Calcium Ion-selective Electrode Research Articles

Enhanced Performance of Calcium-Ion Selective Electrode Based on Chitosan/MXene/ZnO Modification

Enhanced Performance of Calcium-Ion Selective Electrode Based on Chitosan/MXene/ZnO Modification

Highly Stable Solid Contact Calcium Ion-Selective Electrodes: Rapid Ion-Electron Transduction Triggered by Lipophilic Anions Participating in Redox Reactions of CunS Nanoflowers.

Solid contact (SC) calcium ion-selective electrodes (Ca2+-ISEs) have been widely applied in the analysis of water quality and body fluids by virtue of the unique advantages of easy operation and rapid response. However, the potential drift during the long-term stability test hinders their further practical applications. Designing novel redox SC layers with large capacitance and high hydrophobicity is a promising approach to stabilize the potential stability, meanwhile, exploring the transduction mechanism is also of great guiding significance for the precise design of SC layer materials. Herein, flower-like copper sulfide (CunS-50) composed of nanosheets is meticulously designed as the redox SC layer by modification with the surfactant (CTAB). The CunS-50-based Ca2+-ISE (CunS-50/Ca2+-ISE) demonstrates a near-Nernstian slope of 28.23 mV/dec for Ca2+ in a wide activity linear range of 10-7 to 10-1 M, with a low detection limit of 3.16 × 10-8 M. CunS-50/Ca2+-ISE possesses an extremely low potential drift of only 1.23 ± 0.13 μV/h in the long-term potential stability test. Notably, X-ray absorption fine-structure (XAFS) spectra and electrochemical experiments are adopted to elucidate the transduction mechanism that the lipophilic anion (TFPB-) participates in the redox reaction of CunS-50 at the solid-solid interface of ion-selective membrane (ISM) and redox inorganic SC layer (CunS-50), thereby promoting the generation of free electrons to accelerate ion-electron transduction. This work provides an in-depth comprehension of the transduction mechanism of the potentiometric response and an effective strategy for designing redox materials of ion-electron transduction triggered by lipophilic anions.

Mechanical Properties and Ion Release from Fibre-Reinforced Glass Ionomer Cement.

The aim of this study was to compare the mechanical properties and ion release from a commercially available resin-modified glass ionomer cement to a formulation reinforced by the addition of short glass fibres at various percentages. Methods: Three experimental groups were prepared by adding a mass ratio of 10%, 15% and 20% of short glass fibres to the powder portion of the cement from a capsule (GC Fuji II LC), while the control group contained no fibres. Microhardness (n = 12), fracture toughness, and flexural, compressive and diametral tensile strength (n = 8) were evaluated. To study ion release, readings were obtained utilising fluoro-selective and calcium-selective electrodes after 24 h, 7 days and 30 days (n = 12). The spatial distribution of fibres within the material was evaluated through scanning electron microscopy. The data were analysed using one-way ANOVA with a Bonferroni adjustment. Results: The findings suggest that elevating fibre weight ratios to 20 wt% results in improved mechanical properties (p < 0.05) in microhardness, flexural strength, diametral tensile strength and fracture toughness. In terms of ion release, a statistically significant difference (p < 0.001) was observed between the groups at the conclusion of 24 h and 7 days, when the fluoride release was much higher in the control group. However, after 30 days, no significant distinction among the groups was identified (p > 0.05). Regarding calcium release, no statistically significant differences were observed among the groups at any of the evaluated time points (p > 0.05). SEM showed the fibres were homogeneously incorporated into the cement in all experimental groups. Conclusions: Resin-modified glass ionomer enhanced with short glass fibres at a weight loading of 20% showcased the most favourable mechanical properties while concurrently maintaining the ability to release fluoride and calcium after a 30-day period.

Carbon-Based Transducers for Solid-Contact Calcium Ion-Selective Electrodes: Mesopore and Nitrogen-Doping Effects.

