Mercury Ions Research Articles

Novel fluorescent sensor based on triazole-pyridine derivative for selective detection of mercury (II) ions in different real water samples: Experimental and DFT calculations

Toxic heavy metals, particularly mercury II ions, must be selectively detected in industrial effluent to restrict their percentage and thereby aid in environmental protection. The present study describes the synthesis of 6-(4-(4-(5-cyano-6-oxo-4-styryl)-1,6-dihydropyridin-2-yl)-5-methyl-1H-1,2,3-triazol-1-yl)phenyl)-2-oxo-4-styryl)-1,2-dihydropyridine-3-carbonitrile (TOHC) and its ability as a novel selective fluorescent probe for the detection of mercury II ions in different real water samples. The structure of the prepared TOHC was confirmed by both FTIR and 1HNMR analysis, while crystal structure and thermal stability was investigated using XRD and TGA techniques. The optical properties of TOHC were investigated using both UV–vis and fluorescence spectroscopy at different pH values. Its luminescent properties obtained when TOHC is excited by a wavelength equal to 424 nm, where a maximum emission peak has observed at a wavelength equal to 466.6 nm. Moreover, using Stern-Volmer equation indicate that there is a good correlation between the concentration of Hg2+ ions and the fluorescence intensity of TOHC accompanied with high quenching rate equal to 2.24 x 104 mol−1.L. Selectivity of TOHC toward Hg2+ ions was confirmed by the assistance of fifteen different metal cations. In addition, Job’s Plot method and UV–vis spectroscopy were used to estimate the stoichiometry as well as understand the quenching mechanism between TOHC sensor and Hg2+ ions. The applicability of TOHC sensor for the detection of Hg2+ ions in real samples was further validated using five different real water samples and exhibited excellent results. Lastly, DFT calculations were conducted to provide atomistic insights into the chemical interaction between Hg(II) and TOHC.

Nanocellulose-stabilized nanocomposites for effective Hg(II) removal and detection: a comprehensive review.

Mercury pollution, with India ranked as the world's second-largest emitter, poses a critical environmental and public health challenge and underscores the need for rigorous research and effective mitigation strategies. Nanocellulose is derived from cellulose, the most abundant natural polymer on earth, and stands out as an excellent choice for mercury ion remediation due to its remarkable adsorption capacity, which is attributed to its high specific surface area and abundant functional groups, enabling efficient Hg(II) ion removal from contaminated water sources. This review paper investigates the compelling potential of nanocellulose as a scavenging tool for Hg(II) ion contamination. The comprehensive examination encompasses the fundamental attributes of nanocellulose, its diverse fabrication techniques, and the innovative development methods of nanocellulose-based nanocomposites. The paper further delves into the mechanisms that underlie Hg removal using nanocellulose, as well as the integration of nanocellulose in Hg detection methodologies, and also acknowledges the substantial challenges that lie ahead. This review aims to pave the way for sustainable solutions in mitigating Hg contamination using nanocellulose-based nanocomposites to address the global context of this environmental concern.

Insight into the synthesis and mechanism of oxacalix[4]arene based nanohybrids for dual readout sensing and removal of Hg2+ ions

Mercury contamination has been a major concern for decades and its removal from environment and natural waterbodies are of highest priority. Inspired by the fact to detect trace amount of mercury and consequently removal of the same, here we present a silver nanoparticle based affordable, rapid and sensitive probe for inspecting the mercury levels on various waterbodies and soil samples with exceptional sensitivity (12 nM). This study reports the design, synthesis and characterization of novel disulfonic acid functionalized oxacalix[4]arene appended silver nanoparticles (DSOC@AgNPs). Driven by the distinct color change phenomena of DSOC@AgNPs upon interaction with Hg2+ ions, we have fabricated a paper strip-based ready-to-use detection kit for rapid detection of mercury ions up to sub-nanomolar concentration. Moreover, DSOC@AgNPs modified screen-printed carbon electrodes (SPCE) have been developed and utilized as a rapid detection kit for mercury in environmental samples. DSOC@AgNPs encapsulated ZIF-8 nanohybrid (DSOC@AgNPs-ZIF) have been employed for the removal of Hg2+ ions from mercury contaminated wastewater with a removal efficiency of 95%. Incidentally, this is the first report for the removal of Hg2+ ions (CH3Hg+ and Hg2+ species) using oxacalixarene-stabilized AgNPs. Further, the surface-modified Rh6G-DSOC@AgNPs reveal its bio-imaging potentiality for mercury detection in living systems and also exhibited dose-dependent cytotoxicity against MCF-7 cells, with an IC50 value of 354.62 μM.

