Detection Of Toxic Metal Ions Research Articles

Aggregation-Induced Emission Phosphorescence Featured Au-Ag Coordination Polymer with a Diphosphine N-Heterocyclic Carbene Ligand for Highly Sensitive Detection of Cr(VI).

Luminescent materials with aggregation-induced emission (AIE) characteristics have been recognized as highly selective and sensitive probes for the detection of toxic metal ions in recent years. In this paper, a Au-Ag cluster-based coordination polymer [Au3Ag3(L)2(CN)6(H2O)2]n [1, L = 1,3-bis((diphenylphosphanyl)methyl)-4,5-dihydro-imidazolylidene] was prepared by in situ generation of the diphosphine N-heterocyclic carbene (PCNHCP)-type ligand L in the presence of the corresponding metal salts. Compound 1 exhibited 530 nm phosphorescence under 380 nm excitation with a QY of 6.30% and a lifetime (τ) of 7.14 μs in the solid state. 1 showed good AIE behavior in the mixture of MeOH/H2O while the best aggregation state (fwater = 90%, QY = 6.79%, τ = 6.70 μs) exhibited selective and sensitive emission quenching toward Cr(VI) ions. Ultralow detection limits of 9.7 ppb (w/w) for Cr2O72- and 17.9 ppb (w/w) for CrO42- were achieved.

Novel controllable (Ba0.8Sr0.2)CO3@Mesoporous silicate core/shell nanocomposite grafted fluorescent probes for colorimetric, sensing, and selective detection of heavy metals

Fluorescent nanosensors are one of the most efficient techniques used for detection of toxic metal ions, based on ligand embedded into mesoporous materials. In this study, four different novel nanosensors NS1, NS2, NS3, and NS4 have been synthesized by incorporating fluorescent probes containing dihydropyridine and dihydropyrimidinone fragments into amino‐functionalized controllable (Ba0.8Sr0.2)CO3@Mesoporous silicate core/shell nanocomposite. The designed nanosensors were characterized by FT‐IR (Fourier‐transform infrared spectroscopy), X‐ray diffraction, transmission electron microscopy (TEM), and nitrogen adsorption–desorption isotherms. Visual naked‐eye observations and emission technique were employed to investigate the recognition and sensing capability of the investigated nanosensors toward various metal ions (Al3+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, and Cu2+). A great quenching in the fluorescence intensity was clearly observed with the majority of studied metal ions for all the nanosensors. The binding constants and limit of detection (LOD) have been calculated. Cu2+ is the strongest binded one with both NS1 and NS2, while Al3+ and Fe3+ are the strongest binded metal ions with NS3 and NS4, respectively. The obtained results confirmed the high ability of the nanosensors to detect heavy metals ions at environmentally relevant concentrations using simple and low‐cost experimental studies with good reversibility and reusability.

A centrifugal microfluidic system for automated detection of multiple heavy metal ions by aptamer-based colorimetric assay

The contamination of aquatic environments with heavy metal ions is characterized by their resistance to natural degradation, leading to their bioaccumulation in plants and animals, consequently posing a significant threat to human health. The detection of toxic metal ions is of great significance in environmental protection and disease prevention. In this work, a rapid and automated method for the simultaneous detection of Pb2+, Hg2+ and As3+ in water was proposed. An aptamer-based colorimetric assay and a centrifugal microfluidic chip to realize the function of sampling, mixing, reaction etc. The microfluidic chip and centrifugal device were properly designed and developed. Besides, the detection parameters were optimized by analyzing the sensitivity and selectivity. Results showed that the detection system was able to realize the automatic detection of the multiple heavy metal ions within 30 min, and the limits of detection for Pb2+, Hg2+ and As3+ were 6.16 ppb, 4.97 ppb and 5.24 ppb. The self-developed system can be utilized as a promising platform for the rapid detection of multiple heavy metal ions in practical applications.

Advances in Portable Heavy Metal Ion Sensors.

