Electrochemiluminescence Immunosensor Based on Functionalized Graphene/Fe3O4‐Au Magnetic Capture Probes for Ultrasensitive Detection of Tetrodotoxin

An ultrasensitive electrochemiluminescence (ECL) immunosensor for the detection of tetrodotoxin (TTX) is proposed, which are composed of the branched poly‐(ethylenimine) (BPEI) functionalized graphene (BGNs)/Fe₃O₄‐Au magnetic capture probes and luminol‐capped gold nanocomposites (luminol‐AuNPs) as the signal tag. Herein, a typical sandwich immunecomplex was constructed on the glassy carbon electrode. The BGNs/Fe₃O₄‐Au hybrids could efficiently conjugate primary antibody via the Au−S chemical bonds or Au−N chemical bonds and rapidly separate under external magnetic field. The introduction of BPEI to GO could enhance the luminol‐ECL intensity. Meanwhile, the multifunctional nanocomposites have been proved with good water‐solubility, excellent electron transfer, outstanding stability, etc. The luminescent luminol‐AuNPs, a high efficient electrochemiluminescence marker, can be assembled on the second antibody, which can produce the ECL signal to achieve the determination of TTX. This proposed ECL immunosensor with a linear range from 0.01–100 ng/mL can be applied in the detection of TTX in real samples with satisfactory results.     

Electrochemiluminescence biosensor for carcinoembryonic antigen detection based on Au-Ag/g-C3N4 nanocomposites

Herein, an electrochemiluminescence (ECL) aptasensor for carcinoembryonic antigen (CEA) detection was developed based on Au-Ag/g-C₃N₄ nanocomposites (NCs), which were synthesized by decorating graphitic carbon nitride (g-C₃N₄) nanosheets with alloy-structured Au-Ag bimetallic nanoparticles (NPs) via one-step in situ chemical reduction. As ECL sensing platform, Au-Ag/g-C₃N₄ NCs could significantly improve the ECL intensity of luminol due to the good conductivity of Au-Ag NPs, electrocatalytic activity for oxygen evolution reaction (OER) and the ability to adsorb luminol via π stacking interaction. In addition, it could load the thiol terminated aptamers of CEA via Au-S or Ag-S bonds. In the presence of CEA, the ECL response of the proposed biosensor decreased significantly due to the fact that the assembled protein layers hindered the electron transfer and the diffusion of ECL reactants toward the electrode surface. The proposed ECL sensor exhibited a good linear relationship with CEA in the range of 1.0–1.0 × 10^?6 ng/mL with a detection limit of 8.9 × 10^?7 ng/mL. The satisfactory results were obtained in the detection of CEA in human serum samples.     

A Sensitive Surface‐enhanced Raman Scattering Method for Determination of Melamine with Aptamer‐modified Nanosilver Probe

The small nanosilver was prepared by the sodium borohydride procedure. The aptamer was used to modify nanosilver to obtain a nanosilver‐aptamer (AgssDNA) SERS probe for the determination of melamine. In pH 6.6 phosphate buffer solution and in the presence of NaCl, the AgssDNA probe specifically combined with melamine to release nanosilver particles that were aggregated to nanosilver clusters, which exhibited SERS effect at 240 cm^?1. When melamine concentration increased, the nanosilver clusters increased, and the SERS intensity at 240 cm^?1 increased. The increased SERS intensity ΔI_{240 cm?1} is linear to melamine concentration in the range of 6.3–403.6 μg·L^?1, with a detection limit of 1.2 μg·L^?1. This assay was applied to determination of melamine in milk, with satisfactory results.     

用于低浓度三聚氰胺选择性检测的铝/银纳米传感器的组装及其SERS性能

通过置换法在铝板上快速制备了一种即插即用型的Al/Ag纳米表面增强拉曼光谱(SERS)活性基底。结果表明该SERS基底较好地解决了银纳米颗粒在支撑物质上的吸附问题,能够快速实现对三聚氰胺的检测,而且具有操作简单、成本低、无损伤检测等优点,最低检测浓度能达到10^-7 mol·L^-1,满足国家食品安全要求的最低标准。另外,Al/Ag活性基底对三聚氰胺检测具有较高的拉曼测试重现性,连续测定15 h的过程中拉曼强度波动不大;且该Al/Ag活性基底能够在三乙醇胺、N,N-二甲基甲酰胺和1,2-丙二胺等胺类物质中实现对三聚氰胺的选择性检测。     

