Electrogenerated Chemiluminescence Sensor Based on Tris(2,2′‐bipyridine)ruthenium(II)‐Immobilized Natural Clay and Ionic Liquid

A novel electrogenerated chemiluminescence (ECL) sensor based on natural clay and ionic liquid was fabricated. Tris(2,2′‐bipyridine)ruthenium(II) (Ru(bpy)₃²⁺) was immobilized on natural clay surface through simple adsorption. An ECL sensor was prepared by mixing Ru(bpy)₃²⁺‐incorporated clay, graphite powder and an ionic liquid (1‐butyl‐3‐methylimidazolium hexafluorophosphate) as the binder. The electrochemical behavior and ECL of the immobilized Ru(bpy)₃²⁺ was investigated. It was observed that the ECL of immobilized Ru(bpy)₃²⁺ was activated by the ionic liquid. The proposed ECL sensor showed high sensitivity to tri‐n‐propylamine (TPrA) and the detection limit was found to be 20 pM. In addition, the ECL sensor displayed good stability for TPrA detection and long‐term storage stability.     

A Solid‐State Electrochemiluminescence Immunosensor Based on MWCNTs‐Nafion and Ru(bpy)32+/Nano‐Pt Nanocomposites for Detection of α‐Fetoprotein

A approach was successfully employed for constructing a solid‐state electrochemiluminescence (ECL) immunosensor by layer‐by‐layer self‐assembly of multiwall carbon nanotubes (MWCNTs)‐Nafion composite film, Ru(bpy)₃²⁺/nano‐Pt aggregates (Ru‐PtNPs) and Pt nanoparticles (PtNPs). The influence of Pt nanoparticles on the ECL intensity was quantitatively evaluated by calculating the electroactive surface area of different electrodes with or without PtNPs to immobilize Ru(bpy)₃²⁺. The principle of ECL detection for target α‐fetoprotein antigen (AFP) was based on the increment of resistance after immunoreaction, which led to a decrease in ECL intensity. The linear response range was 0.01–10 ng mL^?1 with the detection limit of 3.3 pg mL^?1. The immunosensor exhibited advantages of simple preparation and operation, high sensitivity and good selectivity.     

Amine‐Rich Nitrogen‐Doped Carbon Nanodots as a Platform for Self‐Enhancing Electrochemiluminescence

Amine‐rich nitrogen‐doped carbon nanodots (NCNDs) have been successfully used as co‐reactant in electrochemiluminescence (ECL) processes. Primary or tertiary amino groups on NCNDs have been studied as co‐reactant sites for Ru(bpy)₃²⁺ ECL, showing their eligibility as powerful alternatives to tripropylamine (TPrA). We also report the synthesis and ECL behavior of a new covalently linked hybrid of NCNDs and Ru(bpy)₃²⁺. Notably, the NCNDs in the hybrid act both as carrier for ECL labels and as co‐reactant for ECL generation. As a result, the hybrid shows a higher ECL emission as compared to the combination of the individual components, suggesting the self‐enhancing ECL of the ruthenium complex due to an intramolecular electron transfer process.     

Ultrasensitive and Signal‐on Electrochemiluminescence Aptasensor Using the Multi‐tris(bipyridine)ruthenium(II)‐β‐cyclodextrin Complexes