Heavy metal ions, one of the major pollutants in the environment, exhibit non-degradable and bio-chain accumulation characteristics, seriously damage the environment, and threaten human health. Traditional heavy metal ion detection methods often require complex and expensive instruments, professional operation, tedious sample preparation, high requirements for laboratory conditions, and operator professionalism, and they cannot be widely used in the field for real-time and rapid detection. Therefore, developing portable, highly sensitive, selective, and economical sensors is necessary for the detection of toxic metal ions in the field. This paper presents portable sensing based on optical and electrochemical methods for the in situ detection of trace heavy metal ions. Progress in research on portable sensor devices based on fluorescence, colorimetric, portable surface Raman enhancement, plasmon resonance, and various electrical parameter analysis principles is highlighted, and the characteristics of the detection limits, linear detection ranges, and stability of the various sensing methods are analyzed. Accordingly, this review provides a reference for the design of portable heavy metal ion sensing.

Aptamer-based colorimetric and lateral flow assay approaches for the detection of toxic metal ions, thallium(i) and lead(ii).

Thallium(i) and lead(ii) ions are heavy metals and extremely toxic. These metals are environmental pollutants, posing a severe risk to the environment and human health. In this study, two approaches were examined using aptamer and nanomaterial-based conjugates for thallium and lead detection. The first approach utilized an in-solution adsorption-desorption approach to develop colorimetric aptasensors for the detection of thallium(i) and lead(ii) using gold or silver nanoparticles. The second approach was the development of lateral flow assays, and their performance was tested with thallium (limit of detection is 7.4 μM) and lead ion (limit of detection is 6.6 nM) spiked into real samples. The approaches assessed are rapid, inexpensive, and time efficient with the potential to become the basis for future biosensor devices.

Development of sulphonated co-polyimide based sensor for metal ions detection in aqueous media

• Sulphonated co-polyimide (OBM-20) was synthesized by thermal imidization. • UV-Vis spectroscopy was carried out to evaluate the sensing behaviour of OBM-20. • Sensor showed appreciable increase in absorption intensity upon interaction with metal ions. • Sensor detected the nM concentration of metal ions under optimized conditions. This study reports a facile approach towards sensing properties of hydrophilic sulphonated co-polyimide (OBM-20) for the detection of metal ions in water through UV-Vis spectroscopy. Anionic sulphonated co-polyimide (OBM-20) was synthesized by a two-step thermal imidization reaction. Hydrophilic anionic sulphonate group possessing strong affinity towards heavy metal ions resulted in improved interaction of OBM-20 with metal ions in aqueous media. OBM-20 showed different absorptions in UV region upon interacting with Ni (II), Co (II), and Cr (III) ions in deionized water at room temperature and neutral pH. Interestingly, OBM-20 demonstrated that it can serve as an optical chemical sensor and metal ion receptor for nanomolar detection of toxic metal ions, particularly Ni (II), Co (II), and Cr (III) existing in aqueous media. Sulphonated co-polyimide resulted in efficient sensing of Ni (II) as compared to slightly larger metals such as Co (II) and Cr (III) in aqueous solution. Ultimately, the assessment of the sensing properties of OBM-20 revealed that it can function as a selective Ni (II) ions sensor.

Cu Nanoparticle-Based Solution and Paper Strips for Colorimetric and Visual Detection of Heavy Metal Ions.