Solid-contact ion-selective electrodes (SC-ISEs) exhibit great potential in the detection of routine and portable ions which rely on solid-contact (SC) materials for the transduction of ions to electron signals. Carbon-based materials are state-of-the-art SC transducers due to their high electrical double-layer (EDL) capacitance and hydrophobicity. However, researchers have long searched for ways to enhance the interfacial capacitance in order to improve the potential stability. Herein, three representative carbon-based SC materials including nitrogen-doped mesoporous carbon (NMC), reduced graphene oxide (RGO), and carbon nanotubes (CNT) were compared. The results disclose that the NMC has the highest EDL capacitance owing to its mesopore structure and N-doping while maintaining high hydrophobicity so that no obvious water-layer effect was observed. The Ca2+-SC-ISEs based on the SC of NMC exhibited high potential stability compared with RGO and CNT. This work offers a guideline for the development of carbon-material-based SC-ISEs through mesoporous and N-doping engineering to improve the interfacial capacitance. The developed NMC-based solid-contact Ca2+-SC-ISE exhibited a Nernstian slope of 26.3 ± 3.1 mV dec−1 ranging from 10 μM to 0.1 M with a detection limit of 3.2 μM. Finally, a practical application using NMC-based SC-ISEs was demonstrated through Ca2+ ion analysis in mineral water and soil leaching solutions.

Development and characterization of ion-releasing fiber-reinforced flowable composite

ObjectiveThis study aimed to develop and characterize an ion-releasing experimental fiber-reinforced flowable composite (Bio-SFRC) and dentin treatment solution made of poly(acrylic acid) (PAA) with a high molecular weight. In addition we also evaluated the interface structure and mineralization potential between the Bio-SFRC and dentin. MethodsSome mechanical properties (flexural properties and fracture toughness) of Bio-SFRC in comparison with commercial inert (G-aenial Flo X) and ion-releasing materials (ACTIVA-BioActive Base/Liner and Fuji II LC) were assessed (n = 8/group). Calcium-release at different time-points was measured during the first six weeks by using a calcium-ion selective electrode. Surface analysis of composites after being stored in simulated body fluid (SBF) was investigated by using SEM/EDS. Dentin disks (n = 50) were prepared from extracted sound teeth and demineralization was simulated by acid etching. SEM/EDS was used to evaluate the microstructure of dentin on the top surface and at interface with composites after being stored in SBF. ResultsBio-SFRC showed higher fracture toughness (1.6 MPa m1/2) (p < 0.05) compared to Flo X (1.2 MPa m1/2), ACTIVA (1 MPa m1/2) and Fuji II LC (0.8 MPa m1/2). Accumulative calcium release after six weeks from Bio-SFRC (15 mg/l) was higher than other tested ion-releasing materials (≈ 6 mg/l). Mineralization was clearly seen at the interface between treated dentin and Bio-SFRC. None of the commercial tested materials showed signs of mineralization at the interface and dentinal tubules remained open.Significance.Developing such reinforced ion-releasing flowable composite and PAA solution might offer the potential for mineralization at the interface and inside the organic matrix of demineralized dentin.

Polymeric Membrane Marine Sensors with a Regenerable Antibiofouling Coating Based on Surface Modification of a Dual-Functionalized Magnetic Composite.

Environmentally compatible polymeric membrane marine sensors with excellent antiadhesive and antibacterial properties have recently been developed. However, the regeneration abilities of these sensors after fouling have rarely been investigated. Herein, a novel strategy for preparation of a regenerable antibiofouling coating via surface modification of a dual-functionalized magnetic composite is proposed. A zwitterionic polymer (i.e., poly(sulfobetaine methacrylate)) and a quaternary ammonium compound (i.e., 3-trimethoxysilylpropyl octadecyldimethyl ammonium chloride) are coated on the surface of Fe3O4 microspheres for antiadhesion and bacterial inactivation, respectively. The antifouling magnetic composite can readily be modified on the sensor's surface via the magnetically assisted self-assembly technology. Using a polymeric membrane calcium ion-selective electrode as a model sensor, the protection layer-coated electrode shows the markedly improved antibiofouling activities as compared to the unmodified sensor. More importantly, by altering the direction of the external magnetic field, the antifouling coating can easily be removed after fouling along with the removal of the adsorbed bacterial cells from the electrode's surface, which is followed by re-modifying a fresh coating for regeneration of the antifouling electrode. The proposed methodology for fabrication of a regenerable antibiofouling coating is promising to improve the durability of a marine sensor.

