3D nanostructured Ni(OH)2 microspheres as an efficient immobilization matrix of Ru(bpy)3 for high-performance electrochemiluminescence sensor

The electrochemistry and electrochemiluminescence (ECL) of novel three-dimensional nanostructured Ru(bpy)₃²⁺/Ni(OH)₂ microspheres were investigated for the first time. The negatively charged porous Ni(OH)₂ microspheres composed of Ni(OH)₂ nanowires were specifically designed to interact with Ru(bpy)₃²⁺. The large surface area and porous structure of Ni(OH)₂ microspheres enhance loading of Ru(bpy)₃²⁺ and mass transport of the model analyte, tripropylamine (TPA). Excellent ECL performance of the presented sensor was achieved including good stability and wide linear range from 7.7 × 10⁻¹⁰ to 3.8 × 10⁻³ M with the detection limit of 2.6 × 10⁻¹⁰ M to TPA.     

Solid-state electrochemiluminescence sensor based on the Nafion/poly(sodium 4-styrene sulfonate) composite film

An effective electrochemiluminescence (ECL) sensor based on Nafion/poly(sodium 4-styrene sulfonate) (PSS) composite film-modified ITO electrode was developed. The Nafion/PSS/Ru composite film was characterized by atomic force microscopy, UV-vis absorbance spectroscopy and electrochemical experiments. The Nafion/PSS composite film could effectively immobilize tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) via ion-exchange and electrostatic interaction. The ECL behavior of Ru(bpy)₃²⁺ immobilized in Nafion/PSS composite film was investigated using tripropylamine (TPA) as an analyte. The detection limit (S/N = 3) for TPA at the Nafion/PSS/Ru composite-modified electrode was estimated to be 3.0 nM, which is 3 orders of magnitude lower than that obtained at the Nafion/Ru modified electrode. The Nafion/PSS/Ru composite film-modified indium tin oxide (ITO) electrode also exhibited good ECL stability. In addition, this kind of immobilization approach was simple, effective, and timesaving.     

Multi-walled carbon nanotubes and Ru(bpy)3/nano-Au nano-sphere as efficient matrixes for a novel solid-state electrochemiluminescence sensor

An effective method for immobilization of Ru(bpy)₃²⁺ on glassy carbon electrode surface (GCE) is developed for the preparation of a novel electrochemiluminescence sensor. First of all, the positively charged Ru(bpy)₃²⁺ is modified on the surface of negatively charged gold nanoparticles (nano-Au) via the electrostatic interactions to obtain the Ru(bpy)₃²⁺/nano-Au nano-sphere (abbreviate as Ru-AuNPs). Subsequently, the large amount of Ru-AuNPs are immobilized on the multi-wall carbon nanotubes (MWCNTs)-Nafion homogeneous composite coated GCE by dual interaction: firstly, the Nafion, a kind of typical cation-exchange membrane, can absorb the Ru-AuNPs as the enrichment of cation Ru(bpy)₃²⁺ on the Ru-AuNPs surface; secondly, the employment of carboxylic MWCNTs in the Nafion film can also chemosorb the Ru(bpy)₃²⁺ cation on the Ru-AuNPs surface to increase the carrier content. At the same time, the experiment confirms that the enhancement of the ECL intensity on the sensor is attributed to following reasons. One hand, the employment of MWCNTs in the Nafion film enlarged the electro-active surface areas to benefit the contact between the signal probe on the composite film and coreactant used as reinforcing agent. On the other hand, the nano-materials of MWCNTs and nano-Au also improve the conductivity of the assembled film to increase the quantity of excited state of Ru(bpy)₃²⁺ in the unit time under the electrochemical condition and finally cause better properties in luminescence. In the experiment, the influence of the coreactant tripropylamine (TPA) on proposed ECL sensor is investigated. The logarithm of ECL intensity is proportional to the logarithm of TPA concentration on the range of 4 × 10⁻¹⁰ M to 2.8 × 10⁻⁶ M and 2.8 × 10⁻⁶ M to 0.71 × 10⁻³ M. After optimizing these conditions, the ECL sensor with TPA as coreactant is employed to detect a kind of alkaloid medicine, Matrine, for evaluating the practical application in the medicine analysis. The present sensor with TPA as coreactant shows the good response to the medicine concentration of the Matrine from 2.0 × 10⁻⁶ M to 6.0 × 10⁻³ M, which is used to detect the Matrine concentration in the Matrine injection.     