The intrinsic toxicity of heavy metal ions to human health or other species calls for the need to develop an analytical tool for the easy and rapid detection of these ions based on inexpensive and stable nanomaterials. This article describes the potential utility of stable Cu nanoparticles (CuNPs) in the detection of toxic metal ions by solution and paper strip-based methods. For this, first, a dodecyl sulfate ion-stabilized CuNP (DS-CuNP) colloid was synthesized by a chemical reduction method. This was followed by treating the dispersion with heavy metal ions and monitoring the spectral change by spectrophotometric and colorimetric techniques. Among a host of metal ions, Hg2+, Cd2+, and Pb2+ have been found to significantly affect the surface plasmon resonance band of CuNPs by concomitantly altering the color of its solution. Notably, the brownish color of CuNP solution changed readily to milky white in the presence of Hg2+. Furthermore, the fabricated brownish-yellow test paper strips containing DS-CuNPs transformed to a prominent white color in the presence of a few drops of Hg2+ solution. This change in color of the paper strips could be visually detected by the naked eye. The experiments involving the detection of the various ions were carried out by optimizing the experimental conditions qualitatively as well as quantitatively. The limit of detection of the analytes (metal ions) has been found to be 10 μM. Routine analytical techniques like UV–vis spectroscopy, dynamic light scattering, transmission electron microscopy, and Fourier transform infrared spectroscopy formed part of the experiments.

Nanomaterial-based sensors and strategies for heavy metal ion detection

• Focused on the nanomaterial based sensors for heavy metal ions detection. • An overview of the nano-sensors coupled with mass spectrometry, colorimetry, electrochemistry, surface-enhanced Raman scattering and fluorescence. • Summarized the analytical performances, applications and further challenges of the metal-ion sensors. As one of the most serious toxic contaminants, heavy metal ions have severely threatened the living environment and biological system. Accurate and rapid detection of toxic metal ions is indispensable, urging the necessity of fabricating sensors with low cost, easy-to-operate, and high sensitivity. Numerous recent innovations in material science have reenergized this field and led to the emergence of well-defined nano-sensors with diverse structures and functions. Specifically, noble metal nanoparticles, porous nanomaterials, and semiconductors have been applied in sensor construction, coupled with analytical tools such as mass spectrometry, colorimetry, electrochemistry, surface-enhanced Raman scattering, and fluorescence. This review overviews the latest nanomaterials-based heavy metal ions sensors and focuses on their analytical performances, applications, and challenges.

Naked‐eye colorimetric and optical assay of heavy metals based on nano‐architectured prototype of organically functionalized mesoporous titania grafted with 4‐chloro‐2‐(4′‐methyl‐benzothiazol‐2′‐ylazo)‐phenol

Heavy metals are extremely toxic, causing harm to aquatic and human life. Thus, this study focused on developing simple, colorimetric, and low‐cost optical sensors for detection of metal ions with high selectivity and sensitivity. Here, a novel benzothiazole azo‐dye, namely, 4‐chloro‐2‐(4′‐methyl‐benzothiazol‐2′‐ylazo)‐phenol (CMBTAP) was synthesized and characterized by Fourier transform infrared spectroscopy (FT‐IR), 1H‐nuclear magnetic resonance (NMR), 13C‐NMR, and mass spectroscopic techniques. This azo‐dye has been anchored into the amino‐functionalized mesoporous TiO2 which synthesized using pluornic123 and cetyltrimethylammonium bromide as templates to yield CMBTAP‐M‐TiO2 (1) and CMBTAP‐M‐TiO2 (2), respectively. The designed nanosensors were characterized by FT‐IR, transmission electron microscopy, nitrogen adsorption–desorption isotherms, X‐ray diffraction, and thermogravimetric analyses. The colorimetric and optical sensing behavior of CMBTAP and its nanosensor analogs toward different metal ions like Ba2+, Fe3+, Co2+, Ni2+, Cu2+, Cd2+, Hg2+, and Al3+ were explored using naked‐eye observations, steady‐state absorption, and emission techniques. Significant changes in colors, the absorption and emission spectra were observed. The action of these nanosensors is reversible where on adding ethylenediaminetetraacetic acid to the formed complexes, the original absorption and emission spectra of the free sensors are restored, demonstrating that the chelation process is reversible. For CMBTAP and the nanosensors, the binding constants of the complexes formed with the used metal ions, and limit of detection (LOD) were calculated. In comparison with CMBTAP, the results revealed that the nanosensors exhibited a stronger binding affinity, selectivity, sensitivity, and lower LODs for the studied metal ions, implying that the sensing efficiency of CMBTAP is improved after loading onto the nanostructured TiO2. Thus, we have successfully converted the hazardous azo dye into an environmentally safe optical sensor for detection of toxic metal ions in wastewater with high sensitivity.