Ion‐imprinted thiosalicylichydrazide‐based sorbents for selective recognition of mercury (II) ions

AbstractBackgroundThe study of removing heavy metals from water through the use of chelating absorbents is an emerging and critical area of research. However, the challenge lies in the lack of specificity that these absorbents often exhibit towards individual metals.ResultsIn addressing this challenge, we have synthesized a novel chelating polymer, thiosalicylic hydrazidine‐modified poly(acrylonitrile‐co‐divinylbenzene) copolymer (TSH‐P), demonstrating a high affinity for Hg2+ ions. The cross‐linking of the Hg2+/TSH‐P complex with a glyoxal cross‐linking agent effectively encapsulates Hg2+ ions, stabilizing the functional chelating groups within the coordination geometry of Hg2+. The ions were subsequently removed with EDTA/HNO3, producing a sorbent imprinted with Hg2+ ions (Hg‐IIP). Analytical techniques such as FTIR, NMR, XPS, and SEM were employed for a detailed examination of each synthesis step, confirming the successful chelation of Hg2+. Notably, the synthesized Hg‐IIP showed significant selectivity for Hg2+ over other metal cations, with an optimal absorption pH of 5 and a maximum capacity of 350 mg/g. The adsorption process was found to closely follow the Langmuir isotherm model, with kinetics that adhered to the pseudo‐second‐order model.ConclusionThis study introduces a highly selective chelating polymer for the removal of Hg2+ ions from water, highlighting its effectiveness and potential for specificity in heavy metal remediation. The use of analytical techniques to confirm the successful synthesis and chelation process, alongside the demonstrated selectivity and high capacity of the sorbent, underscores the polymer's utility in addressing the challenge of removing heavy metals from aqueous solutions.This article is protected by copyright. All rights reserved.

Polysulfide-ene polymerization of bisacrylamides and bismaleimides toward sulphur-rich polymers

Given the ever-increasing importance of developing more sustainable solutions for the fabrication and engineering of polymeric materials, alternative building blocks to the petroleum-derived chemicals are gaining growing interest. In addition to its natural abundance, elemental sulfur is produced industrially in vast quantities which is primarily obtained as a side product from oil refineries and gas purification plants. Thus, elemental sulfur has been prospected as a sustainable resource for the fabrication of structurally diverse polymers. In this study an efficient methodology to obtain sulfur-rich polymers from elemental sulfur-derived polysulfide salts is reported. Polysulfide-ene step growth polymerization of bisacrylamide and bismaleimide-based monomers with bifunctional disodium pentasulfide (Na2S5) generated structurally diverse polyamide and polyimide copolymers incorporating polysulfide chains on the polymer backbones. Copolymers up to 31.8 kDa molecular weight (Mn) and 94% monomerconversions were efficiently obtained under ambient temperature conditions and without the need of any metal or organo-catalyst. By choosing various bifunctional ene monomers, structurally diverse and tailorable linear copolymers were obtained. The methodology was also extended to the fabrication of sulfur-rich crosslinked polymers by employing a multifunctional thiolate-based crosslinker. As a potential application, fabricated crosslinked polymers were employed as adsorbents to remove toxic mercury ions from water. The reported synthetic strategy demonstrated the efficiency of polysulfide-ene reaction to synthesize sulfur-rich polyamide and polyimide polymers and could broaden the available polymerization reaction tools that employelemental sulfur-derived polysulfide salts in functional polymer synthesis.