An ultrasensitive and signal‐on electrochemiluminescence (ECL) aptasensor to detect target protein (thrombin or lysozyme) was developed using the host‐guest recognition between a metallocyclodextrin complex and single‐stranded DNA (ss‐DNA). The aptasensor uses both the photoactive properties of the metallocyclodextrins named multi‐tris(bipyridine)ruthenium(II)‐β‐cyclodextrin complexes and their specific recognition with ss‐DNA, which amplified the ECL signal without luminophore labeling. After investigating the ECL performance of different multi‐tris(bipyridine)ruthenium(II)‐β‐cyclodextrin (multi‐Ru‐β‐CD) complexes, tris‐tris(bipyridine)‐ruthenium(II)‐β‐cyclodextrin (tris(bpyRu)‐β‐CD) was selected as a suitable host molecule to construct an atasensor. First, double‐stranded DNA (ds‐DNA) formed by hybridization of the aptamer and its target DNA was attached to a glassy carbon electrode via coupling interaction, which showed low ECL intensity with 2‐(dibutylamino) ethanol (DBAE) as coreactant, because of the weak recognition between ds‐DNA and tris(bpyRu)‐β‐CD. Upon addition of the corresponding protein, the ECL intensity increased when target ss‐DNA was released because of the higher stability of the aptamer‐protein complex than the aptamer‐DNA one. A linear relationship was observed in the range of 0.01 pmol/L to 100 pmol/L between ECL intensity and the logarithm of thrombin concentrations with a limited detection of 8.5 fmol/L (S/N=3). Meanwhile, the measured concentration of lysozyme was from 0.05 pmol/L to 500 pmol/L and the detection limit was 33 fmol/L (S/N=3). The investigations of proteins in human serum samples were also performed to demonstrate the validity of detection in real clinical samples. The simplicity, high sensitivity and specificity of this aptasensor show great promise for practical applications in protein monitoring and disease diagnosis.     

Electrochemiluminescence of Tris(2,2′‐bipyridine)ruthenium with Various Co‐reactants under Ultrasound Irradiation

Electrochemiluminescence (ECL) of tris(2,2′‐bipyridine)ruthenium, Ru(bpy)₃²⁺ in the presence of various co‐reactants, such as tripropylamine (TPA), oxalate ion (C₂O₄^2?), ascorbic acid (H₂A) and dehydroascorbic acid (DHA), were investigated under ultrasound irradiation. In sono‐ECL experiments, an indium‐thin‐oxide (ITO) was used as working electrode, and a titanium tipped sonic horn probe (diameter 2 mm) which operated at a frequency of 20 kHz was set in the front of the ITO electrode. Under the ultrasound irradiation, ECL signals were found to be significantly enhanced when TPA and C₂O₄^2? were used as co‐reactants, only slightly enhanced in Ru(bpy)₃²⁺/DHA system, but total quenched in Ru(bpy)₃²⁺/H₂A system. The difference of Ru(bpy)₃²⁺ ECL behaviors for various co‐reactant could to be due to the different kinetics of catalytic reactions associated in ECL schemes. ECL quenching effect observed in Ru(bpy)₃²⁺/H₂A system was suggested to be due to electron transfer (ET) route between the excited state *Ru(bpy)₃²⁺ and ascorbate anion HA^? diffused from the bulk solution, where the diffusional HA^? species served as electron donor. The effect becomes more pronounced upon sonication because the effective collision frequency between *Ru(bpy)₃²⁺ and HA^? would be significantly increased by the enhanced mass transport effect of ultrasound.     

Syntheses of 3‐arm and 4‐arm star‐branched polystyrene Ru(II) complexes by the click‐to‐chelate approach