Solid-contact polymeric membrane ion-selective electrodes based on electrodeposited NiCo2S4 nanosheet arrays

In situ growth of quasi-superhydrophobic porous NiCo2S4 nanosheet arrays with a one-step electrodeposition method was provided. A calcium ion-selective electrodes (Ca2+-ISE) was subsequently constructed by using the prepared NiCo2S4 as a solid contact layer. The proposed Ca2+-ISE exhibits a good Nernstian slope of 30.7 ± 0.3 mV/dec and a detection limit of 1.6 × 10−7 M. Due to the large redox capacitance of 1.8 mF, the Ca2+-ISE based on NiCo2S4 nanosheet arrays shows a high potential stability of 1.9 ± 0.5 μV/h over 90 h. Excellent reproducibilities for the NiCo2S4-based Ca2+-ISEs can be obtained with the single batch and batch-to-batch E° standard deviations of 0.3 (n = 6) and 0.7 mV (n = 5), respectively. The NiCo2S4 nanosheet arrays have a large contact angle of 148 ± 1.4°, which effectively suppresses the formation of a water layer at the sensing membrane/NiCo2S4 interface.

Carbon composite thermoplastic electrodes integrated with mini-printed circuit board for wireless detection of calcium ions.

Here, a smartphone-based portable sensing system is developed for real-time detection of Ca2+ ions in a variety of biofluids. A solid-contact calcium-selective electrode (Ca2+-ISE) consisting of anion-selective membrane (ISM), carbon black nanomaterial and polystyrene-graphite nanoplatelets as a solid contact was fabricated. The polyvinylchloride (PVC)-based ISM was optimized using different plasticizers and ion-exchangers. Under optimized conditions, the solid contacts were electrochemically characterized byelectrochemical impedance spectroscopy(EIS), chronopotentiometric andpotentiometric measurements. The Ca2+-ISE showed a Nernst response with a slope of 31.2 ± 0.6mV/decade in the concentration range from 0.1M to 10-4M Ca2+ with a limit of detection (LOD) of 1.0 × 10-5M. In addition, the ISEs exhibited good selectivity to Ca2+ ions over various interfering electrolytes and metabolites. The Ca2+-ISEs were applied in human urine and, artificial serum and cerebrospinal fluid samples. The ISEs showed good recoveries between 90 and 105%, indicating potential applicability of these electrodes in biological fluids. The portable lab-made potentiometer provides wireless data signaling and transmission to a smartphone and final Ca2+ concentration display due to its customized software. Therefore, the developed smartphone-based sensing platform offers low cost (< $25), rapid, user-friendly detection of Ca2+ especially in resource-limited areas.

Automated regional citrate anticoagulation based on online monitoring of ionized calcium concentration: Proof of concept.

Regional citrate anticoagulation (RCA), a complex and effective technique, is recommended as the anticoagulation of choice for continuous renal replacement therapy. One of its key objectives is to keep the ionized calcium in the targeted range. In this study, we aimed to develop an automated RCA based on online monitoring of the ionized calcium concentration and closed-loop feedback. We constructed calcium-selective electrodes with liquid inner contact, which measured a potentiometric signal as the output. We tested the responses, stability, and selectivity of the electrodes in flowing fluid containing calcium chloride. We compared the measurement accuracy between the electrodes and an i-STAT system in vivo. Moreover, we established closed-loop feedback using a proportional-integral-derivative controller model. We performed simulated automated RCA both in vivo and in vitro. The electrode gave a Nernstian response to the variation of ionized calcium concentration. It showed high stability and a relatively short response time. Changes in the fluid flow rate, solution PH, and addition of metal ions including Mg2+ and K+ did not interfere with the measurements of ionized calcium. These measurements in whole blood by the electrode were very close to those assessed by the i-STAT system. The feedback control system responded quickly to an abnormal ionized calcium concentration and regulated the infusion rates of calcium or citrate to maintain the concentration of ionized calcium within the targeted range. We successfully trialed automated RCA, which may help simplify the complexities of RCA in the future.

A novel inorganic redox buffer of r-GO/Ag@AgCl/TMMCl utilized as an effective ion-to-electron transducer for a solid contact calcium ion-selective electrode

