Selective Ion Detection Research Articles

Demonstration of Selective Single-Barium Ion Detection with Dry Diazacrown Ether Naphthalimide Turn-on Chemosensors.

Single-molecule fluorescence imaging (SMFI) of gas-phase ions has been proposed for "barium tagging," a burgeoning area of research in particle physics to detect individual barium daughter ions. This has potential to significantly enhance the sensitivity of searches for neutrinoless double-beta decay (0νββ) that is obscured by background radiation events. The chemistry required to make such sensitive detection of Ba2+ by SMFI in dry Xe gas at solid interfaces has implications for solid-phase detection methods but has not been demonstrated. Here, we synthesized simple, robust, and effective Ba2+-selective chemosensors capable of function within ultrapure high-pressure 136Xe gas. Turn-on fluorescent naphthalimide-(di)azacrown ether chemosensors were Ba2+-selective and achieved SMFI in a polyacrylamide matrix. Fluorescence and NMR experiments supported a photoinduced electron transfer mechanism for turn-on sensing. Ba2+ selectivity was achieved with computational calculations correctly predicting the fluorescence responses of sensors to barium, mercury, and potassium ions. With these molecules, dry-phase single-Ba2+ ion imaging with turn-on fluorescence was realized using an oil-free microscopy technique for the first time-a significant advance toward single-Ba2+ ion detection within large volumes of 136Xe, plausibly enabling a background-independent technique to search for the hypothetical process of 0νββ.

Highly selective and rapid detection of silver ions by using a "turn on" non-fluorescent cysteine stabilized gold nanocluster probe.

Cysteine is widely used as a stabilizer for the preparation of fluorescent gold nanoclusters (Au NCs) with different fluorescence properties. Herein, by using cysteine as a stabilizer and controlling the synthesis conditions, a new non-fluorescent cysteine stabilized gold nanocluster (Cys-Au NCs) probe was prepared and a new strategy for "turning on" the fluorescence of the Cys-Au NCs was studied for rapid and selective detection of silver ions. In this strategy, the addition of silver ions to non-fluorescent Cys-Au NCs solution could quickly induce a visible fluorescence "turn on" phenomenon in 30 s. Further studies indicated that this fluorescence "turn on" phenomenon is specific for silver ions and the "turn on" fluorescence intensity has a linear relationship with the amount of silver ions in the range from 3.0 to 30.0 μM. Therefore, the non-fluorescent Cys-Au NCs were applied to the detection of silver ions in environmental water samples and a limit of detection (LOD) of 0.26 μM was obtained. This research sheds light on new applications of Au NCs and proposes a simple, rapid, sensitive, and visual method for the detection of metal ions.

Dual-emission ratio fluorescence for selective and sensitive detection of ferric ions and ascorbic acid based on one-pot synthesis of glutathione protected gold nanoclusters.

A fluorometric method was proposed for the determination of Fe3+ and ascorbic acid (AA) based on blue and red dual fluorescence emissions of glutathione (GSH) stabilized-gold nanoclusters (AuNCs). AuNCs were synthesized from GSH and tetrachloroauric acid. The fluorescence peaks of AuNCs were at 425 nm and 585 nm, respectively. In the presence of Fe3+, the fluorescence peak at 425 nm can be enhanced and that at 585 nm can be quenched. There is a good linear relationship between the fluorescence intensity ratio for the 425 and 585 nm peaks (F425/F585) and the concentration of Fe3+ in the range of 0.75–125 μM. However, when AA was added to the AuNCs–Fe3+ system, the value of F425/F585 decreased consistently with the concentration of AA in the range of 0.25–35 μM. The limit of detection for Fe3+ and AA was 227 and 75.8 nM, respectively. The interaction between AuNCs and Fe3+ can induce the ligand–metal charge transfer (LMCT) effect leading to the fluorescence increment at 425 nm, while AA can reduce Fe3+ to Fe2+. The production of Fe2+ can not enhance or quench the fluorescence of AuNCs. By comparison with previous literature, the AuNCs prepared here show two fluorescence peaks without additional fluorescence labels. Furthermore, the method was successfully applied in the determination of Fe3+ and AA in some real samples, such as water, human serum and tablets.