Metal template synthesis is a useful methodology to make sophisticated macromolecular architectures because of the variety of metal ion coordination. To use metal template methodology, chelating functionalities should be introduced to macromolecules before complexation. In this article, we demonstrate the click‐to‐chelate approach to install chelating functionality to polystyrene (PS) and complexation with Ru(II) ions to form 3‐arm and 4‐arm star‐branched PS Ru(II) complexes. Azide‐terminated PS (PS‐N₃) was readily prepared by atom transfer radical polymerization using 1‐bromoethylbenzene as an initiator followed by substitution of bromine by an azide group. The Cu(I)‐catalyzed 1,3‐dipolar cycloaddition of PS‐N₃ with 2‐ethynylpyridine or 2,6‐diethynylpyridine affords 2‐(1H‐1,2,3‐triazol‐4‐yl)pyridine (PS‐tapy) or 2,6‐bis(1H‐1,2,3‐triazol‐4‐yl)pyridine (PS‐bitapy) ligands bearing one or two PS chains at the first‐position of the triazole rings. Ru(II) complexes of PS‐tapy and PS‐bitapy were prepared by conventional procedure. The number‐averaged molecular weights (M_ns) of these complexes were determined to be 6740 and 10,400, respectively, by size exclusion chromatography using PS standards. These M_n values indicated the formation of 3‐arm and 4‐arm star‐branched PS Ru(II) complexes [Ru(PS‐tapy)₃](PF₆)₂ and [Ru(PS‐bitapy)₂](PF₆)₂ on the basis of the M_n values of PS‐tapy (2090) and PS‐bitapy (4970). The structures of these complexes were also confirmed by UV–vis spectroscopy and X‐ray crystallography of the Ru(II) complexes [Ru(Bn‐tapy)₃](PF₆)₂ and [Ru(Bn‐bitapy)₂](PF₆)₂, which bear a benzyl group instead of a PS chain. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Highly Sensitive Electrochemiluminescence Detection of Mercury(II) Ions Based on DNA‐Linked Luminol‐Au NPs Superstructure

A novel highly sensitive electrochemiluminescence (ECL) detection protocol for mercury(II) ions was developed. Based on the strong and stable thymine? thymine mismatches complexes coordination chemistry, mercury(II) ions can specifically bind to a designed DNA strand, leading to the release of the complimentary DNA strand. The released DNA strand was then captured by magnetic beads modified with specific DNA, and then through the formation of DNA‐linked luminol‐Au nanoparticles (NPs) superstructure, a specific ECL system for mercury(II) ions was developed. Using 3‐aminopropyl‐triethoxysilane as an effective enhancer, the ECL system can detect Hg²⁺ ion within a linear range from 2.0×10^?10 mol L^?1 to 2.0×10^?8 M, with a detection limit as low as 1.05×10^?10 M (3σ). Moreover, this ECL system is highly specific for Hg²⁺, without interference from other commonly coexisted metal ions, and it can be used for the analysis of real samples.     

A Novel Electrogenerated Chemiluminescence (ECL) Sensor Based on Ru(bpy)32+‐Doped Titania Nanoparticles Dispersed in Nafion on Glassy Carbon Electrode

A novel electrogenerated chemiluminescence (ECL) sensor based on Ru(bpy)₃²⁺‐doped titania (RuDT) nanoparticles dispersed in a perfluorosulfonated ionomer (Nafion) on a glassy carbon electrode (GCE) was developed in this paper. The electroactive component‐Ru(bpy)₃²⁺ was entrapped within the titania nanoparticles by the inverse microemulsion polymerization process that produced spherical sensors in the size region of 38±3 nm. The RuDT nanoparticles were characterized by electrochemical, transmission electron and scanning microscopy technology. The Ru(bpy)₃²⁺ encapsulation interior of the titania nanoparticles maintains its ECL efficiency and also reduces Ru(bpy)₃²⁺ leaching from the titania matrix when immersed in water due to the electrostatic interaction. This is the first attempt to prepare the RuDT nanoparticles and extend the application of electroactive component‐doped nanoparticles into the field of ECL. Since a large amount of Ru(bpy)₃²⁺ was immobilized three‐dimensionally on the electrode, the Ru(bpy)₃²⁺ ECL signal could be enhanced greatly, which finally resulted in the increased sensitivity. The ECL analytical performance of this ECL sensor for tripropylamine (TPA) was investigated in detail. This sensor shows a detection limit of 1 nmol/L for TPA. Furthermore, the present ECL sensor displays outstanding long‐term stability.     

