Applications In Ion Detection Research Articles

Tellurenated Compounds: Synthesis and Application in Ion Detection and as a Catalyst

AbstractTellurium is now recognized as a ‘technology-critical element’ that is quickly being used in innovative applications. The chemistry of organotellurium ligands has improved rapidly during the last three decades. Because of their enhanced accessibility and the possibility that they would display significantly different properties than their sulfur counterparts, these ligands of heavier chalcogens have sparked considerable attention. The next sections will go through the various tellurium ligands and associated transition-metal complexes. Organochalcogen ligands are exceedingly flexible ligands that may react with nearly any transition metal to form a wide range of compounds, including multidentate ligands.Tellurides of various metals have lately been investigated for potential use in storage devices, solar cells, piezoelectric, medical applications, electronics, photothermal treatment, nanoplatelets, nanocrystals, catalysis, and other fields. Researchers are interested in metal chalcogenide heterostructures because of their improved charge transport and synergistic optoelectronic and catalytic properties. A sensor for various metals based on Te electrodes and a donor ligand are used to generate electrical signals and identify different metals. Due to the scarcity of tellurium, metal telluride nanocrystal heterostructures have received less attention than metal sulfide and metal selenide nanocrystal heterostructures.1 Introduction2 Tellurenated Compounds of Zwitterionic Nature3 Synthesis of Tellurenated Ligands and Complexes4 Catalytic Application and and Suzuki–Miyara Coupling5 Tellurenated Sensors for Metal-Ion Sensing5.1 Tellurium-Ion Detectors5.2 Drawbacks/Catalyst Poisoning5.3 Disadvantages5.4 Advantages and Future Prospects6 Conclusions

Elucidation of the photoluminescence mechanism and determination of the configuration content of arabinose isomer solution by fluorescence analysis.

A fluorescence method has been successfully constructed to accurately measure the D/L-Arb configuration content in optical isomers, and its application in ion detection has been expanded, which has greater sensitivity and universality than the circular dichroism (CD) method. It also promotes the study of the emission mechanism of nonconventional luminogens.

A turn-off sensory recognition of Fe3+ and Ru3+ metal ions with novel isoindoline-1,3-dione substituted Schiff base: A detailed theoretical and experimental overview

In this study, we present the synthesis and characterization of a novel isoindoline-1,3-dione-substituted fluorophore, namely 2-[1-benzyl-2-(4-methoxy-phenylimino)-ethyl]-isoindole-1,3-dione (referred to as L), designed for the specific recognition of Fe3+ and Ru3+ metal ions through a fluorescence quenching mechanism. The obtained limit of detection values for Fe3+ and Ru3+ ions were determined to be 0.65 µM and 0.26 µM, respectively. Characterizations of the synthesized fluorophore (L) was achieved through a comprehensive suite of spectroscopic techniques, including 1H and 13C NMR, FT-IR, elemental analyses, and high-resolution mass spectrometry (HRMS). The spectroscopic data unequivocally support the structure and composition of the fluorophore. Fluorescence titration experiments revealed a 1:1 binding stoichiometry between the fluorophore (L) and both Fe3+ and Ru3+ metal ions. Furthermore, we harnessed the easily observable “naked eye” response of the fluorophore-metal ion complexes to develop a rapid, cost-effective, and straightforward on-site trace detection method utilizing paper strips. To gain insights into the complexation mode between the fluorophore (L) and the target metal ions (Fe3+ and Ru3+), we conducted a computational study employing density functional theory (DFT). This computational analysis provided valuable information regarding the structural aspects of the complexes formed. The findings of this research open new avenues for the development of innovative dual chemo-sensors, offering exceptional selectivity and sensitivity for on-site metal ion detection applications. These advancements contribute to the broader field of chemical sensing and pave the way for the creation of highly efficient and reliable detection systems.

A porphyrin-based ion pair receptor constructed through click chemistry

A novel heteroditopic porphyrin-based ion pair receptor with four ureas and four triazoles on the same side of the porphyrin ring was synthesized through click chemistry. This receptor showed high affinity to complex with the ion pairs KCl, NaCl and NH4Cl in 1:1 binding stoichiometries with association constants of 2.48 (± 0.43) × 104, 1.06 (± 0.02) × 105, and 1.97 (± 0.04) × 105 M[Formula: see text], respectively. After complexation with the ion pairs, fluorescence quenching of the porphyrin was observed, which enables its potential applications in ion detection.