The Ag@AgCl/1-tetradecyl-3-methylimidazolium chloride (TMMCl) reported as an inorganic redox buffer for solid contact ion-selective electrodes (SC-ISEs) suffers from minimized specific area for an aggregation of Ag nanoparticles and decreased electron transfer for a presence of AgCl coating. Herein, a novel optimized inorganic redox buffer of r-GO/Ag@AgCl/TMMCl with improved capacitance and electron transfer behaving well as an effective ion-to-electron transducer for a SC-Ca2+-ISE has been highlighted. With reduced graphene oxide (r-GO) introduced as a substrate, the produced Ag nanoparticles as well as the subsequently synthesized core-shell Ag@AgCl nanomaterials display high dispersity with diameters decreased to 10–40 nm. Cyclic voltammetry with better redox reversibility and higher areas for the r-GO/Ag@AgCl/TMMCl verifies its improved redox capacitance and acceleration in electron transfer. Taking advantage of the r-GO/Ag@AgCl/TMMCl, the fabricated SC-Ca2+-ISE exhibits a near Nernst slope about 28.5 mV/dacade between potentials to Ca2+ concentrations ranging from 10−6 to 10−3M. Additionally, a diminished Rbc and Rct as well as an increased capacitance are also exemplified by the EIS and chronopotentiometric techniques, which would ensure a fast and stable potentiometric response. Moreover, the fabricated SC-Ca2+-ISE displays a good selectivity and water layer resistance. Thanks to the increased redox capacitance of the r-GO/Ag@AgCl/TMMCl, the fabricated SC-Ca2+-ISE demonstrates stable potentiometric response and good E0 reproducibility.

Effect of topically applied silver compounds on the demineralisation of hydroxyapatite

ObjectivesThis study investigates the demineralization inhibitory mechanisms of AgNO3, AgF and silver diamine fluoride (SDF) using a previously used hydroxyapatite (HAP) caries demineralization model system. MethodsHAP discs were allocated into three groups (n = 3) and immersed in demineralization solution (buffered pH 4.0, 0.1 mol/L acetic acid) for 4 h. Each disc was treated topically with either 3.16 M AgNO3, 3.16 M AgF or 3.16 M SDF using a micro-brush. The discs were then demineralized for a further 4 h. Calcium, silver, and fluoride ion selective electrodes (ISEs) were used to monitor the changes in each ion concentration at 1 min intervals throughout. Demineralization inhibition was calculated as the percentage reduction in the rate of calcium ion loss from HAP (PRCLHAP). Characterization of similarly treated HAP powder was carried out with Magic Angle Spinning-Nuclear Magnetic Resonance ResultsThe mean PRCLHAP for each treatment group was; AgF (72.3 + 4.8%), SDF (69.7 + 5.3%) and AgNO3 (14.9 + 2.7%). Ag3PO4 was detected in all HAP powders. CaF2 and fluorohydroxyapatite (FHA) were detected only in powders treated with either AgF or SDF.The demineralization inhibitory efficacy of topically applied AgNO3 results from the formation of a Ag3PO4 barrier. Whereas, the demineralization inhibitory efficacy of topically applied AgF, and SDF, results from the formation of a barrier composed of Ag3PO4, CaF2, and FHA. SignificanceIn addition to their anti-microbial properties, clinical topical application of silver compounds for caries preventative treatment is due to their ability to form acid-resistant barriers composed of silver phosphate. When fluoride is present, this barrier also contains CaF2 and FHA, additionally protecting the mineral.

A Study Focusing on the Preparation and Application of New-mode Electrode Materials for Water Hardness Measurement

This paper aimed to study the calcium ion selective electrode, based on using PVC as the electrode carrier and didecyl calcium phosphate which was synthesized from decanol, phosphorus oxytrichloride, pyridine and calcium chloride as the electroactive substance. This paper mainly focused on the study and the fabrication process of both the electrode diaphragm and electrode, with conducting the performance test of the newly developed electrode. The results showed that the response time of the developed water hardness sensor was 2-5 s, which had good response characteristics and was suitable for fast and portable testing of water hardness in environmental testing. There was no significant difference between this water hardness sensor method and the national standard method. When the water temperature varies between 10 and 60 Centigrade, the influence of temperature on the data of the water hardness sensor was very small, and the water hardness sensor had good stability to test the temperature change.

Effect of molecular structure of maleic anhydride, fumaric acid – Isopentenyl polyoxyethylene ether based polycarboxylate superplasticizer on its properties in cement pastes

Polycarboxylate ether (PCE) superplasticizers with different molecular structure were synthesized by copolymerizing macro-monomer with cis-butenedioic anhydride (MAH) and trans-1,2-ethenedicarboxylic acid (FA). Gel permeation chromatography, specific charge density, Fourier transform infrared spectroscopy, 1H and 13C nuclear magnetic resonance were used to characterize these co-polymers. Their Ca2+ binding capacity, adsorption behaviors, retardation effects and dispersion efficiency were investigated by the calcium-ion selective electrode, total organic carbon, X-ray Photoelectron Spectroscopy, zeta potential, calorimetry measurements, mini-cone and rheological tests. Results indicated that PCE containing more FA possesses the higher density of –COO– groups, due to the higher reactivity of FA than MAH. The high density of –COO– groups in PCEs significantly affects their adsorption behaviors, retardation, and dispersion of cement pastes. Intermolecular chelation between –COO– groups and Ca2+ is dominated for FA-PCE, while the main coordination modes between –COO– in MAH-PCE and Ca2+ are intramolecular chelation owing to more adjacently distributed –COO– groups. FA-PCE exhibits larger adsorption amount and thicker adsorption layer compared with MAH-PCE. Hence, the FA-PCE demonstrated stronger dispersion efficiency, with which the cement pastes showed excellent flowability and rheological properties, correspondingly.