Effect of Ionic Strength on the Electrochemiluminescence Generation by Tris(2,2'-bipyridyl)ruthenium(II)/Tri-n-propylamine

Electrochemiluminescence(ECL) is a powerful transduction technique used in biosensing and in vitro diagnosis, while the mechanism of ECL generation is complicated and affected by various factors. Herein the effect of ionic strength on ECL generation by the classical tris(2,2'-bipyridyl)ruthenium(II)[Ru(bpy)₃²⁺]/tri-n-propylamine(TPrA) system was investigated. It is clear that the ECL intensity decreases significantly with the increase of ionic strength, most likely arising from the reduced deprotonation rate of TPrA^+·. We further combined microtube electrode(MTE) with ECL microscopy to unravel the evolution of ECL layer with the variation of ionic strength. At a low concentration of Ru(bpy)₃²⁺, the thickness of ECL layer(TEL) nearly kept unchanged with the ionic strength, indicating the surface-confined ECL generation is dominated by the oxidative-reduction route. While at a high concentration of Ru(bpy)₃²⁺, ECL generation is dominated by the catalytic route and TEL increases remarkably with the increase of ionic strength, because of the extended diffusion length of Ru(bpy)₃³⁺ at a reduced concentration of TPrA^·.     

Enhanced Electrogenerated Chemiluminescence of Tris(2,2′‐bipyridyl) Ruthenium(II)/tripropylamine in the Presence of Pyridine and Its Analogues

In the present work, we conducted an investigation on the electrochemical and ECL behavior of Ru(bpy) /TPrA system in the presence of pyridine and its analogues on platinum and gold electrode. Results showed that pyridine and its analogues enhanced Ru(bpy) /TPrA ECL signal and exhibited different enhancement effects on different electrodes. On platinum electrode, the maximum enhancement factor of about 5 was obtained. On gold electrode, a low‐oxidation‐potential (LOP) ECL signal occurred and increased.     

Determination of Hg2+ in Tap Water Based on the Electrochemiluminescence of Ru(phen)32+ and Thymine at Bare and Graphene Oxide‐Modified Glassy Carbon Electrodes

The electrochemiluminescence (ECL) of the Ru(phen)₃²⁺/thymine (T) system at bare and graphene oxide (GO)‐modified glassy carbon (GC) electrodes was utilized to determine Hg²⁺ in tap water. The ECL intensity of Ru(phen)₃²⁺ was considerably enhanced by the addition of thymine because of the occurrence of ECL reaction between them. Subsequently, the ECL intensity of Ru(phen)₃²⁺/T system rapidly decreased with the addition of Hg²⁺ because of the formation of a T‐Hg²⁺‐T complex. A linear response (R²=0.9914) was obtained over a Hg²⁺ concentration range of 1.0×10^?9 mol/L to 1.0×10^?5 mol/L with a detection limit of 3.4×10^?10 mol/L at a bare GC electrode in 0.1 mol/L phosphate buffer (pH=8.0). The detection limit can be further reduced to 4.2×10^?12 mol/L after modification of the GC electrode by GO. To verify its applicability, the proposed method was utilized to determine Hg²⁺ in tap water and simulated wastewater. The method exhibited good reproducibility and stability and thus reveals the possibility of developing a novel ECL detection method for Hg²⁺.     

A Sandwich‐type Electrochemiluminescence Aptasensor for Thrombin Based on Functional Co‐polymer Electrode Using Ru(bpy)32+ Doped Nanocomposites as Signal‐amplifying Tags

Herein, a signal‐on sandwich‐type electrochemiluminescence (ECL) aptasensor for the detection of thrombin (TB) was proposed. The graphene (GR) doped thionine (TH) was electropolymerized synchronously on the bare glassy carbon electrode (GCE) to form co‐polymer (PTG) electrode. The gold nanoparticles (AuNPs) were decorated on the surface of the PTG by in‐situ electrodeposition, and the functional co‐polymer (PTG‐AuNPs) electrode was utilized as sensing interface. Then, TB binding aptamer I (TBA I) as capture probes were modified on the PTG‐AuNPs electrode to capture TB, and Ru(bpy)₃²⁺/silver nanoparticles doped silica core‐shell nanocomposites‐labeled TB binding aptamer II (RuAg/SiO₂NPs@TBA II) were used as signal probes to further bind TB, resulting in a sandwich structure. With the assistant of silica shell and AgNPs, the enrichment and luminous efficiency of Ru(bpy)₃²⁺ were significantly improved. Under the synergy of PTG‐AuNPs and RuAg/SiO₂NPs, the ECL signal was dramatically increased. The proposed ECL aptasensor displayed a wide linear range from 2 fM to 2 pM with the detection limit of 1 fM, which is comparable or better than that in reported ECL aptasensors for TB using Ru(bpy)₃²⁺ and its derivatives as the luminescent substance. The excellent sensitivity makes the proposed aptasensor a promising potential in pharmaceutical and clinical analysis.     

