Selective Ion Detection Research Articles

A colorimetric sensor for the stable and selective detection of mercury ions using PAH-capped silver nanoparticles in an aqueous medium

A colorimetric sensor for the stable and selective detection of mercury ions using PAH-capped silver nanoparticles in an aqueous medium

Two new Cd(II)-based coordination polymers: Dual sensor for sulfamethazine antibiotic and ferric ion

The precise combination of basic functionality and luminescence property can deliver multifunctional coordination polymers (CPs) with multifarious applications such as sensitive and selective detection of antibiotics and metal ions sensing. Herein, two new Cd(II)-based CPs having formula [Cd2(L)(bpy)2(H2O)2·4H2O] (1) and [Cd2(L)(phen)(H2O)] (2) have been synthesized and characterized using mixed ligand strategy by solvothermal reaction of Cd(II) salts using 1,1′-biphenyl-2,3,3′,5′-tetracarboxylic acid (H4L) as the main ligand and 2,2′-bipyridyl (bpy) as co-ligand for CP 1 and 1,10-phenanthroline (phen) as co-ligand for CP 2. The CP 1 possesses (4,4)-connected sql topology, while CP 2 displays 2D bilayer network composed of ring-like Cd2(OCO)6 subunits. The sensing studies indicated that both 1 and 2 can behave as luminescent sensor for sensitive and selective detection of sulfamethazine antibiotic with remarkable quenching and low limit of detection. Additionally, both CPs also displayed selective sensing for Fe3+ ions. The possible alleviation in the luminescence intensities of 1 and 2 in presence of antibiotic have been addressed using theoretical calculations which indicated that charge transfer as well as the weak interaction between antibiotic and CP may be responsible for the decline in the emission intensity.

Development of a novel near-infrared fluorescent probe for selective detection of zinc ions in environmental and food samples

This study presents a novel near-infrared fluorescent probe TZn, which utilizes Dicyanoisophorone as the fluorophore and dipicolylamine (DPA) as the zinc ion recognition group. Selective recognition of zinc ions can be achieved in the near-infrared region（652 nm. And the chelation reaction of the probe TZn is verified through theoretical calculations and HPLC-MS. The probe TZn exhibits a large Stokes shift of 110 nm, a low detection limit (0.31 μM), and high selectivity. The probe TZn can also monitor the zinc ion in living cells and actual food samples.

Smartphone-powered portable chemiresistive sensing system for label free detection of lead ions in water

Lead (Pb) is a toxic heavy metal that can contaminate water sources and cause serious health problems. Detecting Pb in water is essential for protecting public health and the environment. However, the current state of technology heavily depends upon traditional bench-top equipment for detecting toxic heavy metal ions dissolved in water. In this paper we report a portable, label-free chemiresistive sensor for the selective detection of Pb ions dissolved in water. Lithography patterned micro-ineterdigitated electrodes (µIDEs) modified with Graphene oxide (GO) is used as the transducing agent to capture the sensor’s electrical response on a portable readout platform with a smartphone interface. Graphene oxide functionalized with environment friendly oligosaccharide β- Cyclodextrin acts as the sensing material. The sensor’s electrical properties undergo variation in the presence of Pb ions, hence serving as a parameter for successfully detecting the targeted heavy metal ion. The designed sensor is highly selective towards Pb ions, even in the presence of other heavy metal ions, with the lowest detection concentration being 100 pico Molar (pM). The smartphone-powered portable readout circuit, along with the sensor, makes the entire system energy-efficient and cost-effective, providing a quick analysis of the sensor output. Further, an ML algorithm is used to enhance the data analysis and assist the classification based on sensor response.

Surface‐enhanced Raman spectroscopy investigation of PO43− to Ag/Al2O3 nanopatterned substrates binding and its dynamics for sensitive detection of phosphate in water

AbstractWe provide fast and sensitive detection of phosphate dissolved in water using Raman spectroscopy. To this end, phosphate‐scavenging planar core/shell surface‐enhanced Raman spectroscopy (SERS) probes consisting of Al2O3‐capped Ag nanopatterned sapphire substrate were prepared and optimized. Thanks to scavenging, the probes provide enhancement sufficient to readily detect phosphate at levels occurring in water sources. In particular, the SERS probes were successfully tested for selective detection of all phosphate ions and down to 1 M phosphate concentration (30 g/L of phosphorus in the solution). The novelty of our contribution lies in real‐time SERS monitoring of the phosphate Raman markers, which allowed to study the dynamics of phosphate interaction with the nano‐structured surface of the probes. Under natural conditions (neutral to basic environment), the phosphates adsorb on the probes in form of PO in two steps.