Controllable detection threshold achieved through the toehold switch system in a mercury ion whole-cell biosensor

Due to the toxicity of mercury and its harmful effects on human health, it is essential to establish a low-cost, highly sensitive and highly specific monitoring method with a wide detection range, ideally with a simple visual readout. In this study, a whole-cell biosensor with adjustable detection limits was developed for the detection of mercury ions in water samples, allowing controllable threshold detection with an expanded detection range. Gene circuits were constructed by combining the toehold switch system with lactose operon, mercury-ion-specific operon, and inducible red fluorescent protein gene. Using MATLAB for design and selection, a total of eleven dual-input single-output sensing logic circuits were obtained based on the basic logic of gene circuit construction. Then, biosensor DTS-3 was selected based on its fluorescence response at different isopropyl β-D-Thiogalactoside (IPTG) concentrations, exhibiting the controllable detection threshold. At 5-20 μM IPTG, DTS-3 can achieve variable threshold detection in the range of 0.005-0.0075, 0.06-0.08, 1-2, and 4-6 μM mercury ion concentrations, respectively. Specificity experiments demonstrated that DTS-3 exhibits good specificity, not showing fluorescence response changes compared with other metal ions. Furthermore spiked sample experiments demonstrated its good resistance to interference, allowing it to distinguish mercury ion concentrations as low as 7.5 nM by the naked eye and 5 nM using a microplate reader. This study confirms the feasibility and performance of biosensor with controllable detection threshold, providing a new detection method and new ideas for expanding the detection range of biosensors while ensuring rapid and convenient measurements without compromising sensitivity.

Different solvents accompanied by different structures: Catalyst-free one step construction of highly branched polythioureas and its properties

In this study, tris(2-aminoethyl)amine and carbon disulfide were used as raw materials for the construction of highly branched polythioureas. Firstly, a highly branched polythiourea adsorbent was synthesized through a heating condensation reaction using N, N-dimethylformamide (DMF) as solvent without any catalyst. Interestingly, this study also revealed that a highly branched polythiourea resin was successfully synthesized without any catalyst when water was used as the solvent. Through nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), gel chromatography column (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and other means to characterize the comprehensive properties of the polymer. Then, mercury ions were used as the adsorption model. The effects of adsorbent dosing, adsorption time, and different pH on the adsorption of mercury ions (Hg2+) were investigated by intermittent adsorption experiments. The adsorption kinetics, isotherm model, sensitivity test of mercury extraction, single metal ion test, and the adsorption capacity of the adsorbent for nine metal ions were studied. In addition, bond strength tests were utilized to explore the adhesive properties of the prepared aqueous phase highly branched polythioureas. The results show that in the adsorption performance test, when the dosage of highly branched polythiourea adsorbent is 10 mg, the pH is acidic or neutral, and the adsorption time is 60 min, the adsorption efficiency of P-DMF for Hg2+ is as high as 99.99 %. The adsorption follows the Langmuir isotherm model and fits well with the pseudo-second-order kinetic model. In addition, P-DMF has a certain selectivity for Hg2+, and the adsorption efficiency is positively correlated with the mercury ion concentration. When Hg2+ is 100 mg/L, the adsorption efficiency reaches 99.98 %. In the bond strength test, the dry shear strength of the plywood reached 1.6 MPa, and the strength after soaking in hot water and boiling water for 3 h was 1.5 MPa and 1.4 MPa respectively, exceeding the requirements of GB/T9846-2015 for type II plywood (≥0.7 MPa).