Fluorescent and Colorimetric Chemosensor for the Detection of Toxic Metal Ions of Mercury and Lead – A Mini Review

Variations in the predictable level of heavy metals ions have an uncompromising influence on living being and their surroundings. Real sample analysis was used to identify the heavy metal ions by using colorimetric and fluorescence techniques. The interaction of metal ions with the receptor has produced observable signals as measured by its photophysical changes. Nitrogen-containing heterocyclic compounds are the greatest weapons for identifying heavy metal ions, owing to their diverse reactivity, readily available substrate, and exquisite photophysical property. The main goal of this mini-review is to examine the current advancements in the structural analysis of nitrogen-containing heterocyclic compound-based fluorescence and colorimetric sensors. The interaction between receptor and metal by electron transfer mechanism and its wide applications have been developed and used for the sensing of heavy metal ions in the past ten years by various research groups about selectivity, sensitivity, reversibility, pH effect, stoichiometric ratio, binding constant, LOD values, and real-time applications.

Simultaneous electrochemical detection of Cd and Pb in aquatic samples via coupled graphene with brominated white polyaniline flakes

Severe toxicity of heavy metal ions and their adverse effects on the ecosystem and health of living species raised a requirement to develop practical detection configurations capable of simultaneous and differentiable detection of toxic metal ions in aquatic samples. In this regard, we have fabricated a high-performance sensor configuration based on the integrated reduced graphene oxide (rGO) flakes with brominated white polyaniline (PANi) flakes toward the prompt and accurate detection of Pb (II) and Cd (II) in biological and non-biological specimens. The as-developed configuration simultaneously identified both Pb (II) and Cd (II) through a differentiable manner with a limit of detection (LOD)/quantification limit (QL) of 7.3 nM/85 nM and 6.5 nM/92 nM, respectively. The sensor also showed superior sensitivity of about 4547.77 and 3914.01 µA.µM−1.cm−2 toward Pb (II) and Cd (II), respectively, along with a favorable recovery rate in actual human blood plasma and wastewater samples. The as-developed complex proved to be an ideal platform for simultaneous detection/recovery of heavy metal ions in various aquatic samples.

Identification of heavy metal ions from aqueous environment through gold, Silver and Copper Nanoparticles: An excellent colorimetric approach

Heavy metal pollution has become a severe threat to human health and the environment for many years. Their extensive release can severely damage the environment and promote the generation of many harmful diseases of public health concerns. These toxic heavy metals can cause many health problems such as brain damage, kidney failure, immune system disorder, muscle weakness, paralysis of the limbs, cardio complaint, nervous system. For many years, researchers focus on developing specific reliable analytical methods for the determination of heavy metal ions and preventing their acute toxicity to a significant extent. The modern researchers intended to utilize efficient and discerning materials, e.g. nanomaterials, especially the metal nanoparticles to detect heavy metal ions from different real sources rapidly. The metal nanoparticles have been broadly utilized as a sensing material for the colorimetric detection of toxic metal ions. The metal nanoparticles such as Gold (Au), Silver (Ag), and Copper (Cu) exhibited localized plasmon surface resonance (LPSR) properties which adds an outstanding contribution to the colorimetric sensing field. Though, the stability of metal nanoparticles was major issue to be exploited colorimetric sensing of heavy emtal ions, but from last decade different capping and stabilizing agents such as amino acids, vitmains, acids and ploymers were used to functionalize the metal surface of metal nanoparticles. These capping agents prevent the agglomeration of nanoparticles and make them more active for prolong period of time. This review covers a comprehensive work carried out for colorimetric detection of heavy metals based on metal nanoparticles from the year 2014 to onwards.

Recent progress on graphene quantum dots-based fluorescence sensors for food safety and quality assessment applications.