A red luminescent Eu3+ doped conjugated microporous polymer for highly sensitive and selective detection of aluminum ions

A Eu3+ doped-CMP composite can be used as a chemosensor for highly sensitive and selective detection of Al3+.

Highly selective and sensitive detection of arsenite ions(III) using a novel tetraphenylimidazole-based probe.

More than 200 million people in the world are exposed to areas where the arsenic concentration exceeds the limit allowed for living species, which urges researchers to develop low-cost methods for the selective and fast detection of arsenic ions in environmental samples. Herein, we report a novel tetraphenylimidazole-based probe (TBAB) functionalized with a Schiff base for sensing and detecting arsenic ions in aqueous media. Upon the addition of arsenic ions, an obvious fluorescence change from faint yellow to green was observed visible to the naked eye. The probe can detect arsenic selectively in the presence of interfering substances, with a lower detection limit than 0.7 ppb, a value which is far lower than the limit set by the WHO. A detailed mechanism revealed that the chelation of TBAB with arsenic activated the AIE characteristic, leading to the enhanced fluorescence, which was verified by Job's plot experiment and HRMS. Its practicality was further validated by the analysis of real water samples, demonstrating its potential application for on-site detection and biological application.

Fluorescent N-functionalized carbon nanodots from carboxymethylcellulose for sensing of high-valence metal ions and cell imaging.

A convenient and sensitive reversible-fluorescence sensing platform for accurate monitoring of high-valence metal ions is still very challenging. As a green kind of fluorescent carbon nanomaterials, carbon dots (CDs) have captured considerable attention because of the stable fluorescence property and low cost. Herein, we fabricated a type of nitrogen-functionalized carbon dots (N-CDs) from CMC as a fluorescent reversible sensing platform for detecting various high-valence metal ions. N-CDs with a mean size of 2.3 nm were obtained and possessed 22.9% quantum yields (QY). A label-free fluorescent probe for detection of high-valence metal ions (Fe3+, Cr6+, Mn7+) was established via the fluorescence quenching response. Among them, the detection limit (LOD) toward Fe3+ ions reached 0.8 µM. We have explored the quenching mechanism of N-CDs to explain the valence state-related electron-transfer fluorescence quenching between high-valence metal ions and N-CDs. Moreover, the valence state-related fluorescence quenching phenomenon of N-CDs in aqueous solution could be effectively recovered by introducing a reducing agent (Ti3+). This “turn off-on” fluorescence recovery system of N-CDs could be applied in different applications covering the selective detection of environmental high-valence metal ions and cellular imaging.

Selective detection of mercury ions based on tin oxide quantum dots: performance and fluorescence enhancement model

The synthesized SnO2 QDs show excellent selective sensing performances in the detection of Hg2+ ions. An adsorption model is established for the mathematical description of fluorescence response of the SnO2 QDs sensor.

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.

Multi-resonance organoboron-based fluorescent probe for ultra-sensitive, selective and reversible detection of fluoride ions

This multiple resonance organoboron-based fluoride ion sensor exhibited a record low detection limit together with good selectivity and reversibility.

Controllable polymeric pseudo-crown ether fluorescent sensors: responsiveness and selective detection of metal ions

A series of responsive polymeric fluorescent sensors were fabricated by post-grafting pyrene and poly(ethylene glycol) onto the backbone of a pseudo-crown ether containing cyclopolymers, and showed good selective recognition toward metal ions.

Urea-doped carbon dots as fluorescent switches for the selective detection of iodide ions and their mechanistic study.

