Electrogenerated chemiluminescence of luminol on a gold-nanorod-modified gold electrode

Electrogenerated chemiluminescence (ECL) of luminol on a gold-nanorod-modified gold electrode was studied, and five ECL peaks were obtained under conventional cyclic voltammetry in both neutral and alkaline solutions. Among them, four ECL peaks (ECL-1-4) were also observed on a gold-nanosphere-modified gold electrode, but the intensities of these ECL peaks were enhanced about 2-10-fold on a gold-nanorod-modified gold electrode in neutral solution. One new strong ECL peak (ECL-5) was obtained at -0.28 V (vs SCE) on a gold-nanorod-modified gold electrode in both neutral and alkaline solutions and enhanced with an increase in pH. In strong alkaline solutions, ECL-1 and ECL-2 on a gold-nanosphere-modified electrode were much stronger than those on a gold-nanorod-modified gold electrode, while ECL-3-5 appeared to only happen on a gold-nanorod-modified gold electrode. The emitter of all the ECL peaks was identified as 3-aminophthalate. The ECL peaks were found to depend on the scan direction, the electrolytes, the pH, and the presence of O(2) and N(2). The reaction pathways for ECL-4 have been further elucidated, and the mechanism of the new ECL peak (ECL-5) has been proposed. The results indicate that a gold-nanorod-modified gold electrode has a catalytic effect on luminol ECL different from that of a gold-nanosphere-modified gold electrode, revealing that the shape of the metal nanoparticles has an important effect on the luminol ECL behavior. The strong ECL of luminol in neutral solution obtained on a gold-nanorod-modified electrode may be used for the sensitive detection of biologically important compounds in physiological conditions.     

Gold Nanoparticle Modified Electrodes Show a Reduced Interference by Cu(II) in the Detection of As(III) Using Anodic Stripping Voltammetry

Interference by Cu(II) causes serious problems in the detection of As(III) using anodic stripping voltammetry at gold electrodes. The behavior of Cu(II) and As(III) were examined at both a gold macro electrode and two kinds of gold nanoparticle modified electrodes, one where gold particles are deposited on glassy carbon (GC) and the other where basal plane pyrolytic graphite (BPPG) is the substrate. The sensitivity of As(III) detection was higher on gold nanoparticle modified electrodes than those on a macro gold electrode by up to an order of magnitude. In addition, the stripping peak of As(III) was narrower and more symmetric on a gold nanoparticle‐modified GC electrode, leading to analytical data with a lower limit of detection. At a macro gold electrode, the peak currents of Cu(II) were higher than those on gold nanoparticle modified electrodes. Accordingly, through the use of gold nanoparticle modified electrodes, the effect of copper interference to the arsenic detection can be reduced.     

巯基化改性壳聚糖在电化学生物传感器制备中的应用

以壳聚糖、N-乙酰-L-半胱氨酸(NAC)为原料,以1-羟基苯并三唑(HOBt)和1-乙基-3-(3-二甲基胺丙基)碳化二亚胺盐酸盐(EDAC)为缩合剂,合成功能化壳聚糖衍生物巯基壳聚糖(CHS-NAC).用红外光谱(FTIR)、核磁共振(1H-NMR)及X射线衍射(XRD)对其结构进行表征,用Ellman’s试剂通过标准曲线法测得巯基含量.利用CHS-NAC的黏附性,通过层层吸附的方法将CHS-NAC、纳米金及细胞色素c分别修饰到玻碳电极(GC)上,通过扫描电子显微镜(SEM)对修饰电极表面的形貌进行了观察,采用循环伏安和电化学阻抗研究了不同修饰膜电极的电化学行为,及扫描速率对细胞色素c修饰电极的影响,并开展了对过氧化氢的电催化分析.实验结果表明,CHS-NAC能高效地将纳米金及细胞色素c固定在电极表面,并能有效发挥纳米金辅助转移电子及细胞色素c对过氧化氢催化的能力.     

Electrochemical synthesis of gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode and their application

Gold nanoparticles on the surface of multi-walled carbon nanotubes with glassy carbon electrode were prepared using electrochemical synthesis method. The thin films of gold Nanoparticles/multi-walled carbon nanotubes were characterized by scanning electron microscopy, powder X-ray diffraction, and cyclic voltammetry. Electrochemical behavior of adrenaline hydrochloride at gold nanoparticles/multi-walled carbon nanotube modified glassy carbon electrode was investigated. A simple, sensitive, and inexpensive method for determination of adrenaline hydrochloride was proposed.     