Mediating sequential turn-on and turn-off fluorescence signals for discriminative detection of Ag+ and Hg2+ via readily available CdSe quantum dots

Realizing the accurate recognition and quantification of heavy metal ions is pivotal but challenging in the environmental, biological, and physiological science fields. In this work, orange fluorescence emitting quantum dots (OQDs) have been facilely synthesized by one-step method. The participation of silver ion (Ag+) can evoke the unique aggregation-induced emission (AIE) of OQDs, resulting in prominent fluorescence enhancement, which is scarcely reported previously. Moreover, the Ag+-triggered turn-on fluorescence can be continuously shut down by mercury ion (Hg2+). This intriguing sequential fluorescence variation exhibits great sensing potency for discrimination and quantification of Ag+ and Hg2+. Meanwhile, our OQDs also exhibit good selectivity, sensitivity, and rapid response toward Ag+ and Hg2+ detection. Due to their high performance, OQDs have been applied to the determination of Ag+ and Hg2+ levels in daily necessities and water samples with satisfactory results. Moreover, a portable smartphone-assisted sensing platform based on chromatic change has been constructed, facilitating the real-time and naked-eye visualization in the resource-confined scene. We anticipate that the discovery of these OQDs would be advantageous for exploring novel QDs materials for fluorescence detection.

Smartphone-assisted colorimetric sensor based on single-atom Cu–C–N nanozyme for mercury (II) ions detection

Herein, we have developed a novel colorimetric assay for Hg2+ ions assay using single-atom Cu–C–N nanozymes. The nanozymes exhibit exceptional oxidase-like activity, facilitating the oxidation of the colorless substrate, TMB, to its blue oxidized form, ox-TMB. By introducing cysteine, the ox-TMB can be deoxidized back to colorless TMB. The addition of Hg2+ ions, known for their strong affinity towards thiol groups of Cys, resulting in a significant enhancement in TMB oxidation. Therefore, a simple and sensitive colorimetric strategy was established for Hg2+ ions assay in the linearity range of 1 nM–20 μM with LOD was 0.85 nM. The practicability of the detection of Hg2+ ions in water and food samples, which has been verified with satisfactory results. In addition, we have developed a portable sensor platform that integrates nanozyme-based test strips with smartphones, enabling convenient and on-the-go analysis of Hg2+ ions, with LOD of 50 nM.

Metal organic framework-derived CuO/Cu2O polyhedron-CdS quantum dots double Z-scheme heterostructure for cathodic photoelectrochemical detection of Hg2+ in food and environment

This study employed an innovative copper oxide/cuprous oxide (CuO/Cu2O) polyhedron‑cadmium sulphide quantum dots (CdS QDs) double Z-scheme heterostructure as a matrix for the cathodic PEC determination of mercury ions (Hg2+). First, the CuO/Cu2O polyhedral composite was prepared by calcining a copper-based metal organic framework (Cu-MOF). Subsequently, the amino-modified CuO/Cu2O was integrated with mercaptopropionic acid (MPA)-capped CdS QDs to form a CuO/Cu2O polyhedron-CdS QDs double Z-scheme heterostructure, producing a strong cathodic photocurrent. Importantly, this heterostructure exhibited a specifically reduced photocurrent for Hg2+ when using CdS QDs as Hg2+-recognition probe. This was attributed to the extreme destruction of the double Z-scheme heterostructure and the in situ formation of the CuO/Cu2O-CdS/HgS heterostructure. Besides, p-type HgS competed with the matrix for electron acceptors, further decreasing the photocurrent. Consequently, Hg2+ was sensitively assayed, with a low detection limit (0.11 pM). The as-prepared PEC sensor was also used to analyse Hg2+ in food and the environment.