A facile and green strategy for the fabrication of fluorescent urea-doped carbon dots (N-CDs) has been explored. Significantly, the fluorescent N-CDs could recognize iodide ions (I−) with high selectivity, and their photoluminescence could be efficiently quenched by the addition of I−. The sensitivity analysis for I− indicated a linear relationship in the range from 12.5 to 587 μM with the detection limit as low as 0.47 μM. Furthermore, the I− induced fluorescence (FL) quenching mechanism was investigated employing a combination of techniques, including UV-vis/fluorescence spectroscopy, Density Functional Theory (DFT) calculation, TEM and time-resolved fluorescence decay measurements. The DFT calculation results demonstrated that the amino- and amide groups of N-CDs play a significant role in iodide recognition through the formation of multiple N–H⋯I−, C–H⋯I− and C( Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O)N–H⋯I− interactions with I−. The TEM experiment confirmed the aggregation process when I− was added to the N-CDs solution. Moreover, the radiative decay rate of N-CDs, which was first measured and reported the kinetic behaviors of the FL-quenching process, decreased from 3.30 × 107 s−1 to 1.95 × 107 s−1 after the coordination with I− ions. The reduced lifetime demonstrated that the excited energy dissipation led to a dynamic quenching process. Therefore, such carbon materials can function as effective fluorescent switches for the selective detection of I− ions.

In vitro selection and application of lanthanide-dependent DNAzymes.

Highly sensitive and selective detection of lanthanide ions is a major analytical challenge. In recent years, the use of DNA for this purpose has been pursued. For such highly charged cations, it is difficult to select their aptamers due to strong nonspecific binding. On the other hand, the use of catalytic DNA or DNAzymes has an advantage to overcome this problem, especially DNAzymes with RNA-cleaving activity. In this chapter, a few such DNAzymes are introduced and methods for in vitro selection of lanthanide-dependent RNA-cleaving DNAzymes are described in detail, including the selection protocols, the DNA sequences used, the characterization of selected DNAzymes and their conversion into biosensors. All of the experiments use only fluorophore-labeled DNA, and radioisotope labeling is completely avoided. The resulting DNAzymes can distinguish lanthanides from non-lanthanide metals, tell the difference between light and heavy lanthanides, and can be used together to discriminate individual lanthanides.

Iron and nitrogen-co-doped carbon quantum dots for the sensitive and selective detection of hematin and ferric ions and cell imaging.

Iron, nitrogen-co-doped carbon quantum dots (Fe,N-CDs) were prepared via a simple one-step hydrothermal method. The quantum yield of fluorescence reached about 27.6% and the blue-emissive Fe,N-CDs had a mean size of 3.76 nm. The as-prepared carbon quantum dots showed good solubility, a high quantum yield, good biocompatibility, low cytotoxicity, and high photostability. Interestingly, the as-prepared Fe,N-CDs exhibited good selectivity and sensitivity toward both hematin and ferric ions, and the limit of detection for hematin and ferric ions was calculated to be about 0.024 μM and 0.64 μM, respectively. At the same time, Fe,N-CDs were used for imaging HeLa cells and showed that most Fe,N-CDs were detained in the lysosome. Thus, this fluorescent probe has potential application in the quantitative detection of hematin or Fe3+ in a complex environment and for determining Fe3+ at the cellular level.

Highly sensitive and selective colorimetric detection of dual metal ions (Hg2+ and Sn2+) in water: an eco-friendly approach.