Highly Sensitive and Selective Detection of Pb(II) by NH2−SiO2/Ru(bpy)32+−UiO66 based Solid‐state ECL Sensor

In this study, a novel electrochemiluminescence (ECL) sensor for highly sensitive and selective detection of Pb(II) was developed based on Ru(bpy)₃²⁺ encapsulated UiO66 metal‐organic‐framework (Ru(bpy)₃²⁺?UiO66 MOF) and ?NH₂ group functionalized silica (NH₂?SiO₂). The NH₂?SiO₂ with large surface area provided an excellent platform for the ECL sensor. As numerous exposed carboxyl groups were present on UiO66 backbone, the Ru(bpy)₃²⁺?UiO66 could be steadily immobilized to NH₂?SiO₂ by forming amide bonds. Meanwhile, the introduced UiO66 MOF which used for the encapsulation of Ru(bpy)₃²⁺, significantly enhanced the ECL efficiency of the proposed sensor, as it possessed a large specific surface area and porosity for the loading of Ru(bpy)₃²⁺. Moreover, a high quenching effect on ECL intensity was obtained in the presence of Pb(II) in the electrolyte. Under the optimal conditions, the quenched ECL intensity showed a good linear relationship within Pb(II) concentration in the range from 1.0×10^?6 to 1.0×10² μM, with a detection limit of 1.0×10^?7 μM (S/N=3). The proposed sensor for Pb(II) detection was simple in operation, rapid in testing, stable in signal, and showed a good anti‐interference ability to some other metal ions. Besides, its application for detecting Pb(II) in a real sample was also investigated here. This work provides a potential platform for metal ions detection in environmental monitoring field.     

Synthesis and Characterization of Heteroleptic Ru(II) Complexes Based on 4,4′‐Bis((E)‐styryl)‐2,2′‐bipyridine as Ancillary Ligand and Application for Dye‐Sensitized Solar Cells

Heteroleptic Ru(II) complexes were designed based on 4,4′‐bis((E)‐styryl)‐2,2′‐bipyridine (bsbpy) as an ancillary ligand for dye‐sensitized solar cells (DSSCs), and those Ru(II) sensitizers, [Ru(L)(bsbpy)(NCS)₂][TBA] (TBA; tetrabutylammonium), were synthesized according to a typical one‐pot reaction of [RuCl₂(p‐cymene)]₂ with the corresponding anchoring ligands (where L = 4,4′‐dicarboxy‐2,2′‐bipyridine (dcbpy), 4,4′‐bis((E)‐carboxyvinyl)‐2,2′‐bipyridine (dcvbpy), 4,7‐dicarboxy‐1,10‐phenanthroline (dcphen), or 4,7‐bis((E)‐carboxyvinyl)‐1,10‐phenanthroline (dcvphen)). The new Ru(II) dyes, [Ru(L)(bsbpy)(NCS)₂][TBA] that incorporated vinyl spacer(s) into ancillary and/or anchoring ligand displayed red‐shifted bands over the overall UV/VIS region relative to the absorption spectra of N719 . A combination of bsbpy ancillary and dcphen anchoring ligand showed the best result for the overall power conversion efficiency (η); i.e., a DSSC fabricated with [Ru(dcphen)(bsbpy)(NCS)₂][TBA] exhibited a power conversion efficiency (η) of 2.98% (compare to N719 , 4.82%).     