Calcium ion-selective electrode based on the facile synthesis of CuO over Cu wires

Calcium ion-selective electrode based on the facile synthesis of CuO over Cu wires

Enhancing the Oil-Fouling Resistance of Polymeric Membrane Ion-Selective Electrodes by Surface Modification of a Zwitterionic Polymer-Based Oleophobic Self-Cleaning Coating

Due to the frequent oil spill accidents and pollution of industrial oily wastewater, oil fouling has become a great challenge to polymeric membrane ion-selective electrodes (ISEs) for applications in oil-contaminated areas. Herein, a simple approach is proposed to enhance the oil-fouling resistance of polymeric membrane ISEs by surface modification of a zwitterionic polymer-based underwater oleophobic coating. As a proof-of-concept, a classical poly(vinyl chloride) membrane-based calcium ion-selective electrode (Ca2+-ISE) is chosen as a model sensor. The zwitterionic polymer-based coating can be readily modified on the sensor's surface by immersion of the electrode into a mixture solution of dopamine and a zwitterionic acrylate monomer (i.e., sulfobetaine methacrylate, SBMA). The formed poly(SBMA) (PSBMA) coating alters the oleophilic membrane surface to an oleophobic one, which endows the surface with excellent self-cleaning properties without loss of the sensor's analytical performance. Compared to the pristine Ca2+-ISE, the PSBMA-modified Ca2+-ISE exhibits an improved analytical stability when exposed to oil-containing wastewater. The proposed approach can be explored to enhance the oil-fouling resistance of other polymeric membrane-based electrochemical sensors for use in the oil-polluted environment.

Investigations of mechanism of Ca2+ adsorption on silica and alumina based on Ca-ISE monitoring, potentiometric titration, electrokinetic measurements and surface complexation modeling

Research on Ca2+ adsorption onto the mineral surface is of significant importance with regard to geochemical processes. Sverjensky (Geochim Cosmochim Acta 70(10), 2427–2453, 2006) assumed that alkaline earths form two types of surface species on oxides: tetranuclear (> SOH)2(> SO−)2_M(OH)+ and mononuclear > SO−_M(OH)+. To look into the above assumption we investigated calcium adsorption on SiO2 and Al2O3 because they are the most widespread minerals in the environment. We have determined the proton surface charge, electrokinetic potential and metal adsorption as a function of pH. The Ca2+ uptake and concentration in the system were monitored by the calcium ion-selective electrode (Ca-ISE). The Ca-ISE measurements indicated a similar affinity of Ca2+ for both materials despite their differently charged surface, negative for silica and mainly positive for alumina. This may suggest that simple electrostatic interactions are not the primary driving force for calcium adsorption, and that solvation of calcium ions at the surface may be crucial. We have analyzed our experimental data using the 2-pK triple-layer model (2-pK TLM). Three calcium complexes on the mineral surface were reported. Two of them were the same for both oxides, i.e. the tetranuclear (> SOH)2(> SO−)2_Ca2+ and mononuclear complexes > SO−_CaOH+. Additionally, minor contribution from >SOH…Ca2+ for silica was assumed. In the case of Al2O3 the hydrolyzed tetranuclear complexes (> SOH)2(> SO−)2_CaOH+ at pH > 7.5 occurred based on the modeling results. Two types of surface complexes suggested by Sverjensky allowed for the correct description of proton and calcium uptake for alumina. However, the electrokinetic data excluded hydrolyzed tetranuclear surface species for this oxide.