Application of an alliin-based precursor for the synthesis of silver nanoparticles (Ag NPs) which is an emerging, reliable and rapid sensor of heavy metal ion contaminants in water is reported here. The Ag NPs were characterized by using UV-visible spectroscopy, X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy analysis techniques. The Ag NPs simultaneously and selectively detect Hg2+ and Sn2+ ions from aqueous solution. The sensitivity and selectivity of the prepared Ag NPs towards other representative transition-metal ions, alkali metal ions and alkaline earth metal ions were also studied. For more precise evidence, a density functional theory study was carried out to understand the possible mechanism and interaction in the detection of Hg2+ and Sn2+ by Ag NPs. The limits of detection for Hg2+ and Sn2+ ions were found as 15.7 nM and 11.25 nM, respectively. This assay indicates the possible use of garlic extract-synthesized Ag NPs for sensing Hg2+ and Sn2+ in aqueous solution very significantly. So, the simple, green, eco-friendly and easy method to detect the dual metal ions may further lead to a potential sensor of heavy metal ion contaminants in water of industrial importance.

Polymer surface ligand and silica coating induced highly stable perovskite nanocrystals with enhanced aqueous fluorescence for efficient Hg2+ and glutathione detection.

The poor stability and aqueous-quenching of fluorescence of perovskite nanocrystals (NCs) hinder their application in bio-detection and bio-imaging. Herein, through the synergistic effects of polymer surface ligand and silica encapsulation, highly stable and enhanced aqueous fluorescent CsPbBr3-mPEG@SiO2 NCs were synthesized and used as a novel "on-off-on" fluorescent probe for highly sensitive and selective detection of mercury ions (Hg2+) and glutathione (GSH) in aqueous solutions. The effects of the methoxypolyethylene glycol amine (mPEG-NH2) ligand and silica encapsulation on the stability and aqueous fluorescence of the CsPbBr3 NCs were studied. It indicated that the aqueous fluorescence of perovskite NCs was increased by 2.59 times. The water stability was also greatly improved, with the NCs maintaining 73% of their original fluorescence after storage for 30 days in water. X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR) analyses further demonstrated that the NCs were successfully passivated by mPEG-NH2 and silica. The fluorescence of the CsPbBr3-mPEG@SiO2 nanocrystals was effectively quenched by Hg2+ which is attributed to the electron transfer process between NCs and Hg2+. Then, through the interaction between Hg2+ and GSH, the restoration of fluorescence for CsPbBr3-mPEG@SiO2 was realized. The "on-off-on" fluorescent probe can be used for the detection of Hg2+ and GSH with a low detection limit of 0.08 nM and 0.19 μM, respectively. It also shows a fast response time and high accuracy for practical sample detection. The simple and sensitive fluorescent probe of CsPbBr3-mPEG@SiO2 shows great potential in environmental and biological sensing.

N,S-doped carbon quantum dots as a fluorescent probe for palladium(II) ions via Förster resonance energy transfer

The wide use of palladium in chemical industry may lead to the serious environmental issue. In this work, we reported a green light emitted nitrogen-sulfur-doped carbon quantum dots (N,S-GCDs) as a fluorescent probe for the selective and sensitive detection of palladium ions (Pd2+) in photoluminescence quenching via Förster resonance energy transfer (FRET). Under optimal conditions, the as-prepared N,S-GCDs exhibited a good linear relationship between fluorescence response and Pd2+ concentration ranging from 0 to 150 µM with a detection limit of 0.12 µM. Furthermore, the N,S-GCDs probe has also been used to detect Pd2+ in real water samples.

The Application of Perovskite Quantum Dots in Photodetectors

Perovskite quantum dots (PQDs) can adsorb visible light and give out fluorescence or excited electron to the surroundings. Therefore, some kinds of PQDs can be used for light detection. Due to the appropriate band gap, cesium bromide and iodide-based perovskite PQDs (i.e. CsPbX3) are especially suitable for visible light detection. Some other kinds of PQDs with different photoluminescence spectrum can be used to detect ultra-violet light or infrared light. In this paper, PQD-based photodetectors are divided into three categories: photoresistors, photodiodes and field effect transistors. Herein, the device structures, characteristics and mechanism of these three types of PQD-based photodetectors are briefly reviewed. Other applications of PQDs are also briefly introduced, including selective ion detection and organic molecular detection associated with molecular imprinted polymers.