WO3-Nanocrystal-Modified Electrodes for Ultra-Sensitive and Selective Detection of Cadmium (Cd2+) Ions

The detection of heavy metal ions is becoming increasingly important for environmental monitoring and personal safety protection. Owing to their large surface area and suitable conductivity, metal oxide semiconductor nanocrystals have been utilized in chemically modified electrodes for the rapid and low-cost detection of heavy metal ions. However, their sensitivity and selectivity for cadmium ion (Cd2+) detection still remains a challenge. Here, a method of ultra-sensitive and selective Cd2+ detection based on WO3-nanocrystal-modified electrodes is proposed and demonstrated. Colloidal WO3 nanocrystals were synthesized via a solvothermal route and then deposited onto a carbon electrode using a spin-coating method, forming the modification layer at room temperature. The WO3-nanocrystal-modified electrodes exhibit a remarkable signal transduction capability that converts Cd2+ adsorption into current output signals. The peak current was linear to the logarithm of the Cd2+ concentration from 1 nM to 10,000 nM when measured using the anodic stripping voltammetry method. The selectivity mechanism was studied and attributed to the high adsorption energy of cadmium on WO3 compared to other heavy metal ions. Employment of WO3 for a high-performance Cd2+-selective electrode opens many opportunities in portable ion-detection applications.

Preparation Methods and Functional Characteristics of Regenerated Keratin-Based Biofilms.

The recycling, development, and application of keratin-containing waste (e.g., hair, wool, feather, and so on) provide an important means to address related environmental pollution and energy shortage issues. The extraction of keratin and the development of keratin-based functional materials are key to solving keratin-containing waste pollution. Keratin-based biofilms are gaining substantial interest due to their excellent characteristics, such as good biocompatibility, high biodegradability, appropriate adsorption, and rich renewable sources, among others. At present, keratin-based biofilms are a good option for various applications, and the development of keratin-based biofilms from keratin-containing waste is considered crucial for sustainable development. In this paper, in order to achieve clean production while maintaining the functional characteristics of natural keratin as much as possible, four important keratin extraction methods-thermal hydrolysis, ultrasonic technology, eco-friendly solvent system, and microbial decomposition-are described, and the characteristics of these four extraction methods are analysed. Next, methods for the preparation of keratin-based biofilms are introduced, including solvent casting, electrospinning, template self-assembly, freeze-drying, and soft lithography methods. Then, the functional properties and application prospects of keratin-based biofilms are discussed. Finally, future research directions related to keratin-based biofilms are proposed. Overall, it can be concluded that the high-value conversion of keratin-containing waste into regenerated keratin-based biofilms has great importance for sustainable development and is highly suggested due to their great potential for use in biomedical materials, optoelectronic devices, and metal ion detection applications. It is hoped that this paper can provide some basic information for the development and application of keratin-based biofilms.

Achieving blue water-dispersed room-temperature phosphorescence of carbonized polymer dots through nano-compositing with mesoporous silica

Stabilizing triplet excited states is important for room temperature phosphorescence (RTP) materials to achieve multifunctional applications in humid environment. However, due to the lack of preparation strategies, the realization of RTP materials in water still faces challenges. Herein, a new design strategy was presented to achieve RTP in water by confining carbonized polymer dots (CPDs) in amino functional mesoporous silica (MSNs-NH2). The as-prepared MSNs-CPDs aqueous dispersion exhibited blue afterglow, lasting more than 3 s to naked eyes. The triplet excited states were protected from non-radiative deactivation by the double-confinement effect including covalent bonding fixation and mesoporous structure confinement. The MSNs-CPDs inherited the structure of MSNs-NH2, so the stability of morphology and properties were superior to CPDs and even most of silica-based CPDs RTP materials. A water-related encryption technique demonstrated the promising application of MSNs-CPDs as smart materials in the field of information security. Besides, the possibility of potential application in ion detection was also explored.