A Highly Sensitive Electrochemiluminescence Choline Biosensor Based on Poly(aniline‐luminol‐hemin) Nanocomposites

Poly(aniline‐luminol‐hemin) nanocomposites are prepared on an electrode surface through electropolymerization, and a highly sensitive electrochemiluminescence (ECL) biosensor for choline is developed based on the poly(aniline‐luminol‐hemin) nanocomposites and an enzyme catalyzed reaction of choline oxidase (CHOD). The obtained nanocomposites are characterized by scanning electron microscopy (SEM), atomic absorption spectrometry (AAS) and ECL. The results indicate that hemin can be incorporated into the poly(aniline‐luminol) nanocomposites using the facile electropolymerization method, and the poly(aniline‐luminol‐hemin) nanocomposites are rod shaped porous nanostructure. Moreover, the poly(aniline‐luminol‐hemin) nanocomposites exhibit higher ECL intensity than poly(aniline‐luminol) nanocomposites in alkaline media due to the catalytic effect of hemin on the ECL of the polymerized luminol and the electron transfer ability of hemin in the nanocomposites. CHOD is immobilized on the surface of the poly(aniline‐luminol‐hemin) nanocomposites modified electrode with glutaraldehyde, and the ECL biosensor based on poly(aniline‐luminol‐hemin)/CHOD exhibits a wider linear range for the choline detection. The enhanced ECL signals are linear with the logarithm of concentration of choline over the range of 1.0×10^?11～1.0×10^?7 mol L^?1 with a low detection limit of 1.2×10^?12 mol L^?1. Moreover, the proposed biosensor is successfully applied to the detection of choline in milk.     

Quantitative Monitoring of Rutin in Human Urine by Flow Injection‐Chemiluminescence Analysis

In this paper, a rapid and sensitive flow injection‐chemiluminescence (FI‐CL ) method is proposed for the quantitative determination of rutin based on the inhibitory effect of rutin on the chemiluminescence intensity from the luminol–chymotrypsin (CT ) system. The decrease of CL intensity was found to be proportional to the logarithm of rutin concentration in the range 0.1–30.0 ng/mL . A method for the quantification of rutin is proposed, with the limit of detection (LOD ) of 0.03 ng/mL (3σ). A complete analytical process including sampling and washing for rutin determination, which was conducted at a flow rate of 2.0 mL /min, could be performed completely within 30 s, yielding a sample efficiency of 120 h⁻¹. The proposed procedure was successfully applied for the determination of rutin in human urine after oral intake, with recoveries varying from 93.9 to 108.1% and relative standard derivation <4.0% (n = 5). Results showed that urine reached the maximum concentration at ~2.5 h, and the total excretion ratios were (83.5 ± 0.6) and (86.8 ± 0.7)%, respectively, for two volunteers in 8 h. The pharmacokinetic parameters, including the half‐life (1.05 ± 0.02 h), absorption rate constant (1.18 ± 0.01 h⁻¹), and elimination rate constant (0.70 ± 0.01 h⁻¹), were obtained. The possible CL mechanism of the luminol–CT –rutin reaction is discussed by FI‐CL , fluorescence, and molecular docking methods.     

三聚氰胺单试剂荧光偏振免疫分析法

用三聚氰胺半抗原(MEL)与异硫氰酸荧光素乙二胺(EDF)反应合成了荧光示踪物MEL-EDF, 示踪物与三聚氰胺抗体反应得到稳定的单试剂免疫复合物, 考察了其结合动力学和置换动力学过程, 建立了一种三聚氰胺单试剂荧光偏振免疫分析方法(SR-FPIA). 该方法的检出限(LOD)为3.2 ng/mL, 半抑制浓度(IC₅₀)为157.1 ng/mL, 检测范围(IC₂₀~IC₈₀)为12.2~1012.4 ng/mL, 能够满足国家标准和国际食品法典委员会(CAC)对于食品中三聚氰胺最高残留限量的检测要求. 整个检测过程在15 min内完成, 并且单试剂免疫复合物在4℃下至少可稳定保存30 d以上. 本研究对开发三聚氰胺新型免疫检测方法具有重要意义.     

