一种基于磁性石墨烯的纸基电化学发光夹心免疫分析方法

基于电化学发光及磁悬浮免疫分析策略,结合磁性石墨烯独特的物理化学特性以及纸基电极价格低廉、样品用量少的优势,建立了一种新型免疫分析方法.以人免疫球蛋白G(IgG)为分析物,采用1-乙基-3-(3-二甲基氨丙基)-碳化二亚胺/N-羟基硫代琥珀酰亚胺(EDC/NHS)法将一抗(Ab1,捕获抗体)固定在磁性石墨烯上,通过直接标记法进行二抗(Ab2,信号抗体)的电化学发光试剂标记,采用磁悬浮夹心免疫技术最大程度减少非特异性吸附,通过纸基电化学发光检测技术测定目标物的浓度.考察了捕获抗体及信号抗体的固定(标记)效果,发现采用的磁性石墨烯不仅提高了免疫物质的负载量,还可以促进电子传递,构建的磁悬浮纸基电化学发光夹心免疫分析法的电化学发光响应峰面积在0.32~1000 ng/mL浓度范围内,与IgG浓度对数值呈良好的线性关系,检出限为6.4 pg/mL.本方法可实现IgG的定量检测,在低成本、快速免疫检测领域有一定的应用前景.     

氧化钙改性高岭土对垃圾渗滤液中氨氮的去除研究

采用氧化钙对高岭土进行改性,并用XRD、SEM和FT-IR对改性高岭土进行了表征。将改性高岭土应用于垃圾渗滤液的处理,考察了改性高岭土投加量、渗滤液初始pH、时间等因素对氨氮去除效果的影响,并对其吸附机理进行了研究。结果表明,氧化钙改性高岭土的产物主要是胶凝材料水化物(硅铝酸钙和含Al的C-S-H凝胶),形貌为蜂窝状;向氨氮含量为3520mg/L、pH为7.53~7.80的垃圾渗滤液中投加160g/L吸附剂,吸附60min,氨氮的去除率达82.66%,吸附量为18.19mg/g。氧化钙改性高岭土对氨氮的吸附符合Langmuir等温模型,动力学上符合准二级动力学方程,其相关系数分别为0.9678,0.9989。同时,该吸附过程包含了膜扩散和颗粒内扩散。     

一种改进的变结构控制器在转台中的应用

针对变结构控制的抖振问题,本提出了一种新的解决方案,采用多切换面的改进变结构控制,在保证了理想滑动模态的抗干扰能力强、鲁棒性好的优点的同时,很好的削弱了系统抖振。仿真结果表明,这种控制规律应用在转台上取得了良好的控制效果。     

On the equivalence of the Wilson element and the generalized hybrid element

In this paper the equivalence of the generalized hybrid element and the modified Wilson element, which is derived by the generalized hybrid method, is proved. The project is supported by the National Natural Science Foundation of China     

A Simple and Sensitive Method for the Detection of Trace Pb(II) and Cd(II) based on Nafion‐coated Antimony Film Electrode

Nafion‐coated antimony film electrode (NCAFE) was prepared in situ by simultaneously plated antimony with analytes, and applied to the determination of trace Pb(II) and Cd(II) in non‐deaerated solutions by differential pulse anodic stripping voltammetry (DPASV). Various experimental parameters, which influenced the response of the NCAFE to those metals, were thoroughly optimized and discussed. The results indicated that the sensitivity and resistance to surfactants at the NCAFE were remarkably improved with relative to the antimony film electrode (AFE). In the presence of 5 mg·L^?1 gelatin, the peak heights at the NCAFE showed 4‐fold enhancement for Pb and a 9‐fold enhancement for Cd over a bare AFE. Reproducibility of the sensor was satisfactory, and the relative standard deviations were 4.8% for 20 μg·L^?1 Pb and 3.2% for 25 μg·L^?1 Cd (n=15) with preconcentration time of 180 s. The determination limits (S/N=3) of this sensor were determined to be 0.15 μg·L^?1 for Pb and 0.30 μg·L^?1 for Cd with accumulation time of 300 s. The NCAFE was successfully applied to determining Pb(II) and Cd(II) in vegetable and water samples with satisfactory results.     