Multicolor carbon dots: Induced by sp2-sp3 hybridized domains and their application in ion detection and WLED

The heteroatom doping to achieve carbon dots has played a crucial part in exploring the fluorescence mechanism of multicolor emissions, which is closely related with the application development of such materials. Herein, a facile method was developed to synthesize three-color CDs via the co-doping of S and N elements with the assistance of ethanol solvent. The achieved CDs mainly emit blue, green and red lights, yet the photoluminescence quantum yields (FLQYs) generally decreases from 54.0% for B-CDs, 11.5% for G-CDs to 8.5% for R-CDs, respectively. Optical and structural characterizations of these CDs show that the variation of sp 2 - sp 3 hybridized domains resulted from the elements doping (S, N) fundamentally determines the color of CDs. The highest FLQYs of B-CDs in all CDs gives it an advantage to detect metal ions, which finds strong quenching only toward Ag + because of the interaction between Ag + and the cores. Likewise, these multicolor CDs attempt to fabricate CDs@PVP composite film emitted white-light as well as a clad material of WLED devices. The results indicate that the correlated color temperatures (CCT) in the ranges of cold and warm white lights can be obtained with different color rendering indexes (CRI) and luminous efficacies. Moreover, CCT and CRI are nearly up to the extremum at the same current value with increasing currents, implying that such CDs are potential as a kind of fluorescent nanomaterial to applicate to WLED device. • A facile strategy to prepare multicolor CDs by means of S and N co-doping. • As-prepared CDs emitted blue, green and red fluorescence respectively. • The B-CDs with high sensitivity for ion detections of Ag +. • Multicolor CDs fabricate the white-light CDs/PVP composite film as well as a clad material of WLED devices.

Engineering white light-emitting diodes with high color rendering index from biomass carbonized polymer dots

Carbonized polymer dots (CPDs) have promise in the fields of sensing, bioimaging, and optoelectronic devices due to their excellent optical properties, favorable biocompatibility, and superior stability. Biomass CPDs present greater advantages in terms of their lack of toxicity, low cost, easy preparation, and feasibility in terms of luminescence-related applications. Here, two kinds of fluorescent CPDs were obtained through the simple hydrothermal method using biomass avocado peel (CPDs-P) and sarcocarp (CPDs-S) as carbon sources. Interestingly, these two biomass CPDs have excellent applications in ion detection and light-emitting diodes (LEDs). Analysis and results show that CPDs-P possess better sensitivity to Fe3+ because they have more oxygen-containing functional groups. After mixing with epoxy resin, warm and cold white LEDs with CIE (Commission Internationale de L 'Eclairage) coordinates (0.38, 0.39) and (0.29, 0.34) were constructed successfully from extremely stable CPDs-P and CPDs-S. The high color rendering index of the prepared white LEDs are 90.47 and 84.54. This study shows that these biomass CPDs are promising materials in sensing and white LEDs illumination.

Computer vision AC-STEM automated image analysis for 2D nanopore applications

Transmission electron microscopy (TEM) has led to important discoveries in atomic imaging and as an atom-by-atom fabrication tool. Using electron beams, atomic structures can be patterned, annealed and crystallized, and nanopores can be drilled in thin membranes. We review current progress in TEM analysis and implement a computer vision nanopore-detection algorithm that achieves a 96% pixelwise precision in TEM images of nanopores in 2D membranes (WS2), and discuss parameter optimization including a variation on the traditional grid search and gradient ascent. Such nanopores have applications in ion detection, water filtration, and DNA sequencing, where ionic conductance through the pore should be concordant with its TEM-measured size. Standard computer vision methods have their advantages as they are intuitive and do not require extensive training data. For completeness, we briefly comment on related machine learning for 2D materials analysis and discuss relevant progress in these fields. Image analysis alongside TEM allows correlated fabrication and analysis done simultaneously in situ to engineer devices at the atomic scale.

Hydrothermal synthesis of N-doped carbon quantum dots and their application in ion-detection and cell-imaging