Single-Atom Iron Boosts Electrochemiluminescence

The traditional luminol–H₂O₂ electrochemiluminescence (ECL) sensing platform suffers from self-decomposition of H₂O₂ at room temperature, hampering its application for quantitative analysis. In this work, for the first time we employ iron single-atom catalysts (Fe-N-C SACs) as an advanced co-reactant accelerator to directly reduce the dissolved oxygen (O₂) to reactive oxygen species (ROS). Owing to the unique electronic structure and catalytic activity of Fe-N-C SACs, large amounts of ROS are efficiently produced, which then react with the luminol anion radical and significantly amplify the luminol ECL emission. Under the optimum conditions, a Fe-N-C SACs–luminol ECL sensor for antioxidant capacity measurement was developed with a good linear range from 0.8 μm to 1.0 mm of Trolox.     

Determination of melamine in dairy products by an electrochemiluminescent method combined with solid-phase extraction

An electrochemiluminescence (ECL) enhancement method combined with solid-phase extraction has been developed for the determination of melamine in dairy products. It was found that melamine in a strong base solution is able to enhance the ECL of Ru(bpy)₃²⁺ at glass carbon electrode. The optimum experimental conditions for the determination of trace melamine by ECL, such as scan mode and scan rate of the applied potential, the type of buffer solutions and their pH conditions, were investigated. Under optimized conditions, the enhanced ECL intensity was linearly proportional to the logarithm of melamine concentration in the range of 0.01-1.0 ppb, and the detection limit was 0.003 ppb. The method has been successfully demonstrated to determine melamine in dairy products including liquid milk, yogurt and milk powder samples. The relative standard deviations ranging from 5.3% to 11.2% and the recoveries from 95.2% to 102.4% were acquired by this method. A possible mechanism for the ECL enhancement effect was also proposed.     

Single‐Atom Iron Boosts Electrochemiluminescence

The traditional luminol–H₂O₂ electrochemiluminescence (ECL) sensing platform suffers from self‐decomposition of H₂O₂ at room temperature, hampering its application for quantitative analysis. In this work, for the first time we employ iron single‐atom catalysts (Fe‐N‐C SACs) as an advanced co‐reactant accelerator to directly reduce the dissolved oxygen (O₂) to reactive oxygen species (ROS). Owing to the unique electronic structure and catalytic activity of Fe‐N‐C SACs, large amounts of ROS are efficiently produced, which then react with the luminol anion radical and significantly amplify the luminol ECL emission. Under the optimum conditions, a Fe‐N‐C SACs–luminol ECL sensor for antioxidant capacity measurement was developed with a good linear range from 0.8 μm to 1.0 mm of Trolox.     

电化学发光淬灭法测定SOD

在硼酸缓冲溶液（pH6．7）中性介质中,O2和H2O2均对鲁米诺的电化学发光（ECL）有敏化作用,而超氧化物歧化酶（SOD）对此敏化的电化学发光具有淬灭作用,SOD的浓度与两种发光体系的ECL光强成线性关系,可用于SOD的测定,为SOD的测定提供了一种灵敏、可靠的测定方法。     

A Novel Electrogenerated Chemiluminescence Reaction Scheme Using Core-Shell LuminoI-Based SiO2 Nanoparticles as a Regulator and Its Analytical Application

A novel core-shell luminol-based SiO2 nanoparticle While these nanoparticles were used as electrogenerated was synthesized by two step micro-emulsion method. chemiluminescence （ECL） reagent, the electrochemical （EC） reaction as well as the subsequent chemiluminescence （CL） reaction not only could be separated spatially, but also presented high efficiency for analytical purpose. In this case, the core-shell luminol-based SiO2 nanoparticles offered more potential to avoid the contradiction between the EC and the CL reaction conditions. A new ECL method based on the nanoparticle was developed, and isoniazid was selected as a model analyte to illustrate the characteristics of this new ECL method. Under the selected conditions, the proposed ECL response to isoniazid concentration was linear in the range of 1.0 ×10^-10 to 1.0 × 10^-6 g/mL with 2 × 10^-11g/mL detection limit.     