The effect of different fluoride varnishes on the release of calcium ions from hydroxyapatite discs: An ion-selective electrodes study

Introduction: Recently, various modes of fluoride varnishes have evolved, each with its own recommended concentration, potentially active ingredients, and flavour, leading to a claim of additional preventive benefits. Differences in fluoride release patterns can potentially enhance or reduce the efficacy of fluoride varnishes. Numerous clinical trials have proven its ability in preventing and arresting dental caries. This study mainly focused on the investigations of the apatite demineralisation process under the effect of different fluoride varnishes by ion-selective electrodes (ISE), in an attempt to comprehend their mechanism in anti-caries. Methods: Four different fluoride varnishes (Fluor Protector S, Duraphat, ClinPro White, MI Varnish) were used to measure their effect on the demineralisation process of the hydroxyapatite (HAP) discs in 60ml pH 4.0 acetic solutions. The HAP discs were treated with these varnishes after 4-hours demineralisation and then immersed back into the same solutions for further demineralisation to observe the effect of the varnishes. Throughout the experiment, the calcium ISE was used to monitor the rate of calcium concentration. Results: The result demonstrated that ClinPro White varnish resulted in the most significant inhibition of demineralisation and signs of probable remineralisation throughout the experiment. Other fluoride varnishes treatment showed the ability to inhibit demineralisation. However, the rate of calcium dissolution was not significantly different from different varnishes. The fact that the ClinPro White showed evidence of remineralisation might be associated with the fact that the varnish contained a source of calcium and phosphate. Conclusion: The fluoride varnishes treatment is shown to be effective in inhibiting the demineralisation of apatite regardless of the difference in fluoride concentration and potentially active ingredients incorporated in some of the fluoride varnishes.

Nitrogen-Doped Porous Carbon Derived from Zeolitic Imidazolate Framework-67 Strung into Necklace with Carbon Nanotubes for the Detection of Calcium at Ultralow Level

Zeolitic imidazolate frameworks (ZIFs) are vital branch of metal-organic frameworks (MOFs) that have attracted plentiful interest due to their variable structures and easy-synthesis characteristics. Research on ZIFs and their derived nanostructures for electrochemical applications is increasing. Nitrogen-doped porous carbons (NPCs) derived from ZIFs have been widely used in electrochemical catalysis and energy storage. However, there is limited information on their use as potentiometric sensors. In the present work, ZIFs-derived NPCs strung into necklace with multi-walled carbon nanotube (MWCNT/NPC) were synthesized and used as an effective solid contact for calcium ion-selective electrode (ISE). The synthesized composites showed good uniformity, a high capacitance and improved electrical conductivity. Sensors fabricated from these composites displayed a very short response time (2–3 s) and a low detection limit (1.49 nM) for calcium. When the amount of calcium in untreated milk was analysed by the sensor, sensitive and accurate results were obtained. Additionally, studies of stability, reproducibility, and selectivity also confirmed that the prepared MWCNT/NPC composite was an efficient transducer, and ideal for a potentiometric sensor. This study advances the development of ISE-based sensors by improving the detection limit and provides a technical pathway for directly detecting calcium in untreated milk.

The preparation of a fine tip calcium ion selective electrode

The preparation of a fine tip calcium ion selective electrode

A solid-contact Ca2+-selective electrode based on an inorganic redox buffer of Ag@AgCl/1-tetradecyl-3-methylimidazolium chloride as ion-to-electron transducer

For construction of solid-contact ion-selective electrodes (SC-ISEs), ion-to-electron transducers based on the redox capacitance transduction mechanism are currently restricted to organic materials. Exploring inorganic nanomaterials with high redox buffer capacities as intermediate layers for SC-ISEs would offer another alternative. Herein, a solid-contact calcium ion-selective electrode (SC–Ca2+-ISE) with a new inorganic redox buffer-Ag@AgCl/1-tetradecyl-3-methylimidazolium chloride (TMMCl) as the ion-to-electron transducer is presented. In this system, the predominant component core-shell Ag@AgCl nanoparticles with diameters ranging from 30 to 100 nm can be prepared through a two-step process. An ionic liquid TMMCl is used to offer a source of free Cl−. The developed SC-Ca2+-ISE exhibits a near Nernstian slope of 28.3 mV/decade for Ca2+ in the range of 10−6 - 10−2 M. By using of the inorganic redox buffer, the SC-Ca2+-ISE has a smaller impedance and higher capacitance than the coated-wire electrode, which guarantees a stable potential response. Additionally, the proposed SC-Ca2+-ISE shows excellent resistances to interferences of light, O2 and CO2, with a reduced water layer formed between the ion-selective membrane and the underlying solid contact. The developed inorganic redox buffer of Ag@AgCl/TMMCl can be effectively used as a new ion-to-electron transducer for construction of solid contact ISEs.