A Novel Electrogenerated Chemiluminescence (ECL) Sensor Based on Ru(bpy)32+‐Doped Titania Nanoparticles Dispersed in Nafion on Glassy Carbon Electrode

A novel electrogenerated chemiluminescence (ECL) sensor based on Ru(bpy)₃²⁺‐doped titania (RuDT) nanoparticles dispersed in a perfluorosulfonated ionomer (Nafion) on a glassy carbon electrode (GCE) was developed in this paper. The electroactive component‐Ru(bpy)₃²⁺ was entrapped within the titania nanoparticles by the inverse microemulsion polymerization process that produced spherical sensors in the size region of 38±3 nm. The RuDT nanoparticles were characterized by electrochemical, transmission electron and scanning microscopy technology. The Ru(bpy)₃²⁺ encapsulation interior of the titania nanoparticles maintains its ECL efficiency and also reduces Ru(bpy)₃²⁺ leaching from the titania matrix when immersed in water due to the electrostatic interaction. This is the first attempt to prepare the RuDT nanoparticles and extend the application of electroactive component‐doped nanoparticles into the field of ECL. Since a large amount of Ru(bpy)₃²⁺ was immobilized three‐dimensionally on the electrode, the Ru(bpy)₃²⁺ ECL signal could be enhanced greatly, which finally resulted in the increased sensitivity. The ECL analytical performance of this ECL sensor for tripropylamine (TPA) was investigated in detail. This sensor shows a detection limit of 1 nmol/L for TPA. Furthermore, the present ECL sensor displays outstanding long‐term stability.     

Properties of Poly(sodium 4‐styrenesulfonate)‐Ionic Liquid Composite Film and Its Application in the Determination of Trace Metals Combined with Bismuth Film Electrode

A new kind of bismuth film modified electrode to sensitively detect trace metal ions based on incorporating highly conductive ionic liquids 1‐butyl‐3‐methyl‐imidazolium hexafluorophosphate (BMIMPF₆) in solid matrices at glassy carbon (GC) was investigated. Poly(sodium 4‐styrenesulfonate) (PSS), silica, and Nafion were selected as the solid matrices. The electrochemical properties of the mixed films modified GC were evaluated. The electron transfer rate of Fe(CN)₆^4?/Fe(CN)₆^3? can be effectively improved at the PSS‐BMIMPF₆ modified GC. The bismuth modified PSS‐BMIMPF₆ composite film electrodes (GC/PSS‐BMIMPF₆/BiFEs) displayed high mechanical stability and sensitive stripping voltammetric performances for the determination of trace metal cations. The GC/PSS‐BMIMPF₆/BiFE exhibited well linear response to both Cd(II) and Pb(II) over a concentration range from 1.0 to 50 μg L^?1. And the detection limits were 0.07 μg L^?1 for Cd(II) and 0.09 μg L^?1 for Pb(II) based on three times the standard deviation of the baseline with a preconcentration time of 120 s, respectively. Finally, the GC/PSS‐BMIMPF₆/BiFEs were successfully applied to the determination of Cd(II) and Pb(II) in real sample, and the results of present method agreed well with those of atomic absorption spectroscopy.     

Renewable Copper and Silver Amalgam Film Electrodes of Prolonged Application for the Determination of Elemental Sulfur Using Stripping Voltammetry

New, renewable copper (Hg(Cu)FE) and silver (Hg(Ag)FE) based amalgam film electrodes applied for the determination of elemental sulfur using differential pulse cathodic stripping voltammetry are presented. With surface areas adjustable from 1 to 12 mm², both electrodes are characterized by very good surface reproducibility (≤2%) and long‐term stability (a few thousand measurement cycles). The mechanical refreshing of the amalgam film takes about 1–2 seconds. The effects of various factors such as instrumental parameters and the supporting electrolyte composition were optimized. Interferences from sulfides are easily removed by the addition of acid, and bubbling with argon, for Hg(Ag)FE. In the case of Hg(Cu)FE, sulfides did not interfere. The calibration graph is linear within the studied range from 16 ng L^?1 to 4.8 μg L^?1 for Hg(Cu)FE, and up to 6.4 μg L^?1 for Hg(Ag)FE (t_acc=15 s). The correlation coefficients for the two electrodes were at least 0.997. The detection limits for a low concentration of S(0) and t_acc=60 s are as low as 14 ng L^?1 for Hg(Cu)FE and 4 ng L^?1 for Hg(Ag)FE. The proposed method was successfully applied and validated by studying the recovery of S(0) from spiked river water.     

The Influence of the Electrodeposition Conditions on the Electroanalytical Performance of the Bismuth Film Electrode for Lead Determination

The bismuth film is a great promise as a suitable material to replace the mercury electrodes due to its low toxicity and good cathodic potential range. This work studies the influence of the electrodeposition conditions in the morphology and electroanalytical performance of the bismuth film electrodeposited onto copper electrode. The bismuth films were obtained in nitric or hydrochloric acid solutions with and without the presence of sodium citrate. The films were characterized by field emission scanning electron microscopy (FE‐SEM) and scanning electron microscopy with energy dispersive X‐ray spectrometry (SEM‐EDX). The microscopic analysis of the bismuth film obtained in HCl solution with sodium citrate (BIFE‐Cit) showed more homogeneous structure with higher content of bismuth than the film obtained in HCl only (BiFE‐HCl). The BiFE‐Cit exhibited a better analytical performance for lead with good adherence to the copper substrate.     