A new Eosin Y-based ‘turn[sbnd]on’ fluorescent sensor for ratiometric sensing of toxic mercury ion (Hg2+) offering unaided eye detection and its antibacterial activity

A unique fluorescent molecule (ND-S) was obtained from Eosin Y in two simple yet high yielding steps (1). ND-S has special metal ion sensing ability, such that it can selectively detect toxic Hg2+ present in very low concentration in aqueous solutions in the presence of other competing metal ions. The host-guest complexation is ratiometric and is associated with significant increase in fluorescence during the process. Isothermal titration calorimetry (ITC) experiments provided thermodynamic parameters related to interaction between ND-S and Hg2+. Using inductively coupled plasma mass spectrometry (ICP-MS), the Hg2+(aq) removal efficiency of ND-S was estimated to be 99.88%. Appreciable limit of detection (LOD = 7.4nM) was observed. Other competing ions did not interfere with the sensing of Hg2+ by ND-S. The effects of external stimuli (temperature and pH) were studied. Besides, the complex (ND-M), formed by 1:1 coordination of ND-S and Hg2+ was found to be effective against the survival of Gram-positive bacteria (S. aureus and B. subtilis) with a high selectivity index. Moreover, bacterial cell death mechanism was studied systematically. Overall, we have shown the transformation of a toxic species (Hg2+), extracted from polluted water by a biocompatible sensor (ND-S), into an effective and potent antibacterial agent (ND-M). Environmental ImplicationMercuric (Hg2+) ions are highly mobile and non-biodegradable water pollutants that biomagnify and adversely affect human health, even in small doses. Herein, a new molecular sensor (ND-S) is synthesized that is capable of sensing and removing Hg2+ ions from water with high selectivity, sensitivity, efficiency, and recyclability. Overall, ND-S is an Eosin Y-based inexpensive sensor that is useful for detection of Hg2+ (a health hazard). The resultant complex (ND-M) possesses superior ability to destroy human pathogens (S. aureus and B. subtilis) that are frequently present in water sources.

Green-AgNPs modified membrane for monitoring mercury ions in cosmetic sample using pre-concentration assisted voltammetry technique

The carcinogenic and teratogenic properties of mercury have driven the necessity for the development of highly sensitive methods capable of detecting even trace amounts of the element. In response to this need, an analysis technique has been established for mercury ions, employing preconcentration methods utilizing filter paper modified by silver nanoparticles (AgNPs) and 3-Amino propyl trimethoxy silane (APTMS). This method allows for the detection of mercury ions through the voltammetry technique, ensuring accurate and reliable results. Upon conducting analyses using this method, it was found that the tested cosmetic samples were free from Hg2+ ions, indicating the absence of mercury contamination in the cosmetics under investigation. The correlation coefficient derived from the graph of the analysis results stands at an impressive value of 0.9976, affirming the strong relationship between the measured concentrations and the actual mercury content. Additionally, the method demonstrates excellent sensitivity, as evidenced by the low limit of detection (LOD) value of 0.0483 mM and the limit of quantification (LOQ) value of 0.1611 mM.

A novel colormetric and light-up fluorescent sensor from flavonol derivative grafted cellulose for rapid and sensitive detection of Hg2+ and its applications in biological and environmental system

Mercury ion (Hg2+) is one of harmful heavy metal ions that can accumulate inside the human organism and cause some health problems. In the article, a highly effective fluorescent probe named EC-T-PCBM was prepared by grafting flavonol derivatives onto ethyl cellulose for the specific recognition of Hg2+. EC-T-PCBM exhibited a remarkable fluorescence light-up response toward Hg2+ with excellent sensitivity. EC-T-PCBM possessed several prominent sensing properties for Hg2+, such as low detection limit (43.9 nM), short response time (5 min), and wide detection pH range (6–9). The response mechanism of EC-T-PCBM to Hg2+ has been verified through 1H NMR titration and DFT computation. Additionally, EC-T-PCBM not only can be used for accurately determining trace amount of Hg2+ in actual environmental water samples, but also can serve as a portable and rapid device by loading it on test strips for sensitive and selective visualization of Hg2+. More importantly, the confocal fluorescence imaging of onion cells suggested the favorable cell membrane permeability of EC-T-PCBM and its prominent ability to continuously monitor the enrichment from Hg2+ within fresh plant tissues.