Determination of captopril in patient human urine using ferrocenemonocarboxylic acid modified carbon nanotubes paste electrode

<正>In this work,we describe a new strategy for the electrochemical determination of captopril(CA) using ferrocenemonocarboxylic acid as a mediator and multiwall carbon nanotubes as sensors in aqueous solution at pH 7.0.The diffusion coefficient(D),and the kinetic parameters such as electron transfer coefficient(α).and heterogeneous rate constant(k_h),for CA were also determined using electrochemical approaches.Under the optimized conditions,the electrocatalytic oxidation peak current of captopril showed two linear dynamic ranges with a detection limit of 0.3×10~(-6) mol L~(-1) captopril.The linear calibration range was 0.8×10~(-6) to 65×10~(-6) mol L~(-1) using cyclic voltammetry.Finally,this modified electrode was also examined as a selective,simple and precise new electrochemical sensor for the determination of captopril in real samples such as drug and patient human urine.     

Tetracycline selective electrode based on molecularly imprinted polymer particles

<正>Tetracycline selective electrode using molecularly imprinted polymer particles as quasi-ionophore was constructed the first time, and its performance was carefully characterized.Due to the specific recognition of tetracycline by the particles,the selectivity coefficients for routine interferences were less than 10~(-4).Benefited from the absence of tetracycline in the sensitive membrane and the optimized composition of the inner filling solution,the limit of detection of the electrode was reduced to about 2.5×10~(-8) mol/ L.It exhibited a good electrode slope 57.6 mV/decade near the theoretical Nernstian one,with a wide linear working range from 6.0×10~(-8) to 1.0×10~(-3) mol/L.The fabricated electrode should be used in pH 2-4,response time of which was less than 200 s when the concentration of tetracycline was higher than 1.0×10~(-6) mol/L and no more than 30 min at the concentration of 1.0×10~(-8) mol/L.     

Electrocatalytic oxidation of methanol at platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes

<正>The electrocatalytic oxidation of methanol at the platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes (Eu-Fe film) was investigated for the first time by cyclic voltammetry.Compared with the bare platinum electrode,the results showed that the modified electrode had excellent electrocatalytic activity for the oxidation of methanol;the oxidation peak potential shifted more negatively and the peak current increased about twenty times.The electrooxidation of methanol at the modified electrode with Eu-Fe cyanide-bridged binuclear complexes material exhibited the better tolerance capacity to poison of intermediate species;the peak current was proportional to the concentration of methanol in the range of 0.5-2.0mol/L (R~2 = 0.9991,n =7),which was a comparatively wider linear range.Moreover,based on the linear relationship between the peak current and the square root of scan rate,electrocatalytic oxidation process of methanol was confirmed to be a diffusion control process.Furthermore,according to the counting of electron transfer number(n_α) in the rate-limiting step and the slope of linear equation between acidity of electrolyte and the oxidation peak potential(E_p),the possible mechanism of the electrooxidation of methanol at the modified electrode was primarily discussed.     

A selective voltammetric detection for dopamine using poly (gallic acid) film modified electrode

<正>The electrochemistry behavior of dopamine was investigated by cyclic voltammetry and differential pulse voltammetry at a poly (gallic acid) film modified glassy carbon electrode.Two electrons and two protons participated in the diffusion-controlled electrocatalytic oxidation of dopamine with a diffusion coefficient of 2.186×10~(-5) cm~2/s.The interference of ascorbic acid with the determination of dopamine could be efficiently eliminated.This work provided a simple approach to selectively and sensitively detect dopamine in the presence of high concentration of ascorbic acid.