A novel amperometric sensor for the detection of difenidol hydrochloride based on the modification of Ru(bpy)3 on a glassy carbon electrode

An amperometric sensor for the detection of difenidol, a tertiary amine-containing analyte, was proposed. Ruthenium(II) tris(bipyridine)/multi-walled carbon nanotubes/Nafion composite film was suggested to modify the glassy carbon electrode. The modified electrode was shown to be an excellent amperometric sensor for the detection of difenidol hydrochloride. The linear range is from 1.0 × 10⁻⁶ to 3.3 × 10⁻⁵ M with a correlation coefficient of 0.998. The limit of detection was 5 × 10⁻⁷ M, which was obtained through experimental determination based on a signal-to-noise ratio of three. The sensor was employed to the determination of the active ingredients in the tablets containing difenidol hydrochloride.     

[Ru(bpy)3] nanocomposites containing heteropolyacids: Simple preparation and stable solid-state electrochemiluminescence detection application

In order to solidify the electrochemiluminescence (ECL) luminophor tris(2,2′-bipyridyl) ruthenium(II) ([Ru(bpy)₃]²⁺) onto the electrode surfaces robustly, the negative charged heteropolyacids (HPAs) moieties were utilized to attract and bond cations [Ru(bpy)₃]²⁺ via an adsorption method. The compositions and microstructures of the hybrid complexes were characterized by elemental analysis (EDS), spectroscopic techniques (UV-vis, FTIR) and field-emission scanning electron microscopy (FE-SEM). The electrochemical and ECL behaviors of the [Ru(bpy)₃]²⁺/[PW₁₂O₄₀]³⁻ hybrid complex contained in the solid film of the nanocomposites formed on the electrode surfaces were also studied. It was found that the corresponding solid membranes exhibited a diffusion-controlled voltammetric feature and excellent electrochemiluminescence behaviors. Hence potential prospects as new electrochemiluminescent materials for application in electroanalytical detection are envisioned.     

Can clay emit light? Ru(bpy)3-modified clay colloids and their application in the detection of glucose

In this paper, we describe the electrochemiluminescent (ECL) behavior of Ru(bpy)₃³⁺-incorporated clay colloids. Experimental results based on the electrochemical-quartz-crystal-microbalance (EQCM) techniques showed that Ru(bpy)₃³⁺ could be adsorbed by the clay colloids (montmorillonite K10, denoted K10). The resulting clay particles could emit light (λ_em 610 nm) when they were fabricated as thin films sandwiched by two conductive ITO electrodes with opposite biases. These Ru(bpy)₃³⁺-incorporated clay-modified electrodes could also emit light in aqueous oxalate solutions (pH 10) when potentials more positive than 0.9 V vs. SCE were applied. EDTA was an effective promoter for the Ru(bpy)_{3 (clay)}³⁺-oxalate ECL reaction. The resulting ECL showed a remarkable sensitivity to oxygen. A glucose optrode was thus fabricated based on the Ru(bpy)₃³⁺-incorporated K10 colloids and glucose oxidase (GOx). The ECL signals behaved as a function of [glucose], covering a range from 0.1 to 10 mM at pH 10. The detection limits reached a level of 0.1 mM at this pH.     

CdTe-Ru(bpy)32 体系阴极电致化学发光法测定邻苯二酚

根据邻苯二酚对CdTe量子点增敏的Ru(bpy)3₂ 阴极电致化学发光的强度有较强的抑制作用,建立了一种简单的测定邻苯二酚的电致化学发光(ECL)分析方法。实验依次探究了磷酸盐缓冲溶液的浓度、pH值、量子点的浓度、Ru(bpy)3₂ 的浓度、扫描速率以及电位等因素对该体系发光行为的影响。在最佳实验条件下,电致化学发光强度的对数与邻苯二酚浓度的对数在7.0×10_?8～4.0×10_?5 mol L_?1范围内呈现良好的线性关系,检出限为2.3×10_?8 mol L_?1(3σ)。对4.0×10_?6 mol L_?1的邻苯二酚标准溶液进行六次平行测定,其电致化学发光强度的相对标准偏差(RSD)为1.1 %。进一步,该方法可成功应用于模拟环境水样中邻苯二酚的含量测定,加标回收率介于95.0～105.7 %之间。     