A new fluorescent vitamin B6-based probe for selective and sensitive detection Ga3+ ions in the environment and living cells

This paper reports on the synthesis and characterization of a new selective fluorescence probe for gallium ions in water and living cells. Hydrazone of pyridoxal 5′-phosphate and thiophene-3-carbohydrazide was demonstrated to be a “turn-on” fluorescence sensor that can selectively detect Ga3+ with a noticeable appearance of cyan fluorescence in aqueous DMSO. The complex stoichiometry of the probe for Ga3+ was determined through various methods and its structure and electronic spectra were optimized by quantum chemical calculations. The probe showed a low detection limit of 34 nM, and is suitable for river water analysis with high ion recovery and exhibits low toxicity on different cell lines. This study provides valuable insights into the design and optimization of fluorescence probes for selective detection of metal ions.

Integrated Plastic Microfluidic Device for Heavy Metal Ion Detection.

The presence of heavy metal ions in soil, air and water constitutes an important global environmental threat, as these ions accumulate throughout the food chain, contributing to the rise of chronic diseases, including, amongst others, cancer and kidney failure. To date, many efforts have been made for their detection, but there is still a need for the development of sensitive, low-cost, and portable devices able to conduct on-site detection of heavy metal ions. In this work, we combine microfluidic technology and electrochemical sensing in a plastic chip for the selective detection of heavy metal ions utilizing DNAzymes immobilized in between platinum nanoparticles (PtNPs), demonstrating a reliable portable solution for water pollution monitoring. For the realization of the microfluidic-based heavy metal ion detection device, a fast and easy-to-implement fabrication method based on the photolithography of dry photosensitive layers is proposed. As a proof of concept, we demonstrate the detection of Pb2+ ions using the prototype microfluidic device.

Towards sustainable and selective detection of lead Ions: Selaginella bryopteris assisted green synthesis of gold nanoparticles with tunable properties

The detection of highly toxic Pb2+ ions has propelled the exploration of green chemistry as an environmentally benign approach to synthesizing gold nanoparticles (AuNPs) for sensing applications. Herein, a simple green synthesis method is presented without utilizing optimization conditions for stable and well-disperse AuNPs for Pb2+ ions colorimetric sensing. The Selaginella bryopteris plant (SBp) extract as a reducing, capping, stabilizing, and chelating agent was employed in the volume ratio-controlled synthesis of AuNPs. The AuNPs were characterized using UV-Vis, XRD, FTIR, and TEM analysis. The results revealed polycrystalline AuNPs with SPR, particle size, and crystallite size-tunable by SBp extract. The AuNPs bound by Pb2+ ions showed immediate aggregation and excellent selectivity compared to other metal ions (Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Hg2+, Mg2+, Mn2+, Ni2+, Zn2+, and Na+). A linear colorimetric response of AuNPs was observed in the 10–60 µM Pb2+ ions concentration range and the R2 obtained was 0.99654 with LoD of 0.24 µM. The best detection of Pb2+ ions was achieved in a pH range from 3 to 9. The study suggests that the SBp extract-tunable AuNPs synthesis could be used as a sustainable and simple approach for Pb2+ ions detection in the natural environment.

Graphene Oxide-coated interdigitated electrode for selective detection of mercury ions using self-assembled monolayer of mercaptosuccinic acid

Graphene Oxide-coated interdigitated electrode for selective detection of mercury ions using self-assembled monolayer of mercaptosuccinic acid

Polymer-Functionalized Laser-Induced Graphene Electrochemical Sensor for Selective and Sensitive Detection of Fluoride Ions in Real Water Samples

Fluorosis is a worldwide public health problem induced by excess fluoride content in soft and hard tissues in body, necessitating the development of fluoride sensors. This work demonstrated a flexible, cost-effective, quantitative, and selective fluoride (F-) sensor for fluoride ion detection in water samples. The miniaturized sensor was realized on a polyimide sheet by laser ablation, forming a three-electrode system with laser-induced graphene (LIG). The 3-electrode system comprises a working electrode with chemically modified LIG with electropolymerized polymer, LIG coated with Ag/AgCl conductive ink as reference, and a bare LIG as a counter electrode. The surface chemistry and morphology of the sensor were analyzed by physicochemical characterization. The electrocatalytic activity of F <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> ions on the electrode surface was studied using cyclic voltammetry (CV) and chronoamperometry (CA) techniques. The F <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> ions concentration of the proposed sensor was found to be in the linear range from 5 μM to 130 μM. The limit of detection (LoD) and limit of quantification (LoQ) were obtained as 2.218 μM (0.093 ppm), 6.723 μM (0.282 ppm) which are much lesser than the permissible safe limit. The sensitivity was found to be 0.0168 μA/μM∙cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The impact of other parameters, like scan rate, pH influence, interference, and reproducibility, were analyzed and to comprehend the sensor usability in real-time, a lake water sample was also tested and analyzed. The proposed sensor was found to have consistent repeatability and a good recovery rate. Owing to its flexibility, the sensor can further be miniaturized by integrating it into a microfluidic platform.