Morphology-controlled peroxidase-like cuprous oxide-platinum cubes for dual-mode sensing of mercury ions

It is still a challenge to achieve high-precision, rapid, efficient, and accurate detection of toxic mercury ions in complex environmental medium. In this protocol, the controllable and multi-functional Cu2O/Pt cubes were first utilized to construct a colorimetric and photoelectrochemical (PEC) dual-mode sensor for mercury ions. For the colorimetric sensing, compared with Cu2O and Pt particles alone, the Cu2O/Pt cubes creatively prepared by sequential electrodeposition method have simulated peroxidase synergistic catalytic activity against chromophore 3,3′,5,5′-tetramethylbenzidine (TMB) upon exposure to H2O2. Meanwhile, Pt nanoparticles (NPs) can selectively reduce Hg2+ ions, and the resulting Pt-Hg alloys can attenuate the catalytic oxidation. Based on the similar signal suppression strategy, the Cu2O/Pt cubes could also be utilized for PEC sensing of Hg2+ ions since Cu2O is a well-known p-type semiconductor. Based on this unique dual-signal output sensing mechanism, the constructed sensor can be competent for the measurement of Hg2+ in practical settings. This strategy creatively combines the dual functions of Cu2O and Pt to the dual signal expression of sensors. Moreover, the homogeneous distribution of Cu2O/Pt cubes prepared by electrodeposition ensures the stability of dual signal expression, especially for modified electrodes. Additionally, the designed dual-mode sensor has good performance in sensitivity, specificity, simple operation as well as cost-effectiveness and rapid response. In particular, the dual-output sensing strategy enables self-confirmation of detection results, which greatly improves the reliability of the sensor.

Covalent organic polymers based on special dithioureas for efficient removal of Hg2+ from aqueous solutions

The damage caused by mercury ions (Hg2+) to human beings motivates the development of highly efficient technologies for the removal of Hg2+ from water. Here, based on the coordination theory between functional groups and Hg2+, two covalent organic polymers (COPs) materials were successfully prepared by a more environmentally friendly Michael addition elimination reaction, and the thiourea structure, which has a particularly strong affinity for Hg2+, was successfully introduced into the material framework. The introduction of the special dithiourea structure created a rich environment of S and N atoms within the COPs structure, which exhibited high adsorption performance for Hg2+. Adsorption experiments showed that the dithiourea-functionalized COPs exhibited high adsorption capacities for Hg2+, with the maximum adsorption capacities of 840.9 and 880 mg g−1 for the two materials, respectively. The adsorption performance remained relatively good after four adsorption-desorption cycles, and the adsorption selectivity for Hg2+ was intense. Mechanistic studies by X-ray photoelectron spectroscopy and density flooding theory calculations suggest that it is the S atoms within the structure that chelate with the Hg2+ and contribute to the adsorption capacity of the Hg2+. Therefore, this study provides a new strategy for the development of COP adsorbents for efficient removal of Hg2+ in aqueous solutions during remediation activities.

A thiourea dihydropyridine as a highly selective and sensitive “turn-on” fluorescent chemosensor for mercury(II) ion in water and its application for cell imaging