Electrochemiluminescence Based Enzymatic Urea Sensor Using Nanohybrid of Isoluminol‐gold Nanoparticle‐graphene Oxide Nanoribbons

This study evaluates on the possibility of using gold nanoparticles functionalized with the luminol derivative N‐(aminobutyl)‐N‐(ethylisoluminol) (ABEI) and hybridized with graphene oxide nanoribbons on a carbon based screen‐printed electrode (ABEI‐AuNP‐GONR/SPE) as an enzymatic electrochemiluminescence (ECL) urea sensor. The electrocatalytic activity and ECL intensity of ABEI‐AuNP‐GONR/SPE were found to increase proportionally with the concentration of urea in the analyte sample, owing to the rise in pH value. These phenomena are attributed to increased formation of luminol monoanion precursors for further electrochemical oxidation, which in turn produce either luminol radicals or excited 3‐amino‐phthalate molecules. The luminescence is most likely caused by the interaction of luminol radicals with superoxide radicals formed from dissolved oxygen. The sensitivity of our sensor was determined to be 170.58 mM⁻¹ and 16.23 mM⁻¹ for urea concentrations from 2 to 5.82 mM and from 5.82 to 30 mM, respectively, covering the normal urea level in human blood.     

Electrochemiluminescence of SDBS‐Ru(bpy)32+‐CPM System and Its Application

When the concentration of dodecyl benzene sulfonic acid sodium salt (SDBS) is 0.7 mmol·L^?1, the electrochemical and electrochemiluminescence (ECL) intensity of Ru(bpy)₃²⁺‐chlorpheniramine maleate (CPM) system at the Au electrode were studied. The results showed that compared with the absence of SDBS, enhancement of the ECL intensity was 14‐fold at Au electrode. Base on this, an ECL method was established for efficient and simple determination of CPM at Au electrode. Under the optimum experimental condition, the enhanced ECL intensities had good linear relationship with the concentration of CPM in the range of 1.0×10^?4–1.0×10^?7 mol·L^?1, and a linear regression equation was obtained as follows: I (counts)=48.805×10⁶c+394.03 (r=0.9975), the detection limit for CPM was 1.4×10^?8 mol·L^?1. The RSD for 5 times determinations of 1.0×10^?5 mol·L^?1 CPM was 3.2%. The results of recovery test were between 96.3%–102.5%, and the RSD of recovery test (n=5) was 2.7%. In addition, eleven kinds of tertiary amines‐Ru(bpy)₃²⁺ systems were investigated in the absence and presence of SDBS. The results showed that the enhancement of SDBS on ECL intensity of tertiary amines‐Ru(bpy)₃²⁺ systems was universal.     

Clopyralid detection by using a molecularly imprinted electrochemical luminescence sensor based on the “gate-controlled” effect

A new strategy for trace analysis was proposed by preparing a molecularly imprinted polymer (MIP) sensor. The template molecules of clopyralid were determined based on “gate-controlled” electrochemiluminescence (ECL) measurement. A dense polymer film was electropolymerized on an electrode surface to fabricate the MIP–ECL sensor. The process of template elution and rebinding acted as a gate to control the flux of probes, which pass through the cavities and react on the electrode surface. ECL measurement was conducted in the luminol–H₂O₂ system. A linear relationship between ECL intensity and clopyralid concentrations in the range of 1?×?10^?9 mol/L to 8?×?10^?7 mol/L exists, and the detection limit was 3.7?×?10^?10 mol/L. The prepared sensor was used to detect clopyralid in vegetables. Recoveries of 97.9 % to 102.9 % were obtained. The sensor showed highly selective recognition, high sensitivity, good stability, and reproducibility for clopyralid detection.     

A sensitive DNA biosensor based on the distance dependent quenching of Silica@Ru(bpy)32+-chitosan-GO electrochemiluminescence by Ferrocene@Gold nanoparticles

A sensitive electrochemiluminescence (ECL) biosensor for the specific DNA sequence of hepatitis C virus (HCV) was developed based on the efficient quenching effect of the ferrocene cluster functionalized gold nanoparticles (Fc@AuNPs) on the ECL of electrodeposited silica@Ru(bpy)₃²⁺-chitosan-graphene oxide nanocomposite (SiO₂@Ru−CS−GO). Graphene oxide (GO) can accelerate electron transfer rate, thus improving the ECL of Ru(bpy)₃²⁺ on electrode surface. The molecular beacons (MB) was fixed to SiO₂@Ru−CS−GO by glutaraldehyde (GA) using the Schiff reaction between amino groups of chitosan (CS) and MB. The ECL of SiO₂@Ru−CS−GO was depressed greatly by the Fc@AuNPs labelled at the end of MB, then, a stronger ECL was observed when the distance between Fc@AuNPs and SiO₂@Ru−CS−GO increased after the hybridization of target DNA with MB. Under optimum conditions, the restored ECL intensity increased linearly with the target DNA concentration in the range of 1.0×10⁻¹⁶∼1.0×10⁻¹⁰ mol ⋅ L⁻¹, and the limit of detection (LOD) is 1.4×10⁻¹⁷ mol ⋅ L⁻¹. The proposed method exhibits acceptable stability and reproducibility. In general, the constructed HCV biosensor can be used for the sensitive detection of HCV in human serum, suggesting potential application prospects in bioanalysis.     