Chromone-derived chemosensors: an experimental and theoretical study on cyanide detection

ABSTRACT This study introduces chromone-based probes designed for selective cyanide ion detection in acetonitrile. Through various spectroscopic methods, the probes demonstrated a colour change from colourless to yellow, enabling naked-eye detection of cyanide ions. The sensors exhibited high sensitivity (6.2 µM) and selectivity for CN¯ ions over common anions. Computational analyses by FMO, NCI, QTAIM, NBO and EDD analysis confirmed the probes’ suitability for cyanide detection. Overall, the synthesised compounds present a promising solution for practical applications in the field of cyanide ion sensing.

Fabrication of a GUMBOS-based ratiometric organo nanosensor for selective and sensitive detection of perchlorate ions that works in 100% water

This work intends to develop sensitive and easily applicable ionic liquids (ILs)-based fluorimetric sensors for detecting the explosive perchlorate (ClO4-) anions in the presence of other hazards and interferents. We have designed and developed an IL-compromising pyrene butyrate anion-based fluorophoric group of uniform materials based on organic salts (GUMBOS), PBIL, from sodium pyrene butyrate and trihexyltetradecylphosphonium chloride (P66614Cl) by simple ion exchange mechanism. Using reprecipitation methods, pyrene-based water-suspended nano-GUMBOS, nPBIL, has been fabricated and characterized by numerous analytical methods. The fabricated nano-GUMBOS display bright cyan color photoluminescence due to the excimer-like emission confirmed from the color chromaticity diagram. Interestingly, due to the addition of ClO4- ions, there is a blue shift in the UV–visible absorption spectrum of the nPBIL solution with a simultaneous decrease in Mie-scattering. Consequently, there is a continuous decrease in the excimer-like emission of nPBIL with the synchronized increase in monomeric emission. We can conclude from both UV–visible absorption and emission spectra that the ClO4- ion displaces the anionic pyrene butyrate moiety of our nPBIL due to its high polarizability. The limit of detection (LOD) of the as-fabricated sensor is estimated to be 7.17 nM which is very much lower than the US Environmental Protection Agency (USEPA) predicted permeable level of perchlorate in drinking water (15 μgL−1). An efficient test kit has been fabricated and demonstrated for on-site detection of ClO4- ions in remote areas. This ion exchange-mediated substance release from such nano-GUMBOS systems is a distinctive and innovative way to design and develop efficient sensors for precisely detecting and quantifying ClO4- ions.

Highly efficient and selective detection of sulfur ions and picric acid through salamo-Cd(II) coordination polymer chemosensor

A salamo-Cd(II) coordination polymer [Cd(HL)2(4,4ʹ-bipy)]n (CP-Cd(II)) was synthesized by introducing a auxiliary ligand 4,4ʹ-bipy to the host ligand H2L (4-chloro-4ʹ-bromo-6-bromo-6ʹ-tert-butyl-2,2ʹ-[ethylenedioxybis(nitrilomethylidyne)]di-phenol), and used as a fluorescent chemical sensor to detect sulfur ions (S2−) and picric acid (PA). Single crystal X-ray analysis demonstrated that the Cd(II) atom has a slightly distorted hexa-coordinate octahedron configuration and forms an infinite one-dimensional chain structure due to the intervention strategy of the auxiliary ligand. In fluorescence method, the sensor CP-Cd(II) exhibits good selectivity and sensitivity for S2− and PA with fluorescence turn-on and off effects sequentially. Additionally, the quenching efficiency of PA remains unchanged even after the sensor has been used for four cycles. At the same time, the sensor CP-Cd(II) can quickly detect S2− and PA within 10 s, which make them charming, recoverable and reliable luminescent coordination polymer sensor materials for detecting S2− and PA. The sensing mechanisms were attentively explored by mass spectrometry analysis, spectroscopic studies and density functional theory (DFT) calculations. Furthermore, the potential application of the sensor for further detection of S2− ions and PA in environmental systems was studied through actual water sample detection.

Pushing the Limits of Biosensing: Selective Calcium Ion Detection with High Sensitivity via High-k Gate Dielectric Engineered Si Nanowire Random Network Channel Dual-Gate Field-Effect Transistors.

