger number of data references, and machine learning involvement to develop more compatible and simple mercury detection.

Facile Preparation of Tannic Acid-Gold Nanoparticles for Catalytic and Selective Detection of Mercury(II) and Iron(II) Ions in the Environmental Water Samples and Commercial Iron Supplement.

Tannic acid (TA), a plant-derived polyphenol rich in hydroxyl groups, serves as both a reducing agent and stabilizer for synthesizing gold nanoparticles (TA-AuNPs). This study presents a groundbreaking method that utilizes TA to fabricate TA-AuNPs and develop two distinct colorimetric detection systems for mercury (Hg2+) and iron (Fe2+) ions. The first detection system leverages the interaction between TA-AuNPs and Hg2+ to enhance the peroxidase-like activity of TA-AuNPs, facilitating the production of hydroxyl radicals upon reaction with hydrogen peroxide, which subsequently oxidizes 3,3',5,5'-tetramethylbenzidine (TMB) into a blue-colored product (ox-TMB). The second system capitalizes on TA-AuNPs to catalyze the Fenton reaction between Fe2+ and hydrogen peroxide in the presence of 2, 6-pyridinedicarboxylic acid, boosting the generation of hydroxyl radicals that oxidize TMB into a blue-colored ox-TMB. Absorbance measurements at 650 nm display a linear relationship with Hg2+ concentrations ranging from 0.40 to 0.60 μM (R2 = 0.99) and Fe2+ concentrations from 0.25 to 2.0 μM (R2 = 0.98). The established detection limits for Hg2+ and Fe2+ are 18 nM and 96 nM, respectively. Applications to real-world samples achieved an excellent spiked recovery, spanning 101.6% to 108.0% for Hg2+ and 90.0% to 112.5% for Fe2+, demonstrating the method's superior simplicity, speed, and cost-effectiveness for environmental monitoring of these ions compared to existing techniques.

Chemical speciation of methylmercury and mercury(II) cations in fish by new fluorogenic naphthalimide alkynyl gold complexes: The ultimate test for detecting fish contamination

The proof of concept of a new portable protocol for the detection and speciation of methylmercury and mercury(II) cations in fish samples is described. In this way, traces of methylmercury and/or mercury(II) cations in fish were quantitatively detected using an elaborated protocol and including a fluorescent sensor. In-the-field accurate results were obtained due to the selective behavior of the chemical sensor in the presence of both cations, working at very low concentrations of mercury species in fish under standard laboratory conditions, that are suitable for daily use in ordinary sampling by border companies importing fish or remote laboratories where large devices cannot be carried. The reported fish protocol is useful under real-life conditions for analyzing fish for the presence of methylmercury in contrast to total mercury analysis. The combination of the protocol and the fluorescent reporter constitutes the ultimate test for fish contamination by mercury(II) species in the workplace. The reported limits of detection of 0.72 nM for Hg2+ and 1.62 nM for CH3Hg+ and the closely related values of the two mercury(II) species in fish samples, obtained by ICP-MS analysis and fluorescent measurements, make the method suitable for daily control of methylmercury in fish under the EU legislation parameters and the WHO recommendations.