Carbon quantum dots (CQDs), owing to their characteristic luminescent properties, have become a new favorite in the field of luminescence. They have been widely used in light emitting diode, ion detection, cell-imaging, ect. Herein a facile synthesis method of nitrogen-doped carbon quantum dots (N-CQDs) has been developedviaa one-step hydrothermal of glucose and m-phenylenediamine. The chemical composition, surface functional groups, and crystal structure of so prepared N-CQDs were systematically characterized. The characterizations indicate that nitrogen has been chemically doped in the CQDs and the N-CQDs crystallize in a graphene structure. Photoluminescence (PL) measurements show that the N-CQDs emit strong blue emission under the irradiation of ultraviolet. The emission is excitation-dependent, is resistant to photo bleaching and high ionic strength, and slightly decreases with the increase of temperature. The quantum yield of them is about 17.5%. The PL intensity of N-CQDs quenches linearly with the increase of the concentrations of Fe3+(0.5–1.0 mM) and CrO42−(0.3–0.6 mM), which are a kind of excellent fluorescent probe for the detection of Fe3+ and CrO42−. The quenching mechanism of Fe3+ and CrO42−is verified to be a static quenching mechanism based on inner filter effect. The N-CQDs are also found to be a good cell-imaging reagent of Hela cells.

High fluorescence LaOBr/coumarin organic–inorganic composite nanomaterials for ultra-sensitive Fe3+ sensing, fluorescence imaging and water-based ink anti-counterfeiting applications

Organic–inorganic composite materials have a wide range of applications in ion detection, fluorescence imaging, and ink anti-counterfeiting.

A 3-hydroxythalidomide-based fluorescent probe for detection of fluoride in water sample and bioimaging in living cells

Thalidomide and its derivatives were drawing attentions as an old drug since the cereblon (CRBN) as a thalidomide-binding protein was identified. Herein, we reported its novel application in ion detection for the first time. And a turn-on fluorescent fluoride probe, (4-((tert-butyldimethylsilyl)oxy)-2-(2,6-dioxopiperidin-3- yl)isoindoline-1,3-dione was prepared using a protection-deprotection design strategy taking 3-hyroxythalidomide as parent compound. High selectivity and sensitivity for fluoride ion were observed with significant green fluorescent responses and a remarkable Stokes shift (about 178 nm). The fluorescent change was based on the exited state intramolecular proton transfer mechanism, which had been established by in-situ Fourier transform infrared spectroscopy and 1H NMR techniques. In addition, the probe was successfully applied to detect the fluoride ion in lake water. More importantly, the probe was almost nontoxic to the cultured cells and was applied in bioimaging in living cells.

One step synthesis of N-doped carbon dots/hydroxyapatite:Eu,Gd composite with dual-emissive and solid-state photoluminescence

N-doped carbon dots/hydroxyapatite:Eu,Gd (N-CDs/HA:Eu,Gd) composite was synthesized via a facile one-step hydrothermal route. The obtained composite exhibited porous structure which played key roles in inhibiting the aggregation of N-CDs and enhancing the light absorption. Interestingly, the photoluminescence performance of N-CDs and HA:Eu,Gd was maintained after the one-step in-situ synthesis. Thus, N-CDs/HA:Eu,Gd exhibited dual-emissive and solid state photoluminescence under single wavelength excitation. The unique optical features could endow N-CDs/HA:Eu,Gd potential applications in ion detection and other fields.

Multicolor emissive sulfur, nitrogen co-doped carbon dots and their application in ion detection and solid lighting.

Multicolor emissive carbon dots (CDs) have potential applications in many fields such as photoelectric display, light-emitting devices, and bioimaging. Such CDs by heteroatom doping of nitrogen elements assisted with various solvents has achieved recently, yet generally low efficiency in red-light region. Herein, we developed a facile route to synthesize multicolor-emissive CDs governed by a solvothermal method of tetrahydrofuran solvent. The maximum emission locates at 432, 510, and 584nm with the absolute FL QYs up to 21.1%, 11.0%, and 55.4% for selected B-CDs, G-CDs, and YG-CDs, respectively. By means of the analysis on their PL spectra, fluorescence lifetimes, and microstructures, the different graphitic degrees and surface states formed under the participation of S and N elements in as-prepared CDs determine the fluorescent color, and large sp2-conjugated domains within the YR-CDs is closely related to high QY. They, likewise, endow the YR-CDs with high sensitivity for ion detections of Ag+ and Fe3+, which was further illustrated to have different quenching mechanisms each other due to the affinity interaction with different surface groups of the CDs. High PL QYs of these CDs emission are beneficial to application in solid lighting, phosphors dried by these CDs solutions were mixed with PVP water solution to fabricate CDs/PVP films. The films exhibited stable fluorescence, and three phosphors were also mixed together in proportion to obtain white-light film with a CIE coordinates of (0.34, 0.34), which demonstrates that these CDs are potentially fluorescent nanomaterial in the solid-state lighting field.