Synthesis of dual-emissive ratiometric probe of BSA-Au NCs and BSA-Cu NCs and their sensitive and selective detection of copper and mercury ions

Herein, we synthesized bovine serum albumin-functionalized gold nanoclusters (BSA-Au NCs) and BSA-Cu nanoclusters (Cu NCs) by a facile and environmentally-friendly method, and simply mixed them to develop a ratiometric fluorescent sensor for mercury (Hg2+) and copper (Cu2+) ions detection, respectively. The as-prepared BSA-Au NCs were known to emit pink color fluorescence (peaking at 616 nm) and BSA-Cu NCs were blue-emitting (peaking at 398 nm) upon the exposure of ultraviolet light (365 nm). Among them, BSA-Au NCS was used as the response signal and BSA-Cu NCs was the reference signal. Interestingly, when the easily prepared ratiometric probe were employed to detect 15 kinds of common metal ions, only Hg2+ and Cu2+ ions could significantly quench the pink fluorescence of BSA-Au NCs. We found that the fluorescence intensity ratio (I616 /I398) of the nanohybrid system was efficiently reduced by the addition of Hg2+ and Cu2+ ions compared to a series of metal ions. The response of the nanohybrid probe to Cu2+ showed an excellence linear relationships in the concentration range of 0.1∼1 μM and 1∼5 μM respectively, and its detection limit was 23.4 nM. Moreover, the fluorescence quenching caused by Hg2+ ions exhibited excellent and wide linear relationships from 0.06 to 1 μM and 1–4 μM respectively, with detection limits as low as 19.4 nM. With the increase of Cu2+/Hg2+ concentration, this nanohybrid probe also showed obvious fluorescence color changes that could be directly observed by the naked eye.

New Schiff Base as Selective and Sensitive Detection of Copper Ions in Aqueous Solvent

AbstractDetection of metals in aqueous solution is advantageous in the field of food, nutrition and drug chemistry. Hence, a new sensor was designed for the selective and sensitive detection of Cu2+ ions in the aqueous media. Herein, Schiff base L=(E)‐N′‐((1H‐indol‐2‐yl)methylene)isonicotinohydrazide acts as a sensor which consist of isaniazid and indole moiety connected with azomethine linkage. Single crystal X ray analysis along with other spectroscopic methods was used to confirm the structure of the synthesized ligand. Theoretical calculations were performed which gave satisfactory correlation with experimental results. A naked eye color change from colorless to yellow was observed upon addition of Cu(II) ions in synthesized Schiff base sensor. UV‐Visible absorption spectroscopy was used for the further sensing experiments and a red shift of 63 nm was observed only in the case of Copper ions in a pH range of 6–8, this confirms the selective nature of Schiff base sensor towards the Cu2+ ions. Negligible interference of other metal ions in the sensing of copper ions was confirmed by interference study.Calculated limit of detection for copper detection in aqueous media was 0.05 μM. To check the practical applications of the studied Schiff base as a chemosensor, test strips test was also performed.

High performance chemical sensor with field-effect transistors array for selective detection of multiple ions

Monitoring of phosphate, nitrate, and potassium ions in nutrient solution or water, which play critical roles in all living organisms, is important in regulating and/or supplying right amount of such essential nutrients for plant growth in a smart farm. Herein, we report a novel approach for simultaneous, selective detection of multi-ions with ZnO nanorods field-effect transistors (FETs) array sensor. The fabricated sensor platform provided fast responses to wide linear ranges of PO4−3, NO3−, and K+ ions with high sensitivity and selectivity and low detection limits. More importantly, the chemical sensor platform is successfully used for detection of multiple ions in a real nutrient solution, showing an excellent agreement of 98–100% and remarkable stability and reproducibility of sensing performance, indicating a great potential to become a useful tool not only for hydroponic cultivation in a smart farm but also for a water maintaining system.