The versatile photophysicalproperties, high surface-to-volume ratio, superior photostability, higher biocompatibility, and availability of active sites make graphene quantum dots (GQDs) an ideal candidate for applications in sensing, bioimaging, photocatalysis, energy storage, and flexible electronics. GQDs-based sensors involve luminescence sensors, electrochemical sensors, optical biosensors, electrochemical biosensors, and photoelectrochemical biosensors. Although plenty of sensing strategies have been developed using GQDs for biosensing and environmental applications, the use of GQDs-based fluorescence techniques remains unexplored or underutilized in the field of food science and technology. To the best of our knowledge, comprehensive review of the GQDs-based fluorescence sensing applications concerning food quality analysis has not yet been done. This review article focuses on the recent progress on the synthesis strategies, electronic properties, and fluorescence mechanisms of GQDs. The various GQDs-based fluorescence detection strategies involving Förster resonance energy transfer- or inner filter effect-driven fluorescence turn-on and turn-off response mechanisms toward trace-level detection of toxic metal ions, toxic adulterants, and banned chemical substances in foodstuffs are summarized. The challenges associated with the pretreatment steps of complex food matrices and prospects and challenges associated with the GQDs-based fluorescent probes are discussed. This review could serve as a precedent for further advancement in interdisciplinary research involving the development of versatile GQDs-based fluorescent probes toward food science and technology applications.

A responsive pure DNA hydrogel for label-free detection of lead ion

It is of great significance to develop facile and economical strategies for on-site detection and treatment of toxic metal ions. Stimulus-responsive DNA hydrogel materials have been increasingly used for convenient detection of metal ions due to their advantages such as simplicity, portability, and ease of storage. However, these methods still require encapsulation of signal tags by labeling or embedding. In this paper, a one-step preparation of Pb2+-responsive pure DNA hydrogel material was designed to realize a new label-free strategy for Pb2+ biosensing. The Pb2+-dependent DNAzyme strand and substrate strand were introduced to fabricate the DNA hydrogel. The presence of Pb2+ in the sample activates the enzyme strand in the hydrogel skeleton and triggers the cleavage of the substrate, thereby destroy the hydrogel structure. DNA fragments released by the collapsed hydrogel were readily measured as signal output for quantifying Pb2+ concentrations with a minimum detection limit of 7.7 nM. We successfully eliminated the need for embedding or labeling of signal molecules by using the DNA molecules that construct hydrogels as the signal output. And the newly developed method for label-free detection of Pb2+ based on pure DNA hydrogel is simple, easy readout, and cost-effective. By adjusting the DNAzyme and substrate sequences, label-free analysis of other metal ions can also be achieved. We expect that our strategy can be applied to the field detection of toxic metal ions.

Recent advances in transition metal carbides and nitrides (MXenes): Characteristics, environmental remediation and challenges

• Recent advances in Mxenes for environmental application are systematically reviewed. • Strategies for ameliorating the environmental performance are thoroughly discussed. • A targeted discussion corresponding to the properties-performance relationship is outlined. • The current challenges and perspectives in this research area are provided. MXenes, as newly emerging two-dimensional (2D) transition metal carbides and nitrides, have become promising candidates for environmental remediation and detection due to their hydrophilicity, metallic conductivity, versatile surface chemistry and 2D layered atomic structure. Nevertheless, little attention has been paid to the relationship between the properties of MXenes and their environmental performances. Herein, based on the recent experimental and theoretical research, a systematic review about the environmental applications of MXenes and MXenes-based materials including the removal and detection of toxic metal ions and organic contaminants, capture and mitigation of gas, hydrogen production, membrane- based separation, and disinfection has been done. Various design strategies of MXenes on ameliorating application performance are mentioned, and their suitability in multifarious environmental applications is thoroughly discussed. Based on the specific requirements of the final environmental applications, a targeted description between their properties and their abilities for environmental application is provided. Finally, current challenges and perspectives in this field are proposed from our personal insights. Particular emphasis in this review is directed toward the importance of understanding ultimate the aim and the required attributes to develop the proper materials for specific applications, and facilitates the further evolution of MXenes in environmental applications.