Synthesis of Silane-Based Poly(thioether) via Successive Click Reaction and Their Applications in Ion Detection and Cell Imaging.

A series of poly(thioether)s containing silicon atom with unconventional fluorescence were synthesized via successive thiol click reaction at room temperature. Although rigid π-conjugated structure did not exist in the polymer chain, the poly(thioether)s exhibited excellent fluorescent properties in solutions and showed visible blue fluorescence in living cells. The strong blue fluorescence can be attributed to the aggregation of lone pair electron of heteroatom and coordination between heteroatom and Si atom. In addition, the responsiveness of poly(thioether) to metal ions suggested that the selectivity of poly(thioether) to Fe3+ ion could be enhanced by end-modifying with different sulfhydryl compounds. This study further explored their application in cell imaging and studied their responsiveness to Fe3+ in living cells. It is expected that the described synthetic route could be extended to synthesize novel poly(thioether)s with superior optical properties. Their application in cell imaging and ion detection will broaden the range of application of poly(thioether)s.

Enhancing Potentiometric Response Using Modified Ion Sensitive Transistor

High sensitivity, high selectivity, reproducibility and quick response are of prime importance for ion detection in various applications. In this respect, electrochemical detection is the best technique as compared to the traditional flame photometry, ion chromatography and surface plasmon resonance [1]. In an ion sensitive field effect transistor (ISFET), directly exposing the gate oxide of field effect transistor (FET) to an ionic solution causes ion penetration into the oxide layer. This is reflected in I-V characteristics that show voltage-dependent hysteresis due to ion penetration [2]. Extended gate field effect transistor (EGFET) shows great potential over the usual methods of ISFETs or ion sensitive electrode (ISE). EGFET effectively improves the reliability by separating the sensor and the transducer, associating the two by interconnect. It also provides a wide range of detection with possibility for device miniaturization and is extremely easy to fabricate [3]. In this work, we present a novel combination of solid-state ISE and FET integrated on same platform. Thus, creating an EGFET. We have built an electrochemical sensing unit comprised of all solid-state electrodes, an Ag/AgCl reference electrode and ionophore coated gold electrode. Unlike any of the earlier reports, all the electrodes are integrated with a FET in a single plane of printed circuit board (PCB), hence mitigating the issues of separate wire bonding or external connection between the sensing element and the transducer by using PCB traces [2]. In this work, we demonstrate for the first time, the use of ISE in EGFET configuration without degrading the linearity and sensitivity due to the external voltage bias. Potentiometric measurement on our potassium ion (K+) ISE shows near Nernstian limit sensitivity (49 mV/decade), low concentration for the limit of detection (10−6 M), and linearity over a large range of detection (10−4 M to 1 M). We demonstrate a simple approach to develop an array of miniaturized two terminal planar solid state electrode device consisting of an ion selective membrane (ISM) on gold as the working electrode (WE) and solid state silver/silver chloride (Ag/AgCl) as the reference electrode (RE), both clamped to the metal contacts of the FET. 18-crown-6 (ionophore) has been utilized in ion selective membrane on WE to achieve high selectivity towards K+ ions [4]. Highly stable and low cost Ag/AgCl electrode with the drift potential of less than 2mV is used as pseudo RE [5]. The principle mechanism behind our sensing approach is transduction of ionic stimulus into electrical signal. Concentration dependent change in the ISM potential at WE/electrolyte interface prompts a corresponding adjustment in overall gate potential, thus modifying the charge transport in FET. Sensitivity and linearity of potassium ion (K+) ISE is determined by potentiometric measurements at several concentrations ranging from 1M to 10−6 M. The electrodes are reusable after each measurement by simply rinsing it in deionized water. Our study shows that voltage biasing does not affect the electromotive force (Vcell). This makes the device suitable and robust for EGFET configuration to enhance the sensitivity for the ion detection applications. Two-fold increase in the sensitivity (100mV/decade, much higher than reported values ion selective electrodes [3,6]) is observed in EGFET configuration. The innovative approach used in our solid-state K+ EGFET has great potential to propel the future in micro-devices with commercialized product for the applications of clinical investigation, environmental and agricultural field. Our methodology represents a handy procedure by using facile fabrication technique for the accomplishment of multipurpose, versatile, and cost-effective ion sensing devices. Reference Dorothee Grieshaber, et al. “Electrochemical Biosensors - Sensor Principles and Architectures”, Sensors, Mar 2008.Q. Li, et al. "Stable Thin-Film Reference Electrode on Plastic Substrate for All-Solid-State Ion-Sensitive Field-Effect Transistor Sensing System," IEEE Electron Device Letters, Oct 2017.Salzitsa Anastasova, et al. “Multi-parametric rigid and flexible, low-cost, disposable sensing platforms for biomedical applications”, Biosensors and Bioelectronics, Apr 2018.Sunita Kumbhat, et al. “A potassium-selective electrochemical sensor based on crown-ether functionalized self assembled monolayer”, Journal of Electroanalytical Chemistry, Jan 2018.Despina Moschou, et al. “Surface and Electrical Characterization of Ag/AgCl Pseudo-Reference Electrodes Manufactured with Commercially Available PCB Technologies”, Sensors, July 2015.He Q, et al. “Enabling Inkjet Printed Graphene for Ion Selective Electrodes with Postprint Thermal Annealing”, ACS Applied Materials & Interfaces, Feb 2017. Figure 1