Gold nanoparticle-modified glassy carbon electrode for electrochemical investigation of aliphatic di-carboxylic acids in aqueous media

The electrochemical reduction of di-carboxylic acids; oxalic, succinic, malic, and tartaric have been studied on the gold nanoparticles modified electrode in aqueous media solution of 0.1 M KCl. Gold nanoparticle (Au_NPs)-modified electrodes were prepared by the electrodeposition with cyclic voltammetric method onto glassy carbon electrode in acidic media. The surface morphology of the electrodeposited gold nanoparticles was examined by SEM. Also, the electrochemical properties of the prepared electrodes were investigated with different electrochemical techniques; cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. Cyclic voltammetric, chronoamperometric, and electrochemical impedance spectroscopic techniques were used for investigating the electrochemical behavior of the particulate acids. The modification of the electrode with Au nanoparticles (Au_NPs) enables the appearance of cyclic voltammogram peaks completely clear and sharp for the acids under investigation in comparison with the poor behavior of them in absence of the modification. All acids undergo totally irreversible redox reaction in neutral and acid media. The cyclic voltammetric response of the investigated acids is sensitive to pH, as well as of the scan rate. Each acid has a different reduction peak position from the other acids depending on the structure of the acid undergo the electroreduction process. Further, the lowest unoccupied molecular orbital energies of the investigated acids have been theoretically evaluated and are compared with their electroreduction potential peaks.     

Electrochemical assembling of methionine-gold nanoparticles and catalysis on the surface of glassy carbon electrode

In this paper cyclic voltammetry was used for the synthesis of linear array spherical gold nanoparticles on the surface of glassy carbon electrode using methionine as a stable reagent. The methionine-gold nanoparticles on the surface of glassy electrode were obtained. The methionine-gold nanoparticles were characterized by cyclic voltammetry, scanning electron microscopy, energy dispersive spectrometry and powder X-ray diffraction. Electrochemical behavior of methionine at methionine-gold nanoparticle modified electrode was investigated. It was demonstrated that the methionine-gold nanoparticles can catalyze electrochemical transformations of methionine.     

The enhanced electrochemiluminescence of luminol on the nickel phthalocyanine modified electrode

A glassy carbon electrode (GCE) modified with nickel(II) tetrasulfophthalocyanine (NiTSPc) and Nafion was used for the investigation of the catalytic oxidation of luminol. The modified electrode was found to much more effectively improve the emission of electrochemiluminescence(ECL) of luminol in a solution containing hydrogen peroxide. The enhanced ECL signal corresponded to the catalytic oxidation of both luminol and H(2)O(2) by NiTSPc. Attached Ni(II) on GCE was oxidised to Ni(III) and then used as the catalyst for the chemiluminescence of luminol. The enhanced stability of the ECL signal with Nafion would mainly result from the prevention of the dissolution of NiTSPc and the adsorption of the oxidation product of luminol on the electrode surface. The proposed method enables a detection limit for luminal of 6.0 x 10(-8) mol L(-1) to be achieved in the presence of H(2)O(2) in the neutral solution. The enhanced ECL intensity had a linear relationship with the concentration of luminol in the range of 1.0 x 10(-7)-8.0 x 10(-6) mol L(-1).     

Glassy Carbon Electrode Modified with Citrate Stabilized Gold Nanoparticles for Sensitive Arsenic (III) Detection

The electrochemical detection of As(III) was investigated on the novel citrate stabilized gold nanoparticle modified glassy carbon electrode (AuNPs/GCE) in 1 M HCl by square wave anodic stripping voltammetry. AuNPs/GCE was prepared by simply casting citrate stabilized gold nanoparticles onto the well-polished glassy carbon electrode. Gold modification was evaluated by cyclic voltammetry, while transmission electron microscopy and UV-vis Spectroscopy revealed the size and distribution of gold nanoparticles. Anodic stripping voltammetry was performed with the modified electrode in As(III) solution. Electrochemical experiments proved that AuNPS/GCE exhibited good performance for As(III) analysis, the linear range were obtained between 0.05 and 1 ppb for trace level of As(III) as well as 1 to 15 ppb, with a limit of detection of 0.025 ppb. In terms of reproducibility, the precision of the aforementioned method in %RSD was calculated at 7.78% (n = 10), and the repeatability of the proposed method was calculated to be 1.59%. The application of the method to analyze As(III) in tap water was investigated.     

纳米金/碳纳米管复合材料修饰电极催化鲁米诺电致发光体系的研究

制备了纳米金/多壁碳纳米管(MWNT)复合材料修饰电极,并将此电极应用于鲁米诺电化学发光体系.电化学发光实验表明,此复合材料修饰电极同时具备了纳米金和碳纳米管的催化性能.此外通过电极活性表面积测算、电化学交流阻抗实验等方法研究了纳米金和碳纳米管在此体系催化过程中的作用.纳米金/碳纳米管修饰电极具有良好的重现性,可以广泛应用于鲁米诺电化学发光测定体系.     