Calcium ions (Ca2+) are abundantly present in the human body; they perform essential roles in various biological functions. In this study, we propose a highly sensitive and selective biosensor platform for Ca2+ detection, which comprises a dual-gate (DG) field-effect transistor (FET) with a high-k engineered gate dielectric, silicon nanowire (SiNW) random network channel, and Ca2+-selective extended gate. The SiNW channel device, which was fabricated via the template transfer method, exhibits superior Ca2+ sensing characteristics compared to conventional film channel devices. An exceptionally high Ca2+ sensitivity of 208.25 mV/dec was achieved through the self-amplification of capacitively coupled DG operation and an enhanced amplification ratio resulting from the high surface-to-volume ratio of the SiNW channel. The SiNW channel device demonstrated stable and reliable sensing characteristics, as evidenced by minimal hysteresis and drift effects, with the hysteresis voltage and drift rate measuring less than 6.53% of the Ca2+ sensitivity. Furthermore, the Ca2+-selective characteristics of the biosensor platform were elucidated through experiments with pH buffer, NaCl, and KCl solutions, wherein the sensitivities of the interfering ions were below 7.82% compared to the Ca2+ sensitivity. The proposed Ca2+-selective biosensor platform exhibits exceptional performance and holds great potential in various biosensing fields.

Aldol-click generated silane: A turn-on fluorescent sensor for Al3+ ion and exploring its anti-Alzheimer activity via molecular docking

Alzheimer's disease (AD) is one of the leading neurodegenerative disorder whose cure is yet to be developed. Elevated levels of Aluminium ion and acetylcholinesterase in brain tissue are main concern for progression of AD. Hence, both detection of Aluminium ion and inhibition of acetylcholinesterase are important research areas that have gained attention. Aldol-generated chalcones and Click-derived triazoles are among the emerging privileged scaffolds for selective and sensitive detection of metal ions and as promising pharmacological drugs. The present work focuses on design and development of ‘chalcogenyl-based triazole coupled organosilane’ that could selectively detect neurotoxic Aluminium ion. The binding strength and ratio between the two was discovered from B–H plot and Job's plot method respectively from fluorescent studies. Further linear calibration curve was utilized to calculate the limit of detection (LOD). The possible binding site of chemosensor for Aluminium ion has been recognized from 1H NMR studies and DFT calculations. Molecular docking, a computational approach was used to scrutinize the synthesized ‘chalcogenyl based triazole coupled organosilane’ as whether it could inhibit the activity of acetylcholinesterase and thus be further examined as potent pharmacological drug in treatment of AD.

Rationally designed novel phenazine based chemosensor with real time Hg2+ sensing application

Phenazine derivatives have been explored in the selective detection of ions due to their binding ability with analytes. In this context, C-6 sulfenylated benzo[a]phenazine-5-ols (3a-d)have been synthesied and explored in sensing application. Initially, the molecules were designed by utilizing benzo[a]phenazin-5-ol as a core structure variably substituted with electronically diverse aryl thiols to investigate the substituent effect on their electrostatic properties. The ground state geometry of all the designed molecules was optimized with DFT using B3LYP/6-311G+(d,p) level of theory. Energy gap between FMOs was observed to be minimum and maximum for electron rich and deficient frameworks, respectively. The LUMO electron density in all the designed molecules except for compound bearing nitro group (3c) lies on the phenazine unit. This exceptional behavior enthusiased us to explore their photophysical properties. The compounds were synthesized and characterized using FT-IR, NMR and mass spectrometric techniques. In an attempt to examine their spectral behavior in different solvents, their absorption and emission spectra were recorded. The compounds exhibited absorptions maxima ranging between 475-514 nm, which shifted to longer wavelength while changing solvent polarity from CHCl3 to DMSO thus depicting positive solvatochromism. Similarly, the emission maxima was observed in a range of 570–685 nm with a maximum stokes shift of 6454 cm−1 for 3c. The compound 3c was further explored in the sensing application using DMSO:Water (60:40, v/v) mixture. A blue shift of 30 nm with nearly 7 fold increase in the emission intensity was observed upon addition of Hg2+ into 3c solution. Moreover, LOD of 21.9 nM and binding stoichiometry of 2:1 as determined by Benesi–Hildebrand and Job's plot establish the robust response of developed probe towards Hg2+ ion. The mechanism of complex formation was predicted by 1H NMR titration and DFT studies. Finally, the developed probe has been successfully utilized for sensing Hg2+ in real water samples.