鲁米诺在铂电极上阳极电致化学发光的机理研究

研究了碱性鲁米诺溶液在多晶铂电极上的阳极电致化学发光(ECL)行为,观察到电极的预极化处理和溶解氧跟发光峰强度和峰形有直接关系。结合XPS谱图和Pt,Pt|S~a~d~s修饰电极的循环伏安特性,给出了鲁米诺阳极ECL两个发光通道的可能反应机理:(1)鲁米诺阴离子在表面有新鲜Pt原子的电极上氧化生成鲁米诺自由基,然后迅速与溶液中的氧反应形成0.22V(vs.Ag)处的发光肩峰;(2)电极表面的铂氧化物能加速原子态氧的发生过程,并增大0.60V(vs.Ag)附近ECL主峰的发光强度。     

Electrochemiluminescence for probing interactions between a mimic enzyme and biological molecules

The present work proposed a novel ECL protocol to probe the interactions between mimic enzymes and small biological molecules. Iron(II) phthalocyanine (FePc) and two imidazoles (imidazole and histidine) were chosen as model molecules of mimic enzyme and small biological molecules, respectively. The interactions between FePc and the imidazoles were probed by a sensitive luminol–O₂ ECL system. Before complexing with the imidazoles, FePc can inhibit luminol–O₂ ECL due to its electrocatalysis towards O₂, however, after complexing with the imidazoles, FePc decreases the electrocatalysis, leading to the observation of an enhanced luminol–O₂ ECL. Additionally, the proposed protocol enables detection limits of 1.0 × 10^?8 mol L^?1 and 1.0 × 10^?7 mol L^?1 to be achieved, respectively, for imidazole and histidine under the physiological pH condition (pH 7.4).     

Electrogenerated Chemiluminescence (ECL) Determination of Ephedrine with a Self-Assembly Multilayer Ni(II)-Polyluminol Modified Electrode

By combining the layer-by-layer (LBL) self-assembly technique with the electrochemical polymerization method, multilayer Ni(II)-polyluminol films were modified on the surface of a vaseline-impregnated graphite electrode. It was found that, compared with an electrode modified by direct electrochemical polymerization, this modified electrode offered a suitable ECL reaction micro-environment created by the special multilayer films, which was beneficial to the ephedrine hydrochloride enhancing effect for luminol ECL intensity. The ECL enhancing effect of ephedrine hydrochloride on the electro-oxidation luminol was improved on this modified electrode. Based on this finding, a new sensitive ECL method was developed for ephedrine hydrochloride determination under the optimal conditions. At the same time, a new idea is proposed for improving the analytical performance of the luminol ECL system by modifying the ECL reaction micro-environment with the layer-by-layer self- assembly method. Under the optimum experimental conditions, the ephedrine hydrochloride concentration in the range of 2.0 × 10⁻⁸–7.0 × 10⁻⁶ mol L⁻¹ was proportional to the enhanced ECL signal, and it offered an 8.0 × 10⁻⁹ mol L⁻¹ detection limit for ephedrine hydrochloride.     

Enhanced luminol electrochemiluminescence triggered by an electrode functionalized with dendrimers modified with titanate nanotubes

We have constructed a novel electrochemiluminescence (ECL) platform by functionalizing a poly(amidoamine) dendrimer (PAAD) with titanate nanotubes (TiNTs). The PAAD has an open spherical structure that possesses a high density of active groups and thus favors mass transport, while the TiNTs possess excellent electronic conductivity and thus can promote electron transfer on the surface of a glassy carbon electrode (GCE). A study on the intensity and stability of the ECL of luminol on the modified GCE revealed a substantial improvement compared to that of a bare GCE. The effects of the concentration of TiNTs, the pH value of the solution, and of electrochemical parameters on the intensity of the ECL of luminol were studied and resulted in a sensitive ECL sensor for hydrogen peroxide (H₂O₂) that works in the concentration range of 1 nM to 0.9 μM. The scavenging effect of superoxide dismutase (SOD) on the H2O2 electrode ECL was then exploited to design a biosensor for the determination of SOD in concentrations between 50 and 500 nM.