纳米金–壳聚糖修饰电极循环伏安法测定抗坏血酸

介绍纳米金–壳聚糖修饰电极的制备方法及其测定抗坏血酸的分析应用。采用电沉积方法,将氯金酸与壳聚糖的混合电解液直接共沉积,制备了壳聚糖–纳米金修饰玻碳电极的电化学传感器。利用循环伏安法研究了抗坏血酸浓度、p H值等对抗坏血酸在修饰电极上的电化学行为的影响。实验结果表明,修饰电极对抗坏血酸具有良好的电催化氧化作用,抗坏血酸浓度在5×10~(–5)~1×10~(–3) mol/L范围内线性良好,回归方程为I_p=0.433 8c+0.881 9,相关系数为0.998 71。该法可指导纳米金–壳聚糖修饰电极的制备及抗坏血酸含量的测定。     

Studies on electrochemical oxidation of azithromycin and its interaction with bovine serum albumin

A novel nanoparticle film modified electrode has been constructed using a glassy carbon electrode (GCE) coated with a carbon nanotube-dihexadecylphosphate (DHP) film. This modified electrode exhibits an enhanced effectiveness for the oxidation of azithromycin. A method is also described for the evaluation of azithromycin-bovine serum albumin (BSA) interaction. The electrochemical behavior of azithromycin as well as its interaction with BSA at this nanoparticle film electrode has been investigated by cyclic voltammetry, linear sweep voltammetry, differential pulse voltammetry and chronocoulometry. The binding number and association constant between azithromycin and bovine serum albumin have been obtained.     

芦丁在铂纳米/碳纳米管修饰电极上电化学行为研究

通过电沉积的方式在多壁碳纳米管(MWCNTs)修饰玻碳电极表面上沉积铂(pt)纳米粒子,并运用循环伏安法(CV)、示差脉冲伏安法(DPV)探讨了芦丁在铂纳米/碳纳米管/玻碳电极上的电化学行为.实验结果表明,芦丁在该修饰电极上呈现一对良好氧化还原峰,其氧化峰电流与浓度在3.2×10(-8)～1.2×10(-5)mol/L...     

电氧化异丙肾上腺素的纳米复合电催化剂：用作传感器

在金纳米粒子(AuNPs)上经苯硫酚衍生物(3,4二羟基苯基-偶氮-苯硫酚, DAT)自组装制得了一种新型纳米复合物,用于修饰玻璃碳电极(GCE/AuNP-DAT).采用循环伏安法研究了该新型电极的性质,并将其用作异丙肾上腺素(IP)电催化剂,考察了该纳米复合物的电催化活性,从而得到反应机理和催化反应速率常数.由于GCE/AuNP-DAT电极对尿酸氧化没有电催化活性,因此可将IP的氧化信号从该改进电极中分离出来,从而排除了尿酸对IP测定的干扰.该电极可作为传感器,当用于差动脉冲伏安法测定IP时,线性动态范围为1.0–1500.0μmol/L,检测极限为0.46μmol/L.     

Synthesis, characterization, and electrochemiluminescence of luminol-reduced gold nanoparticles and their application in a hydrogen peroxide sensor

It was found that chloroauric acid (HAuCl(4)) could be directly reduced by the luminescent reagent luminol in aqueous solution to form gold nanoparticles (AuNPs), the size of which depended on the amount of luminol. The morphology and surface state of as-prepared AuNPs were characterized by transmission electron microscopy, UV/visible spectroscopy, X-ray photoelectron spectroscopy, FTIR spectroscopy, and thermogravimetric analysis. All results indicated that residual luminol and its oxidation product 3-aminophthalate coexisted on the surface of AuNPs through the weak covalent interaction between gold and nitrogen atoms in their amino groups. Subsequently, a luminol-capped AuNP-modified electrode was fabricated by the immobilization of AuNPs on a gold electrode by virtue of cysteine molecules and then immersion in a luminol solution. The modified electrode was characterized by cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy. The as-prepared modified electrode exhibited an electrochemiluminescence (ECL) response in alkaline aqueous solution under a double-step potential. H2O2 was found to enhance the ECL. On this basis, an ECL sensor for the detection of H2O2 was developed. The method is simple, fast, and reagent free. It is applicable to the determination of H2O2 in the range of 3x10(-7)-1x10(-3) mol L(-1) with a detection limit of 1x10(-7) mol L(-1) (S/N=3).     

Determination of catecolamines on electrodes modified with multiwalled carbon nanotubes

The electrochemical behavior of several biologically active catecolamines in studied on a glassy carbon electrode with the surface preliminarily modified by a composite film containing preliminarily carboxylated multi-walled carbon nanotubes (MWNT). The coatings are characterized by the methods of cyclic voltammetry and scanning microscopy. It is shown that the use of hybrid composites prepared by immobilizing MWNT and gold nanoparticles into the film of poly(isonicotinic) acid provides the high diffusion permeability of the surface layers and the efficiency of the electron transfer as regards catecolamines. The possibility of using these electrodes for selective determination of these substances in drugs widely used in the modern practical medicine is demonstrated.     

