Use of a poly(4,4′-diaminobiphenyl) chemically modified electrode as a pH sensor

A chemically modified electrode (CME) for use as a potentiometric pH sensor was constructed by electropolymerizing a poly(4,4′-diaminobiphenyl) coating on a platinum electrode. The resulting CME gave a linear response to pH in the range 1–12 with a slope of ?56 mV pH^?1. The CME functioned well in titration experiments and in pH measurements. No significant interference of a coexisting redox couple with the pH measurements was observed. The mechanism of the pH response of the CME is considered.     

双酶电极测定血清中抗坏血酸的研究

本文将抗坏血酸氧化酶和过氧化酶固定在玻碳电极上,制成双酶生物传感器。该生物传感器具有选择性好,灵敏度高、响应快等优点。     

Fe2O3@Au core/shell nanoparticle-based electrochemical DNA biosensor for Escherichia coli detection

A Fe₂O₃@Au core/shell nanoparticle-based electrochemical DNA biosensor was developed for the amperometric detection of Escherichia coli (E. coli). Magnetic Fe₂O₃@Au nanoparticles were prepared by reducing HAuCl₄ on the surfaces of Fe₂O₃ nanoparticles. This DNA biosensor is based on a sandwich detection strategy, which involves capture probe immobilized on magnetic nanoparticles (MNPs), target and reporter probe labeled with horseradish peroxidase (HRP). Once magnetic field was added, these sandwich complexes were magnetically separated and HRP confined at the surfaces of MNPs could catalyze the enzyme substrate and generate electrochemical signals. The biosensor could detect the concentrations upper than 0.01 pM DNA target and upper than 500 cfu/mL of E. coli without any nucleic acid amplification steps. The detection limit could be lowered to 5 cfu/mL of E. coli after 4.0 h of incubation.     

Sensitive Voltammetric Detection of Trace Heavy Metals in Real Water Using Multi‐Wall Carbon Nanotubes/Nafion Composite Film Electrode

Multi‐wall carbon nanotubes (MWCNTs) and Nafion composite film (MWCNTs/Nafion) were used for fabricating electrochemical sensors for the voltammetric detection of trace lead(II) and cadmium(II) in several water samples. The morphology and structure of MWCNTs/Nafion film were characterized by scanning electron microscopy (SEM) and infrared spectrum (IR). The electron transfer of MWCNTs/Nafion composite film was examined by cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS). Various experimental parameters, which influenced the response of MWCNTs/Nafion/GC to target metals, were optimized. The results showed that the synergistic effect was obtained on the MWCNTs/Nafion/GC whose sensitivity and stability were better than those of Nafion‐coated electrode (Nafion/GC) or CNTs/GC. Stability of the Pb(II) and Cd(II) stripping signals was excellent with relative standard deviations (RSD) within 5% (n=10) from one electrode preparation to another, and RSD of 30 µg·L^?1 Pb(II) and Cd(II) were 2.8% and 3.2% for 20 repeated analysis on one single CNTs/Nafion/GC. Over 50 runs, the stability of Pb and Cd detection at the MWCNTs/Nafion conposites electrode was still satisfactory with RSD lower than 6.0%. The determination limits (S/N=3) of the proposed method were determined to be 100 ng·L^?1 for Pb and 150 ng·L^?1 for Cd. Finally, the MWCNTs/Nafion/GC was successfully applied to determine Pb(II) and Cd(II) in different water samples with recoveries of 97%–103% for Pb and 96%–104% for Cd.     

Glucose Biosensor Based on the Fabrication of Glucose Oxidase in the Bio-Inspired Polydopamine-Gold Nanoparticle Composite Film

A highly efficient enzyme immobilization method has been developed for electrochemical biosensors using polydopamine films with gold nanoparticles (AuNPs) embedded. This simple enzyme fabrication method can be performed in very mild conditions and stored in a long time with high bioactivity. The fabricated amperometric glucose biosensor exhibited a high and reproducible sensitivity, wide linear dynamic range and low limit of detection (LOD) (0.1 μmol·L^?1). A low value of 1.5 mmol·L^?1 for the apparent Michaelis‐Menten constant K^app_M was obtained. The high sensitivity, wide linear range, good reproducibility and stability make this biosensor a promising candidate for portable amperometric glucose biosensor.     

阳极溶出催化伏安法测定L—DOPA

我们用Nafion修饰电极阳极溶出伏安法测定抗癌药左旋多巴(L-DOPA)获得了满意的结果。本文报导由于Na_2SO_3对左旋多巴的催化氧化作用,可使测定灵敏度进一步提高,检测下限达5.0×10~(-8)mol/L。(一)测定步骤的确定     

Nafion-甲基紫精修饰电极抗坏血酸氧化酶生物传感器的研究

本文用Nafion-甲基紫精修饰电极为基底,以牛血清白蛋白和戊二醛为交联剂,将抗坏血酸氧化酶固定在电极上,制成修饰电极抗坏血酸氧化酶生物传感器。用这种生物传感器测定人体血清中抗坏血酸,线性范围在7.5×10~(-4)～7.5×10~(-7)mol/L之间,响应时间为5s,检测下限为2.5×10~(-7)mol/L。该传感器具有选择性好、灵敏度高和响应时间短等特点。     

三辛基氧化膦修饰电极三元络合物体系测定铕(Ⅲ)的研究

本文报道了三辛基氧化膦(TOPO)修饰旋转圆盘玻碳电极对痕量铕 (Ⅱ)的富集与测定的研究。在嚷吩甲酰三氟丙酮(HTTA),存在的HAc-NaAc底液中,由于协同络合作用,在电极表面形成Eu(TTA)3(TOPO)2三元络合物,从而将铕(Ⅱ)富集在电极表面。采用徽分脉冲阴极溶出伏安法,最低检出限可达0.01ng/ml,铕(Ⅱ)在0.04—2.60 ng/ml范围内与峰高成线性关系。     

微渗析活体取样-高效液相色谱电化学检测法测定鼠脑中的单胺类神经递质

采用微渗析活体取样技术和高效液相色谱电化学检测法,测定了鼠脑纹状体中的3种单胺类神经递质多巴胺(DA)、3,4二羟基苯乙酸(DOPAC)和5羟吲哚乙酸(5HIAA)。在3.0×10-8～1.0×10-5mol/L浓度范围内,DA、DOPAC和5HIAA的浓度分别与氧化峰的峰电流呈良好的线性关系。通过在灌流液中加入1.0×10-5mol/L的NO释放剂硝普钠(SNP),研究了NO对DA释放的影响,结果表明:受NO刺激后纹状体中DA的量为基础水平的150%。     

An Ni(chitin)2 modified nitric oxide microsensor

The development of a simple, sensitive, selective, and stable amperometric nitric oxide microsensor is described. It is based on Ni(chitin)₂ mediators immobilized on a platinum, Nafion modified electrode. The detection of NO is based on the Ni(chitin)₂ catalysis of NO oxidation at an anodic potential of +0.74 V (vs. SCE). The catalytic peak current is linear for a NO concentration in the range of 8.5 × 10^–8 mol/L to 1.5 × 10^–5 mol/L, with a correlation coefficient of 0.9992. The detection limit of the microsensor is 5.0 × 10^–8 mol/L. It is suitable for the direct measurement of NO in biological systems. Received: 5 February 1999 / Revised: 15 June 1999 / Accepted: 17 June 1999