十二烷基磺酸钠-盐酸维拉帕米-联吡啶钌体系电化学发光及其应用

在十二烷基磺酸钠(SDS)中,考察了盐酸维拉帕米-Ru(bpy)3(2+)体系在金电极上的电化学及其发光行为.结果表明:SDS对体系的电化学反应和电化学发光强度具有显著的增敏作用.据此,建立了一种高效、简便的测定盐酸维拉帕米的电化学发光新方法.在最佳实验条件下,盐酸维拉帕米浓度在1.0×10(-4)～1.0×10(-2...     

玻碳电极上Ru(bpy)32+的吸附及其电致化学发光的研究

通过电化学循环伏安法和电致化学发光方法, 研究了Ru(bpy)₃²⁺在玻碳电极上的吸附, 研究结果表明, Ru(bpy)₃²⁺的浓度和与玻碳材料接触的时间, 直接影响了Ru(bpy)₃²⁺在玻碳上的吸附. 还考察了吸附的 在玻碳电极上被氧化后脱附的情况.     

Electrochemiluminescence immunosensor for ultrasensitive detection of biomarker using Ru(bpy)3-encapsulated silica nanosphere labels

Here, we describe a new approach for electrochemiluminescence (ECL) assay with Ru(bpy)₃²⁺-encapsulated silica nanoparticle (SiO₂@Ru) as labels. A water-in-oil (W/O) microemulsion method was employed for one-pot synthesis of SiO₂@Ru nanoparticles. The as-synthesized SiO₂@Ru nanoparticles have a narrow size distribution, which allows reproducible loading of Ru(bpy)₃²⁺ inside the silica shell and of α-fetoprotein antibody (anti-AFP), a model antibody, on the silica surface with glutaraldehyde as linkage. The silica shell effectively prevents leakage of Ru(bpy)₃²⁺ into the aqueous solution due to strong electrostatic interaction between the positively charged Ru(bpy)₃²⁺ and the negatively charged surface of silica. The porous structure of silica shell allowed the ion to move easily through the pore to exchange energy/electrons with the entrapped Ru(bpy)₃²⁺. The as-synthesized SiO₂@Ru can be used as a label for ultrasensitive detection of biomarkers through a sandwiched immunoassay process. The calibration range of AFP concentration was 0.05-30 ng mL⁻¹ with linear relation from 0.05 to 20 ng mL⁻¹ and a detection limit of 0.035 ng mL⁻¹ at 3σ. The resulting immunosensors possess high sensitivity and good analytical performance.     

High electrochemiluminescence intensity of the Ru(bpy)3 2+/oxalate system on a platinum net electrode

A new method for enhancing the electrochemiluminescence (ECL) intensity of the Ru(bpy)₃ ²⁺/ oxalate system is presented. When a platinum net was used as a working electrode and a platinum foil as an auxiliary electrode, the ECL intensity of the system was enhanced greatly. In addition, a cathodic peak appeared at 0.18 V (vs. SCE) on a platinum net electrode, and ECL of the system was observed at 0.18 V.     

Determination of itopride hydrochloride by high-performance liquid chromatography with Ru(bpy)3 electrogenerated chemiluminescence detection

In this work, a stable electrogenerated chemiluminescence (ECL) detector was developed. The detector was prepared by packing cation-exchanged resin particles in a glass tube, followed by inserting Pt wires (working electrode) in this tube and sealing. The leakage of Ru(bpy)₃²⁺ can be compensated by adding a small amount of Ru(bpy)₃²⁺ into solution phase. Coupled with high-performance liquid chromatography separation, the detector has been used for determination of itopride hydrochloride in human serum. Under the optimal conditions, the ECL intensity has a linear relationship with the concentration of itopride hydrochloride in the range of 1.0 × 10⁻⁸ g mL⁻¹ to 1.0 × 10⁻⁶ g mL⁻¹ and the detection limit was 3 × 10⁻⁹ g mL⁻¹ (S/N = 3). The as-prepared ECL detector displayed good sensitivity and stability.     