Development of Microchip Electrophoresis and Its Applications in Ion Detection

Abstract Microchip electrophoresis is emerging as a highly promising method due to its portability and fast analysis with a minimum number of analytes. In this review, recent developments in microchip electrophoresis were described with discussions on the structures, materials, processing technologies, surface modification, experimental methods, and applications in ion detection. The existing issues and prospects of future studies were discussed as well.

Novel single-cell mega-size chambers for electrochemical etching of panorama position-sensitive polycarbonate ion image detectors.

A novel development is made here by inventing panorama single-cell mega-size electrochemical etching (MS-ECE) chamber systems for processing panorama position-sensitive mega-size polycarbonate ion image detectors (MS-PCIDs) of potential for many neutron and ion detection applications in particular hydrogen ions or proton tracks and images detected for the first time in polycarbonates in this study. The MS-PCID is simply a large polycarbonate sheet of a desired size. The single-cell MS-ECE invented consists of two large equally sized transparent Plexiglas sheets as chamber walls holding a MS-PCID and the ECE chamber components tightly together. One wall has a large flat stainless steel electrode (dry cell) attached to it which is directly in contact with the MS-PCID and the other wall has a rod electrode with two holes to facilitate feeding and draining out the etching solution from the wet cell. A silicon rubber washer plays the role of the wet cell to hold the etchant and the electrical insulator to isolate the dry cell from the wet cell. A simple 50 Hz-HV home-made generator provides an adequate field strength through the two electrodes across the MS-ECE chamber. Two panorama single-cell MS-ECE chamber systems (circular and rectangular shapes) constructed were efficiently applied to processing the MS-PCIDs for 4π ion emission image detection of different gases in particular hydrogen ions or protons in a 3.5 kJ plasma focus device (PFD as uniquely observed by the unaided eyes). The panorama MS-PCID/MS-ECE image detection systems invented are novel with high potential for many applications in particular as applied to 4π panorama ion emission angular distribution image detection studies in PFD space, some results of which are presented and discussed.

Fluorescent and colorimetric sensor for Cu2+ ion based on formaldehyde modified hyperbranched polyethylenimine capped gold nanoparticles

In this paper, we propose a fluorescent and colorimetric sensor for Cu2+ ion based on formaldehyde modified hyperbranched polyethylenimine capped gold nanoparticles (F-hPEI Au NPs). The fluorescent sensor is prepared by one-pot synthesis, of which the fluorescence intensity could be quenched by Cu2+ ion. The response behavior of the sensor is dependent on the pH value of the solution. At pH 4.0, the sensor exhibits a linear response for Cu2+ ion over a wide concentration range of 0.15μM–23μM. The detection limit for the sensor is estimated to be 77nM (S/N=3), and the precision for five replication detections of 2.0μM Cu2+ ion is 4.7% (relative standard deviation). Both the color and fluorescence intensity of the sensor change obviously and could be observed with the naked eyes when there is continuous addition of Cu2+ ion. The fluorescence intensity of quenched sensor could be recovered by EDTA, which provides a potential method to regenerate the sensor. Furthermore, the sensor shows satisfying reliability and accuracy in practical Cu2+ ion detection applications.