Detection of DNA immobilized on bare gold electrodes and gold nanoparticle-modified electrodes via electrogenerated chemiluminescence using a ruthenium complex as a tag

Electrogenerated chemiluminescence (ECL) for DNA hybridization detection is demonstrated based on DNA that was self-assembled onto a bare gold electrode and onto a gold nanoparticles modified gold electrode. A ruthenium complex served as an ECL tag. Gold nanoparticles were self-assembled on a gold electrode associated with a 1,6-hexanedithiol monolayer. The surface density of single stranded DNA (ssDNA) on the gold nanoparticle modified gold electrode was 4.8?×?10¹⁴ molecules per square centimeter which was 12-fold higher than that on the bare gold electrode. Hybridization was induced by exposure of the target ssDNA gold electrode to the solution of ECL probe consisting of complementary ssDNA tagged with ruthenium complex. The detection limit of target ssDNA on a gold nanoparticle modified gold electrode (6.7?×?10^?12 mol L^?1) is much lower than that on a bare gold electrode (1.2?×?10^?10 mol L^?1). The method has been applied to the detection of the DNA sequence related to cystic fibrosis. This work demonstrates that employment of gold nanoparticles self-assembled on a gold electrode is a promising strategy for the enhancement of the sensitivity of ECL detection of DNA.     

基于还原石墨烯/纳米银复合材料的电化学传感器测定双酚A

石墨烯特有的褶皱层状结构以及银纳米粒子良好的催化性能,使其在电化学方面具有良好的应用潜能.本研究以柠檬酸钠为还原剂,通过水热反应原位制备出还原石墨烯/纳米银复合材料(rGO/AgNPs),用于修饰玻碳电极,研究了双酚A的电化学行为.循环伏安法(CV)和方波伏安法(SWV)的实验结果表明,双酚A可以在rGO/AgNPs修饰电极表面发生快速的氧化还原反应,基于此实现了对双酚A的高灵敏检测.在最优条件下,双酚A的氧化峰电流与其浓度在0.1~40.0μmol/L范围内呈良好的线性关系(r2=0.996),检出限为50.7 nmol/L(S/N=3).将其用于实际环境和塑料样品中双酚A的检测,回收率为91.7%~102.9%.     

空壳纳米金修饰的新型DNA传感器

利用新型材料金纳米空球, 通过层层修饰的技术, 分别将壳聚糖、空壳纳米金、L-半胱氨酸、细胞色素c以及ssDNA探针修饰到玻碳电极表面, 制备了一种新型的DNA生物传感器. 以紫外及透射电子显微镜(TEM)表征了空壳纳米金, 以循环伏安法、阻抗谱图等电化学方法研究了传感器的特性, 通过原子力显微镜方法观察了该DNA生物传感器不同层之间的形态差异. 结果表明, 该修饰电极所吸附的ssDNA探针为1.672×10^―10 mol•cm^－2. 在指示剂柔红霉素的帮助下, DNA探针可与互补的DNA进行杂交, 借此以微分脉冲伏安法测定DNA.     

Electrochemiluminescent detection of the hybridization of oligonucleotides using an electrode modified with nanocomposite of carbon nanotubes and gold nanoparticles

We report on an electrochemiluminescent (ECL) sensing technique for the detection of the hybridization between oligonucleotides. A glassy carbon electrode was first functionalized with a composite prepared from gold nanoparticles and carbon nanotubes, and a sensor was then constructed by immobilizing the probing oligonucleotide. The ECL of luminol acts as the sensing signal. It is quenched, to a different degree, by the hybridized double strands of the oligonucleotide depending on the match status. The slope of the ECL response as a function of the status of hybridization drops with increasingly matched hybridization. The response is attributed to the interaction between luminol and the strands of oligomers, and also related to the reduction of reactive oxygen species.

聚中性红/纳米二氧化硅复合修饰电极直接测定抗坏血酸

用滴涂法和电化学聚合法制备了聚中性红/纳米二氧化硅修饰电极(PNR/nano-SiO2/GCE),并用循环伏安法和交流阻抗法研究了修饰电极表面的电化学行为。实验表明,该修饰电极对抗坏血酸(AA)表现出良好的电催化氧化性能,探讨了复合修饰电极协同增效作用的机理。用线性扫描伏安法研究了AA浓度与峰电流之间线性关系,在pH2.0的磷酸盐缓冲溶液中,AA氧化峰电流在1.8×10-6～5.0×10-3mol/L浓度范围内呈良好的线性关系,检出限为5.4×10-7mol/L(S/N=3)。该修饰电极制备简单,可用于药品及果蔬食品中抗坏血酸的直接测定。