Electrogenerated chemiluminescence induced by sequential hot electron and hole injection into aqueous electrolyte solution

Hole injection into aqueous electrolyte solution is proposed to occur when oxide-coated aluminum electrode is anodically pulse-polarized by a voltage pulse train containing sufficiently high-voltage anodic pulses. The effects of anodic pulses are studied by using an aromatic Tb(III) chelate as a probe known to produce intensive hot electron-induced electrochemiluminescence (HECL) with plain cathodic pulses and preoxidized electrodes. The presently studied system allows injection of hot electrons and holes successively into aqueous electrolyte solutions and can be utilized in detecting electrochemiluminescent labels in fully aqueous solutions, and actually, the system is suggested to be quite close to a pulse radiolysis system providing hydrated electrons and hydroxyl radicals as the primary radicals in aqueous solution without the problems and hazards of ionizing radiation. The analytical power of the present excitation waveforms are that they allow detection of electrochemiluminescent labels at very low detection limits in bioaffinity assays such as in immunoassays or DNA probe assays. The two important properties of the present waveforms are: (i) they provide in situ oxidation of the electrode surface resulting in the desired oxide film thickness and (ii) they can provide one-electron oxidants for the system by hole injection either via F- and F⁺-center band of the oxide or by direct hole injection to valence band of water at highly anodic pulse amplitudes.     

基于壳聚糖/Ru（bpy）2+3/SiO2纳米粒子电化学发光传感器用于尿酸的检测

利用反相微乳液法制备了壳聚糖-Ru(bpy)2+3-SiO2复合纳米粒子,采用Nafion/MCNT复合膜技术实现了对复合纳米粒子有效而稳定的固定,从而制备了电化学发光传感器,实现了对尿酸的检测。在0.1 mol/L PBS缓冲溶液(pH 7.4)中,当尿酸与修饰电极作用15 min时,电化学发光强度与尿酸浓度(1.0×10-10~1.0×10-5 mol/L)的负对数呈良好的线性关系,线性方程为IECL=-709.52-202.74lgC,相关系数R=0.9936,检出限为6.0×10-12 mol/L。传感器表现出良好的重现性与稳定性,对1.0×10-8 mol/L尿酸平行测定11次,发光强度的相对标准偏差为2.9%,测定尿酸实际样品的加标回收率在98.5%~103.5%之间。     

Ultrasensitive Eletrogenerated Chemiluminescence Immunoassay by Magnetic Nanobead Amplification

An ultrasensitive electrogenerated chemiluminescence (ECL) immunoassay was proposed by using magnetic nanobeads (MNBs) as the carrier of ECL labels for ECL emission amplification. Carcinoembryonic antigen (CEA) and MNBs were initially immobilized on a platform in 1 : 1 molar ratio via sandwich immunoreaction. Subsequently, the MNBs were released from the platform and labeled with Ru(bpy)₃²⁺ species. After the MNBs with Ru(bpy)₃²⁺ were immobilized on an Au electrode, ECL of the Ru(bpy)₃²⁺ was measured for CEA determination. A linear relation between the ECL intensity and CEA concentration was obtained in a range of 1×10^?14 to 3×10^?13 mol/L (2.0 to 60 pg/mL) with a limit of detection of 8.0×10^?15 mol/L (1.6 pg/mL).     

联吡啶钌电化学发光传感器测定海洛因

利用离子液体为粘合剂制作碳糊电极,采用高分子聚合法,合成包埋有Ru(bpy)2(dcbpy)2+的高分子聚合物,将钌聚合物掺杂于离子液体碳糊电极中,制作电化学发光传感器.结果表明,此传感器具有很好的电化学发光特性,与用石蜡油为粘合剂制作的电化学发光传感器相比,离子液体为粘合剂的电化学发光传感器检测三丙胺的检出限降低1个数量级.海洛因对电化学发光传感器的发光信号有很好的增强作用,基于此建立了高灵敏度检测海洛因的电化学发光分析法,海洛因浓度与电化学发光信号在2.0×10-9～2.0×10-5 mol/L范围内呈良好的线性关系,检出限为8×10-10 mol/L (S/N=3).将电化学发光传感器在5.0×10-9 mol/L海洛因溶液中采用线性循环电位连续扫描60圈,相对标准偏差小于2.2%.本方法用于血清中海洛因的检测,其回收率为94%～101%.     

Electrochemiluminescent behaviors of alkaloids and tris(2,2'-bipyridine) ruthenium in organically modified silicate film

Electrogenerated chemiluminescences (ECLs) of alkaloids, such as berberine, trigonelline, allantoin and betaine, were studied in an aqueous alkaline buffer solution (pH 9.5), based on tris(2,2′-bipyridine)ruthenium(II) [Ru(bpy)₃²⁺] immobilized in organically modified silicates (ORMOSILs) film on a glassy carbon electrode (GCE). The immobilized Ru(bpy)₃²⁺ showed good electrochemical and photochemical activities. In a flow system, the eluted alkaloids were oxidized on the modified GCE, and reacted with immobilized Ru(bpy)₃²⁺ at the potential of +1.50 V (versus Ag/AgCl). The luminescence with λ_max 610 nm was caused by a reaction of electrolytically formed Ru(bpy)₃³⁺ with an oxidized amine group to generate Ru(bpy)₃^2+*. The determination limit was 5 × 10⁻⁶ mol L⁻¹, 8 × 10⁻⁶ mol L⁻¹, 2.0 × 10⁻⁵ mol L⁻¹ and 5.0 × 10⁻⁵ mol L⁻¹ for berberine, trigonelline, allantoin and betaine at S/N 3, respectively. In addition, the factors affecting the determination of the four alkaloids were also studied.     