Gasoline residue-prepared carbon dots embedded metal–organic frameworks for selective and sensitive detection of sulfide ions

Sulfide ions (S2-) are well-known and hazardous pollutants that are commonly found in natural water and wastewater. Their excessive presence can lead to environmental problems and pose a risk to living systems and human health. Therefore, the development of affordable and accurate methods for detecting trace amounts of S2- has become a topic of great interest. This study presents a novel approach to constructing highly fluorescent carbon dots (CDs) using gasoline residue from combustion. The CDs were then embedded into a zeolitic imidazolate framework (ZIF-8) crystal at room temperature, resulting in the creation of a CDs@ZIF-8 nanoprobe for S2- detection. The sensing mechanism was based on the fact that the encapsulation of CDs into ZIF-8 can restrain its fluorescent emission, while fluorescence enhancement could be observed by adding S2- due to the S2- can react with the metal node (Zn2+) of ZIF-8 to release the CDs. The sensing platform achieved a low limit of detection (LOD) of 330 nM and a relative standard deviation (RSD, n = 7) of 0.7% under optimized conditions. The platform was successfully applied to quantify S2- in water and gasoline samples, indicating its potential for practical use. The method proposed in this study is rapid, direct, and sensitive for S2- assay with favorable experimental conditions.

Recyclable Multifunctional Magnetic Fe3O4@SiO2@Au Core/Shell Nanoparticles for SERS Detection of Hg (II)

Mercury ions can be enriched along the food chain and even low concentrations of mercury ions can seriously affect human health and the environment. Therefore, rapid, sensitive, and highly selective detection of mercury ions is of great significance. In this work, we synthesized Fe3O4@SiO2@Au three-layer core/shell nanoparticles, and then modified 4-MPy (4-mercaptopyridine) to form a SERS sensor. Mercury ions in water can be easily captured by 4-MPy which were used as the reporter molecules, and the concentration of mercury ions can be evaluated based on the spectral changes (intensification and reduction of peaks) from 4-MPy. After the mercury ion was combined with the pyridine ring, the peak intensity at 1093 cm−1 increased with the concentration of mercury ion in the range of 10 ppm–1 ppb, while the Raman intensity ratio I (416 cm−1)/I (436 cm−1) decreased with the increase of mercury ion concentration. This magnetically separatable and recyclable SERS sensor demonstrates good stability, accuracy, and anti-interference ability and shows the potential to detect actual samples. Furthermore, we demonstrate that the probe is applicable for Hg2+ imaging in macrophage cells.

Designing of efficient two-armed colorimetric and fluorescent indole appended organosilicon sensors for the detection of Al(III) ions: Implication as paper-based sensor

Metal ions have significant roles in diagnosis, industry, human health, and the environment. To design and develop new lucid molecular receptors for the selective detection of metal ions is important for environmental and medical applications. In the present work, two-armed indole appended Schiff bases conjoined with 1,2,3-Triazole bis-organosilane and bis-organosilatrane skelton sensors for naked eye colorimetric and fluorescent detection sensors for Al(III) are developed. The introduction of Al(III) in sensor 4 and 5 show red shift in UV–visible spectra, changes in fluorescence spectra and immediate color change from colorless to dark yellow. Furthermore, the pH and time response studies were explored for both sensors 4 & 5. The sensors 4 and 5 exhibited significantly low detection limit (LOD) in nano-molar range 1.41 × 10−9 M and 0.17 × 10−9 M respectively from emission titration. The LOD form absorption titration was found to be 0.6 × 10−7 M for sensor 4 and 0.22 × 10−7 M for sensor 5. In addition, the sensing model is developed as paper based sensor for its practical applicability. The theoretical calculations were performed on Gaussian 03 program by relaxing the structures using Density functional theory.

Synthesis of Imino Stabilized Iron Oxide Nanosensor for Selective Detection of Lead Ions

The present work describes the successful preparation of iron oxide nanoparticles (NSB1) stabilized with 4-((2-hydroxybenzylidene)amino)benzoic acid. The characterization has been achieved through ultraviolet visible (UV-Vis), fourier transform infra-red (FTIR) spectroscopy and scanning electron microscopy (SEM) with electron dispersive X-ray elemental analysis (EDX). These magnetic nanoparticles have exhibited significant chemosensing properties in the aqueous media to screen Cr3+, Cd2+, Li+, Co2+, Al3+, Pb2+, Ni2+ and Sr2+ ions. However, lead (Pb2+) ions have shown the highest selectivity as compared to other metal ions without any interference in the competitive ion study. The detection limit of Pb2+ ions was found to be 1.7 µM by this nanosensor. The binding ratio and stoichiometry was found to be 1:1 as measured by Job’s plot. The binding strength was also computed through Benesei-Hildebrand equation.