The existence of extremely toxic mercury contaminants in the environment, even at very low concentrations, poses severe human health issues. Mercury exposure may lead to various diseases, such as prenatal brain damage, cognitive severe, motion disorders, and Minamata diseases. Hence, developing an effective and selective method to detect Hg2+ in the environment and biological samples is of great interest. Amongst various Hg2+ detection techniques, fluorescent chemosensors offer more convenient procedures, affordable cost, high selectivity, and the capability to perform cell imaging for Hg2+ detection. Herein, a novel "turn-on" fluorescent chemosensor, Thiourea-DHP derivative (TUD), highly selective to Hg2+, was successfully developed. TUD was synthesized by cyclotrimerization of β-amino acrylate, followed by the thioacylation of the resulting dihydropyridine (DHP) with dimethylamino thiocarbonyl chloride. The Hg2+ detection by TUD displayed an astonishing naked-eye blue fluorescence signal under blacklight, exhibiting an LOD of 69 nM or 14 ppb at pH 7.4 in the HEPES buffer. Hg2+-induced hydrolytic desulfurization of the low fluorescent TUD to produce the strongly fluorescent urea-DHP (UD) is proposed as a mechanism for this fluorescence enhancement. The formation of UD was confirmed by 1H NMR, 13C NMR, and HRMS. This detecting system of TUD provided excellent percentage recovery (>97 %) for the analysis of Hg2+ contaminants in real-environmental water samples. Besides, the TUD probe showed nontoxic properties in living cells towards RAW264.7 murine macrophage cell line even at high concentrations (100 µM). Our proposed TUD probe demonstrated superior sensitivity in pure aqueous media compared to current mercury-desulfurization fluorescent chemosensors. This sensing system proved effective for analysing Hg2+ contaminants in real-environmental water samples. Additionally, the nontoxic TUD probe successfully revealed the remarkable biocompatibility for Hg2+ detection in living cells.

Self-validating photothermal and electrochemical dual-mode sensing based on Hg2+ etching Ti3C2 MXene

Mercury ions can cause serious damage to the ecological environment, and it is necessary to develop reliable and elegant mercury ion sensors. In this protocol, a label-free photothermal/electrochemical dual-mode strategy for Hg2+ is proposed based on delaminated Ti3C2 MXene nanosheets (DL-Ti3C2 MXene). Hg2+ exists in water in the form of HgCl2, Hg(OH)2, and HgClOH, and the electron-rich elements O and Cl can specifically bind to the positively charged DL-Ti3C2 MXene at the edge, and further oxidation-reduction reaction occurs to obtain TiO2/C and Hg2Cl2. In view of the reduction activity and the performance of photothermal conversion of DL-Ti3C2 MXene itself, the electrochemical and photothermal responses decrease with the increase of the logarithm of Hg2+ concentration. The corresponding linear ranges are 50 pmol L−1-500 nmol L−1 and 1 nmol L−1-50 μmol L−1, and their detection limits calculated at 3 S/N are 17.2 pmol L−1 and 0.43 nmol L−1, respectively. DL-Ti3C2 MXene has the characteristics of a wide range of raw materials, low cost, and easy preparation. In addition, the design takes full advantage of the properties of the material itself, avoids the complex assembly and detection process of conventional sensors, and enables high selectivity and sensitivity for mercury detection. In particular, the dual-mode sensing endows self-confirmation of mercury ion detection results, thereby improving the reliability of the sensor.

Fluorescent turn-on detection of inorganic mercury and methylmercury in aqueous solution with PC micelles and live cells using fluorescent chemosensors based on Trp amino acid and cycloalkylamine-7-sulfonyl-2,1,3-benzoxadiazole