Characterization of the low-oxidation-potential electrogenerated chemiluminescence of tris(2,2′-bipyridine)ruthenium(II) with tri-n-propylamine as coreactant

The electrogenerated chemiluminescence (ECL) of the Ru(bpy)₃²⁺ (bpy, 2,2′-bipyridine)/tri-n-propylamine (TPrA) system can be produced at an oxidation-potential well before the oxidation of Ru(bpy)₃²⁺. Here, we describe the unique features of the low-oxidation-potential (LOP) ECL. The LOP ECL exhibited strong dependence on solution pH with the maximum emission at pH  7.7. Compared with the conventional ECL, the LOP ECL was much more significantly diminished at high pH (>10), probably due to the short lifetime of TPrA cation radical which is a crucial intermediate for the LOP emission. It was also found that the preceding deprotonation step played an important role in TPrA oxidation at neutral pH and would remarkably influence the emission intensity. As excess intermediate radicals were produced upon rapid TPrA oxidation, only 5 mM TPrA was needed to achieve the maximum LOP ECL intensity in detecting trace Ru(bpy)₃²⁺ (<1 μM) and the LOP ECL response to Ru(bpy)₃²⁺ concentration was linear. Compared with the conventional Ru(bpy)₃²⁺/TPrA ECL, the LOP ECL technique not only produces higher emission intensity at lower oxidation-potential, but also significantly reduces the amount of the coreactant.     

Enhanced electrochemiluminescence from Os(phen)2(dppene) (phen=1,10-phenanthroline and dppene=bis(diphenylphosphino)ethene) in the presence of Triton X-100 (polyethylene glycol tert-octylphenyl ether)

The effects of the non-ionic surfactant Triton X-100 (polyethylene glycol tert-octylphenyl ether) on the properties of Os(phen)₂(dppene)²⁺ (phen=1,10-phenanthroline and dppene=bis(diphenylphosphino)ethene) electrochemiluminescence (ECL) have been investigated. The anodic oxidation of Os(phen)₂(dppene)²⁺ produces ECL in the presence of tri-n-propylamine (TPrA) in aqueous surfactant solution. Increases in ECL efficiency (≥3-fold) and TPrA oxidation current (≥2.0-fold) have been observed in surfactant media with experiments supporting adsorption of surfactant on the electrode surface.     

Electrogenerated Chemiluminescence Determination of Dopamine and Epinephrine in the Presence of Ascorbic Acid at Carbon Nanotube/Nafion‐Ru(bpy)$\rm{ {_{3}^{2+}}}$ Composite Film Modified Glassy Carbon Electrode

Based on the inhibition effect of dopamine and epinephrine on Ru(bpy) ‐tripropylamine electrogenerated chemiluminescence system, the excellent properties of carbon nanotube, and the cation permselectivity of Nafion film, an electrogenerated chemiluminescence inhibition method for determination of dopamine and epinephrine in the presence of ascorbic acid at carbon nanotube/Nafion‐Ru(bpy) composite film modified glassy carbon electrode was described. The results showed that the proposed method was sensitive and selective for the determination of dopamine and epinephine. The linear calibration range was from 1.6×10^?9 M to 3.2×10^?5 M and 5×10^?8 M to 6×10^?5 M for dopamine and epinephrine, respectively. 200‐fold excess of ascorbic acid did not interfere with the determination of 1 μM dopamine and epinephrine.     

Highly Sensitive Electrogenerated Chemiluminescence Detecting Ranitidine Based On Chemically Modifying Microenvironment of the Chemiluminescence Reaction

Using a graphite electrode modified with vaseline and NiO, ranitidine showed a strongly ECL enhancing effect for the weak ECL signal of electrooxidation of luminol. Based on this finding, a more sensitive ECL method for ranitidine was firstly proposed. Under the optimum experimental conditions, the ranitidine hydrochloride concentration in the range of 3.0×10^?8–9.0×10^?6 mol/L was proportional to the enhancing ECL signal and offered a 9×10^?9 mol/L detection limit for ranitidine hydrochloride. At the same time, based on the investigation on this ECL reaction mechanism, a new concept, to improve the suitable ECL reaction micro‐environment with chemically modified electrode technique for the better analytical performances of ECL analysis was also firstly proposed.     

Hot electron-induced electrogenerated chemiluminescence of 1-aminonaphthalene-4-sulphonate at oxide-covered aluminium electrodes in aqueous solution

Electrogenerated chemiluminescence of 1-aminonaphthalene-4-sulphonate (ANS) provides a sensitive means for the detection of the ANS in aqueous solution when oxide-covered aluminium electrodes are used as tunnel emission electrodes and cathodic pulse polarisation is used for the excitation of the luminophore. During the pulse polarisation of insulating oxide film-coated aluminium cathodes, hot electrons are tunnel emitted from the aluminium to the aqueous electrolyte solution by direct field-assisted tunnelling (in the case of oxide films of thickness 2-6 nm) or by Fowler-Nordheim (FN) tunnelling in the cases of thicker oxide films. As a result of direct tunnel emission of these energetic electrons, the generation of hydrated electrons (e_aq⁻) becomes possible. These electrochemically generated, extremely strong reductants (dry hot or hydrated electrons) make the efficient excitation of various types of luminophores at thin insulating film-covered electrodes possible and provide a means for sensitive immunoassays and DNA-probing assays when these luminophores are used as label molecules.