Ru(bpy)_3 掺杂的核壳型 Ag@SiO_2 荧光纳米粒子的制备及表征

利用反相微乳液法制备了一种三联吡啶钌掺杂的核壳型Ag@SiO2纳米粒子。利用透射电子显微镜、荧光光谱和紫外-可见光谱等对其进行表征,并对其光稳定性和表面氨基进行了测定,结果表明该纳米粒子单分散性良好,呈规则球状、粒径为(60±5)nm,由于银的金属增强荧光效应,相对没有银核的Ru(bpy)3掺杂的SiO2纳米粒子,其荧光强度增强了2倍,光稳定性也有所提高。     

A fiber-optic evanescent wave sensor for dissolved oxygen detection based on novel hybrid fluorinated xerogels immobilized with [Ru(bpy)3]2+

We have prepared a novel fiber-optic evanescent wave sensor (FEWS) for dissolved oxygen (DO) detection. The sensor fabrication was based on coating a decladded portion of an optical fiber with a microporous coating, which was prepared from 3,3,3-trifluoropropyltrimethoxysilane and n-propyltrimethoxysilane. The fluorophores were immobilized in the porous coating and excited by the evanescent wave field produced on the core surface of the optical fiber. The sensitivity of the sensor was quantified by the ratio of the fluorescence intensities in pure deoxygenated (I ₀) and in pure oxygenated environments (I). Results show that the quenching response of DO is increased with the enhancement of the coating surface hydrophobicity using the presented hybrid fluorinated ORMOSILs. The calibration curve of I ₀/I to [O₂] is linear from 0 to 40 ppm and the detection limit is 0.05 ppm (3σ) with a short response time of 15 s for DO detection. Figure       

Electrogenerated chemiluminescence biosensor based on Ru(bpy)3(2+) and dehydrogenase immobilized in sol-gel/chitosan/poly(sodium 4-styrene sulfonate) composite material

A new electrogenerated chemiluminescence biosensor was fabricated by immobilizing ECL reagent Ru(bpy)₃²⁺ and alcohol dehydrogenase in sol-gel/chitosan/poly(sodium 4-styrene sulfonate) (PSS) organically modified composite material. The component PSS was used to immobilize ECL reagent Ru(bpy)₃²⁺ by ion-exchange, while the addition of chitosan was to prevent the cracking of conventional sol-gel-derived glasses and provide biocompatible microenvironment for alcohol dehydrogenase. Such biosensor combined enzymatic selectivity with the sensitivity of ECL detection for quantification of enzyme substrate and it was much simpler than previous double-layer design. The detection limit was 9.3 × 10⁻⁶ M for alcohol (S/N = 3) with a linear range from 2.79 × 10⁻⁵ to 5.78 × 10⁻² M. With ECL detection, the biosensor exhibited wide linear range, high sensitivity and good stability.     

Determination of sulfur contents of SO3, S2O3 and S based on the electrocatalytic interaction with homogeneous mediator tris(2,2'-bipyridyl)Ru(II)

A sensitive voltammetric method has been developed for the determination of total or single species of sulfur anions containing sulfide, sulfite and thiosulfate. The method is based on the catalytic effect of tris(2,2'-bipyridyl)Ruthenium(II) (Ru(bpy)₂^+ 2) as a homogeneous mediator on the oxidation of those anions at the surface of a glassy carbon electrode. A reversible redox couple of Ru(II)/Ru(III) were observed as a solute in aqueous solution. Cyclic voltammetry study showed that the catalytic current of the system depends on the concentration of the anions. Optimum pH values for voltammetric determination of sulfite, thiosulfate and sulfide has been found to be 5.6, 10.0 and 10.0, respectively. Under the optimized conditions the calibration curves have been obtained linear in the concentration ranges of 0.8–500.0, 0.4–1000.0 and 0.5–5000.0 µmol L^− 1 of SO₃²⁻, S₂O₃²⁻ and S²⁻, respectively. The detection limits have been calculated to be 0.40, 0.17 and 0.33 µmol L^− 1 for SO₃²⁻, S₂O₃²⁻ and S²⁻, respectively. The diffusion coefficients of sulfite and thiosulfate have been estimated using chronoamperometry. The chronoamperometric method also has been used to determine the catalytic rate constant for catalytic reaction of the Ru(bpy)₂^+ 2 with sulfite and thiosulfate. Finally the proposed method has been used for the determination of total sulfur contents in real samples of water and wastewater. Moreover the sulfite content in sugar and sulfur dioxide in air has been determined with satisfactory results.     