Electrogenerated Chemiluminescence Ethanol Biosensor Based on Carbon Nanotube‐Titania‐Nafion Composite Film

Mesoporous titania‐Nafion composite doped with carbon nanotube (CNT) has been used for the immobilization of tris(2,2′‐bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) and alcohol dehydrogenase on an electrode surface to yield a highly sensitive and stable electrogenerated chemiluminescence (ECL) ethanol biosensor. The presence of CNT in the composite film increases not only the sensitivity of the ECL biosensor but also the long‐term stability of the biosensor. The present biosensor responds linearly to ethanol in the wide concentration ranges from 1.0×10^?5 M to 1.0×10^?1 M with a detection limit of 5.0×10^?6 M (S/N=3). The present ECL ethanol biosensor exhibited higher ECL response compared to that obtained with the ECL biosensor based on the corresponding composite without CNT. The present CNT‐based ECL biosensor showed good long‐term stability with 75% of its initial activity retained after 2 weeks of storage in 50 mM phosphate buffer at pH 7.0.     

Electrochemiluminescence Based on Solid State Tri(4,7‐diphenyl‐1,10‐phenanthroline) Ruthenium(II) Ditetrakis(4‐chlorophenyl) Borate Immobilized on Carbon Fibers

A simple method for immobilization of tri(4,7‐diphenyl‐1,10‐phenanthroline) ruthenium(II) ditetrakis(4‐chlorophenyl) borate ([Ru(dpp)₃][(4‐Clph)₄B]₂) on carbon fiber electrodes was developed. Excellent electrochemical activity and electrochemiluminescence (ECL) signal of the coated carbon fiber electrodes were observed using oxalate as the co‐reactant. In addition, the effects of pH, scan rate, nitrogen and oxygen on ECL intensity were also studied. To demonstrate the reliability, the coated carbon fiber electrodes were used as ECL detectors and very low concentration of phenol was detectable (5.0×10^?8 M).     

Ru(II)‐based antineoplastic: A “wingtip” N‐heterocyclic carbene facilitates access to a new class of organometallics that are cytotoxic to common cancer cell lines

The syntheses, structures, and chemotherapeutic activities of Ag(I)‐, Au(I)‐, and Ru(II)‐complexes ligated to a novel N‐heterocyclic carbene ligand, 2‐(4‐nitrophenyl)imidazo[1,5‐a]pyridin‐2‐ylidene ( 1 ), are described. The corresponding complexes, [Ag( 1 )₂][PF₆], [Au( 1 )₂][PF₆] ( 3 ), and [Ru( 1 )(p‐cymene)Cl][PF₆] ( 4 ), were prepared using convenient transmetallation chemistry and characterized using a range of spectroscopic and analytical techniques. X‐ray crystallography revealed that complexes 2 and 3 adopted linear structures whereas 4 exhibited a prototypical “piano‐stool”‐like geometry; the structural assignments were further supported by DFT calculations. A series of in vitro studies revealed that while the aforementioned Ag(I), Au(I) and Ru(II) complexes exhibited significant cytotoxicities against the human colon adenocarcinoma (HCT 116), lung cancer (A549), and breast cancer (MCF7) cell lines, the Ru derivative was most prominent.     

Design of a Solid‐State Electrochemiluminescence Biosensor for Detection of PML/RARα Fusion Gene Using Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$‐AuNPs Aggregations on Gold Electrode