Structure analysis and evaluation of two probes for the colorimetric detection of Hg2+ and turn-on fluorescence-based detection of Cd2+ ions in an aqueous solution

Synthetic molecular probes with fluorescent and colorimetric signals are valuable tools for the detection of toxic metal ions. Therefore, two synthetic molecular probes based on quinoline moiety were prepared by substituting it with a sulfonate group and piperidine or morpholine moieties. Quinoline integrated probes were characterized via 1H, 13C-NMR, and single-crystal X-ray crystallography techniques. The structures were further investigated using the crystal explorer program. The intermolecular interactions were quantitatively explored using Hirshfeld surface analysis and 2-D fingerprint plots. The strength of intermolecular interactions was further investigated using the TONTO program at the B3LYP/6-31(d,p) level of theory. The integrated receptors were capable of selectively detecting Hg2+ and Cd2+ ions in aqueous media using UV-Visible and fluorescence spectroscopy, respectively. The structural design of the probe was such that it could selectively signal the presence of the metal ions. The receptors produced enhanced fluorescence intensity in the presence of Cd2+ ions, while no fluorescence emission was observed for Hg2+ ions. The computational study based on M062X/6-31+G(d)-LANL2TZ was used to further investigate the structure of the molecular probe and their complexes.

A dual responsive probe based on bromo substituted salicylhydrazone moiety for the colorimetric detection of Cd2+ ions and fluorometric detection of F‒ ions: Applications in live cell imaging

A dual responsive probe based on bromo substituted salicylhydrazone moiety for the colorimetric detection of Cd2+ ions and fluorometric detection of F‒ ions: Applications in live cell imaging

Nanomaterial-Integrated Cellulose Platforms for Optical Sensing of Trace Metals and Anionic Species in the Environment.

The development of disposable sensors that can be easily adapted to every analytical problem is currently a hot topic that is revolutionizing many areas of science and technology. The need for decentralized analytical measurements at real time is increasing for solving problems in areas such as environment pollution, medical diagnostic, food quality assurance, etc., requiring fast action. Despite some current limitations of these devices, such as insufficient detection capability at (ultra)trace level and risk of interferent effects due to matrix, they allow low-cost analysis, portability, low sample consumption, and fast response. In the last years, development of paper-based analytical devices has undergone a dramatic increase for on-site detection of toxic metal ions and other pollutants. Along with the great availability of cellulose substrates, the immobilization of receptors providing enhanced recognition ability, such as a variety of nanomaterials, has driven the design of novel sensing approaches. This review is aimed at describing and discussing the different possibilities arisen with the use of different nanoreceptors (e.g., plasmonic nanoparticles, quantum dots, carbon-based fluorescent nanoparticles, etc.) immobilized onto cellulose-based substrates for trace element detection, their advantages and shortcomings.

Recent advances in carbon based nanomaterials as electrochemical sensor for toxic metal ions in environmental applications

Toxic metal ions are environmental pollutants that are non-biodegradable and hazardous for which World Health Organization has set a maximum permissible limit for safe drinking water. Various spectroscopic techniques are already in practice to monitor these toxic metals but electrochemical sensors have caught our attention because of their portability, low-cost and fast response. The sensitivity of these electrochemical sensors can be further improved by modifying with carbon based nanomaterials (CBNMs) because of their high conductivity, surface area and broad working potential. The review provides recent advances in the use of electrochemical sensors fabricated with CBNMs for detection of toxic metal ions.

Graphitic carbon nitride embedded-Ag nanoparticle decorated-ZnWO4 nanocomposite-based photoluminescence sensing of Hg2+

Ag loaded metal tungstate-organic framework-based nanocomposite (g-C3N4/Ag/ZnWO4), which generates greater number of oxygen defects plays crucial role in the selective detection of toxic metal ions in solution.