Mercury species are well-known to be toxic to humans. Particularly, methylmercury is a highly toxic substance that can readily penetrate lipid membranes, accumulating in human body and causing lethal effects. Thus, the sensitive detection of methylmercury in aquatic environments and live cells is crucial. In this study, we synthesized fluorescent chemosensors (1–5), primarily composed of a tryptophan amino acid (Trp) and cycloalkylamine-7-sulfonyl-2,1,3-benzoxadiazole fluorophores bearing a different size of cyclic amine moiety and developed new sensing systems for Hg2+ and CH3Hg+ by combining the fluorescent chemosensors with lyso-phosphatidylcholine (PC) micelles to resemble cytoplasmic lipid membranes of human cells. Fluorescent chemosensors (1–5) with visible light excitation (>450 nm) exhibited significant enhanced emissions to Hg2+ among various metal ions in purely aqueous solutions. In PC micelles, the chemosensors (1–5) showed significant enhanced green and red emissions (500 ∼ 670 nm) to CH3Hg+ and Hg2+ among various metal ions. Interestingly, the chemosensors have different binding affinities and fluorescent signal changes for CH3Hg+ depending on the size of cyclic amine moiety. Among them, chemosensor 5 with 7-membered cyclic amino group, exhibited the largest fluorescence change for CH3Hg+ and demonstrated the highest binding affinity for CH3Hg+ (Kd = 24.1 μM) and Hg2+ (Kd = 15.8 nM). Chemosensor 5 exhibited a significant enhancement of emission as well as an extremely fast response (<20 sec) for methylmercury in aqueous solution with PC micelles. Thus, we investigated the binding mode of chemosensor 5 with the mercury species in PC micelles using UV/visible absorbance titration, pH titration, and NMR titration experiments. Furthermore, chemosensor 5 was successfully applied to detect sensitively CH3Hg+ and Hg2+ in live cells through increase in both green and red emissions. Fluorescent chemosensors in combination with PC micelles might serve as a promising new fluorescent sensing method for methylmercury and inorganic mercury ions in aqueous solutions and live cells.

Designing and evaluation of thiosemicarbazide-functionalized/ion-imprinted cellulose for selective removal of mercury (II) ion

For aquatic ecosystems, Hg2+ removal from wastewater is crucial. However, getting high-efficiency Hg2+ extraction is still a challenge due to slow rates and poor selectivity. The active thiosemicarbazide (TSC) chelating units were added to the cellulose (CE) in this work using a novel synthetic pathway. The TSC-CE derivative was then used to produce a Hg2+ ion-imprinted sorbent. Initially, the Michael reaction was used to yield cyanoethyl cellulose (CEC). TSC units were combined by a chemical reaction with the added -CN groups. After Hg2+ was attached to TSC-CE, it was cross-linked with glutaraldehyde before being eliminated via elution with HNO3/EDTA. The Hg2+ imprinted sorbent (Hg-TSC-CE) achieved improved adsorption selectivity for Hg2+ and significantly higher adsorption capacity (qm = 353 ± 0.5 mg/g) in comparison to the non-imprinted sorbent. The FTIR and XPS studies both gave strong evidence supporting the kinetic results for the pseudo-second-order model, which said that coordination is the main process of adsorption. The Langmuir model also well explained the isotherms. It showed that Hg2+ mainly adsorption took place in monolayers, with a pHZPC value of about 5.6. Moreover, the Hg2+ adsorption was endothermic, and the optimum pH was observed at 5.

Carbohydrazide-Based schiff bases for selective Hg (II) ion sensing and computational analysis of cholesterol lowering activity

The presence of mercury ion (Hg (II)) in the environment is a serious health concern. Therefore, it is essential to measure and monitor the levels of Hg (II) in the environment to safeguard public health. This study focuses on the synthesis of carbohydrazide-based Schiff bases (4–5) and exhibit a red-shift in absorption upon addition of Hg (II) ion, making them highly selective and sensitive in detecting Hg (II). The confirmation of the synthesized compounds was achieved using (1H and 13C) NMR spectroscopy and mass spectrometry. Additionally, the detection limits towards Hg (II) were determined to be 7.56 × 10-7 M and 1.42 × 10-6 M for compounds 4 and 5, respectively. The 1H NMR spectra provided evidence of interactions between compounds 4–5 and Hg (II) ion. The compounds 4 and 5 were evaluated for Bioactivity, Drug likeness parameters and Prediction of Activity Spectra (PASS) analysis to design a new molecule with a favorable pharmacological profile. Based on the PASS results, molecular docking studies of compounds 4 and 5 were performed with Cholesteryl Ester Transfer Protein (CETP) (PDB ID: 2OBD), revealing inhibitory activity. These findings suggest the potential of these compounds as candidates for antihyperlipidemic or cholesterol-lowering agents.