A solid‐state electrochemiluminescence (ECL) biosensor based on special ferrocene‐labeled molecular beacon (Fc‐MB) for highly sensitive detection of promyelocytic leukemia/retinoic acid receptor alpha (PML/RARα) fusion gene was developed successfully using Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$ /2‐(dibutylamino)ethanol (DBAE) as detecting pattern. Such a special sensor involves two main parts, an ECL substrate and an ECL intensity switch. The ECL substrate was made by modifying the complex of Ruthenium (II) tris‐(bipyridine) and Au nanoparticles (Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$ ‐AuNPs) onto the Au electrode (AuE) surface. The molecular beacon probe in which the ferrocene tag could effectively quench the ECL of the Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$ acted as ECL intensity switch. The molecular beacon probe was designed with special base sequence, which could hybridize with its complementary target DNA. In the absence of a target, the hairpin structure of the probe forced the ferrocene (Fc) into close proximity with the ECL substrate, thus reducing ECL intensity. Target binding allowed the Fc away from the ECL substrate and resulted in an obvious increment in ECL intensity due to the decreased Fc quenching effect. The effect of the amount of Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$ and the mixing procedure of Ru(bpy)${{{2+\hfill \atop 3\hfill}}}$ and AuNPs solution on the fabrication of ECL film had been investigated. As a result, the change of ECL intensity had a direct relationship with the logarithm of PML/RARα fusion gene concentration in the range of 0.05–500 pM with a detection limit of 7 fM, and the developed biosensor possessed good molecular recognizability in human serum. Thus, the approach holds promise for the early diagnostics and prognosis monitoring of APL and other diseases.     

Electrogenerated Chemiluminescence of Tris(2,2′‐bipyridyl)ruthenium(II) Immobilized in Humic Acid‐Silica‐Poly(vinyl alcohol) Composite Films

In this paper, we report the first attempt to use humic acid (HA) as modifiers to prepare the organic‐inorganic hybrid modified glassy carbon electrodes based on HA‐silica‐PVA (poly(vinyl alcohol)) sol‐gel composite. Electroactive species of tris(2,2′‐bipyridyl)ruthenium(II) (Ru(bpy) ) can easily incorporate into the HA‐silica‐PVA films to form Ru(bpy) modified electrodes. The amount of Ru(bpy) incorporated in the composite films strongly depends on the amount of HA in the hybrid sol. Electrochemical and electrogenerated chemiluminescence (ECL) of Ru(bpy) immobilized in HA‐silica composite films coated on a glassy carbon electrode have been studied with tripropylamine (TPA) as the coreactant. The analytical performance of this modified electrode was evaluated in a flow injection analysis (FIA) system with a homemade flow cell. The as‐prepared electrode showed good stability and high sensitivity. The detection limits (S/N=3) were 0.050 μmol L^?1 for TPA and 0.20 μmol L^?1 for oxalate, and the linear ranges were from 0.10 μmol L^?1 to 1.0 mmol L^?1 for TPA and from 1.0 μmol L^?1 to 1.0 mmol L^?1 for oxalate, respectively. The resulting electrodes were stable over two months.     

Tris(2,2′‐bipyridyl)ruthenium(II) Electrogenerated Chemiluminescence Sensor Based on Platinized Carbon Nanotube–Zirconia–Nafion Composite Films

Mesoporous films of platinized carbon nanotube–zirconia–Nafion composite have been used for the immobilization of tris(2,2′‐bipyridyl)ruthenium (II) (Ru(bpy)₃²⁺) on an electrode surface to yield a solid‐state electrogenerated chemiluminescence (ECL) sensor. The composite films of Pt–CNT–zirconia–Nafion exhibit much larger pore diameter (3.55 nm) than that of Nafion (2.82 nm) and thus leading to much larger ECL response for tripropylamine (TPA) because of the fast diffusion of the analyte within the films. Due to the conducting and electrocatalytic features of CNTs and Pt nanoparticles, their incorporation into the zirconia–Nafion composite films resulted in the decreased electron transfer resistance within the films. The present ECL sensor based on the Pt–CNT–zirconia–Nafion gave a linear response (R²=0.999) for TPA concentration from 3.0 nM to 1.0 mM with a remarkable detection limit (S/N=3) of 1.0 nM, which is much lower compared to those obtained with the ECL sensors based on other types of sol‐gel ceramic–Nafion composite films such as silica–Nafion and titania–Nafion.