Nafion–RuO2–Ru(bpy)3 composite electrodes for efficient electrocatalytic water oxidation

Electrocatalytic water oxidation to evolve O₂ was studied on a Nafion–RuO₂–Ru(bpy)₃²⁺ composite electrode. The O₂ evolution current efficiency was largely improved for the multi-component electrode over the Nafion–RuO₂ and Nafion–Ru(bpy)₃²⁺ individuals. The redox mediation through the Ru(bpy)₃²⁺ was found to dominate over the RuO₂ catalytic effect in the water oxidation mechanism. The specific surface area of the RuO₂, which was prepared at different temperatures (300–700°C), used in fabricating the composite electrode also played an important role in the overall water oxidation mechanism. Both the reaction and electrode parameters were optimized to get effective electrocatalytic current values in this study.     

Determination of indole-3-acetic acid and indole-3-butyric acid in mung bean sprouts using high performance liquid chromatography with immobilized Ru(bpy)3-KMnO4 chemiluminescence detection

A novel method for determination of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) in an extract from mung bean sprouts using high performance liquid chromatography (HPLC) with chemiluminescence (CL) detection is described. The method is based on the CL reaction of auxin (indole-3-acetic acid and indole-3-butyric acid) with acidic potassium permanganate (KMnO₄) and tris(2,2′-bipyridyl)ruthenium(II), which was immobilized on the cationic ion-exchange resin. The chromatographic separation was performed on a Nucleosil RP-C18 column (i.d.: 250 mm × 4.6 mm, particle size: 5 μm, pore size: 100) with an isocratic mobile phase consisting of methanol-water-acetic acid (45:55:1, v/v/v). At a flow rate of 1.0 mL min⁻¹, the total run time was 20 min. Under the optimal conditions, the linear ranges were 5.0 × 10⁻⁸ to 5.0 × 10⁻⁶ g mL⁻¹ and 5.0 × 10⁻⁷ to 1.0 × 10⁻⁵ g mL⁻¹ for IAA and IBA, respectively. The detection limits were 2.0 × 10⁻⁸ g mL⁻¹ and 2.0 × 10⁻⁷ g mL⁻¹ for IAA and IBA, respectively. The relative standard deviation (RSD) of intra-day were 3.1% and 2.3% (n = 11) for 2 × 10⁻⁶ g mL⁻¹ IAA and 2 × 10⁻⁶ g mL⁻¹ IBA; The relative standard deviations of inter-day precision were 6.9% and 4.9% for 2 × 10⁻⁶ g mL⁻¹ IAA and 2 × 10⁻⁶ g mL⁻¹ IBA. The proposed method had been successfully applied to the determination of auxin in mung bean sprouts.     

Modulated potential electrogenerated chemiluminescence of luminol and Ru(bpy) 3 2+

Chemiluminescence emission intensity is modulated by modulating the potential of a working electrode which is used to generate a key species in the electrogenerated Chemiluminescence (ECL) reaction. The emission is monitored synchronously using a lock-in amplifier. The reactions used in the characterization are luminol with hydrogen peroxide and tris(2,2-bipyridyl)ruthenium (II) (or Ru(bpy) ₃ ²⁺ ) with oxalate. Modulation widths of ± 50 mV yield maximum signals for luminol when centered at 0.45 V (vs Ag/AgCl) and for Ru(bpy) ₃ ²⁺ when centered at 1.05 V. The resulting signal decreases with increasing modulation frequency and shows that luminol/H₂O₂ is a faster ECL system than Ru(bpy) ₃ ²⁺ /oxalate. Working curves for luminol and for oxalate have essentially the same linear range and slope with the modulated potential approach as with a DC electrode potential. This approach provides capability for differentiating the analytical signal from constant background emission or stray light.