Iridium Oxide Film Electrodes for Anodic Stripping Voltammetry

The new iridium oxide film electrode, applied for the determination of lead(II), cadmium(II) and copper(II) traces using differential pulse anodic stripping voltammetry (DP ASV) is presented. The electrode display an interesting stripping voltammetric performance which compares with electrodes commonly used in voltammetry. The deposited film is known as anodically electrodeposited iridium oxide film (AEIROF). The AEIROF electrode is characterized by long‐term stability (more than 40 days) and very good reproducibility of the analytical signals in this time (≤12% for 0.5 μM of lead). The regeneration of iridium film is very simple in a time shorter than 60 seconds. The effects of various factors such as: thickness of AEIROF film, preconcentration potential and time, supporting electrolyte composition, potential interferences are optimized. The detection limit for AEIROF film electrode based on glassy carbon for an accumulation time of 30 s is as low as 7 nM for lead(II). The repeatability of the method at a concentration level of the lead(II) as low as 0.5 μM, expressed as RSD is 2.5% (n=10). The proposed method was successfully applied and validated by studying certified reference material CTA‐OTL‐1. Such an attractive use of ‘mercury–free’ ‐ environmentally friendly electrodes offers great promise to measure trace metals.     

Surface Characterization and the Gas Response of a Mixed,Fe2O3?Fe2(MoO4)3, Oxide to Low Concentrations of H2S in Air

The preparation and H₂S sensing potential of thick‐films of a mixed oxide, Fe₂O₃? Fe₂(MoO₄)₃, were investigated. A Fourier‐transform infrared (FTIR) study confirmed the existence of sulfur species at the surface after the interaction of H₂S gas with the mixed oxide. The starting material, β‐FeMoO₄, was synthesized by a solvothermal method, followed by supercritical drying. Heat treatment of this material (oxidation) above 500 °C resulted in the formation of Fe₂O₃? Fe₂(MoO₄)₃ mixed oxide, where Fe₂O₃ was a by‐product. An increase in the conductivity of the films in the presence of H₂S gas (concentration range 1–20 ppm in air) was observed with the simultaneous formation of water and sulfide ions at 225 °C. An improvement of the H₂S sensing potential is obtained, using an intermediate short heat treatment at higher temperature (500 °C) in the beginning of recovery (desorption) phase. This intermediate high temperature, used before every expected exposure to H₂S gas, may contribute the formation of an initial surface coverage of O^2?.     

Galvanostatic Entrapment of Sulfite Oxidase into Ultrathin Polypyrrole Films for Improved Amperometric Biosensing of Sulfite

The entrapment of sulfite oxidase (SOx) into ultrathin polypyrrole (PPy) films of 27–135 nm thickness has been successfully used for amperometric biosensing of sulfite with considerably improved performance. Optimum galvanostatic entrapment was accomplished in an electrolyte‐free solution which contained 0.1 M pyrrole and 5 U/mL of SOx with a polymerization period of 120 seconds and an applied current density of 0.2 mA cm^?2. Evidence of the incorporation and retention of SOx in the ultrathin PPy film was obtained by scanning electron microscopy, cyclic voltammetry and amperometric measurements. Entrapment of the enzyme in a 54 nm thick PPy‐SOx film gave optimum amperometric response for sulfite and enabled the detection of as little as 0.9 μM of sulfite with a linear concentration range of 0.9 to 400 μM. The successful application of the biosensor to the determination of sulfite in beer and wine samples is reported. Comparison with a spectrophotometric method indicates that the biosensor was more superior for the determination of sulfite in red wine.     

花瓣形YBO3∶Eu3+发光薄膜的制备与表征

本文报道了通过水热合成在AAO模板上组装出花瓣形YBO3∶Eu3+薄膜的研究工作.     

Dynamic adsorption and characterization of phospholipid and mixed phospholipid/protein layers at liquid/liquid interfaces

Drop profile analysis tensiometry is applied to study the adsorption dynamics of phospholipids, proteins and phospholipid/protein mixtures at liquid/liquid interfaces. Measurements of the dynamic interfacial tension of phospholipid layers give information on the adsorption mechanism and the structure of the adsorption layer. The equilibrium and dynamic adsorption of pure protein solutions, i.e. human serum album (HSA), beta-lactoglobulin (beta-LG), beta-casein (beta-CA), can be explained well by the thermodynamic model of Frumkin and the diffusion-controlled adsorption theory. The adsorption behavior from mixed phospholipid/protein solutions was also investigated in terms of dynamic interfacial tensions. Interestingly, a "skin-like" folded film of pure protein or phospholipid/protein complex layers can be observed at curved surfaces at the water/oil interfaces. The addition of phospholipids accelerates the formation of the folded structure at the drop surface through co-adsorption of proteins.     

双层铜金属薄膜纳米压痕机械性能的分子动力学模拟

多层金属薄膜的机械性质在纳米组件的设计上是非常重要的.目前,纳米尺度材料的机械性质测量的最主要方法为纳米压痕检测技术.本文应用分子动力学理论对双层铜金属薄膜界面的结构形态与特性进行分析探讨.选用FCC结构单晶铜的(100)面,(110)面和双层铜金属薄膜作为探讨界面性质的材料,进而探讨了单晶铜及双层铜金属薄膜的纳米压痕变形性质.