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Mao S.,Soochow University of China | Long Y.,Soochow University of China | Long Y.,Key Laboratory of Health Chemistry | Li W.,Soochow University of China | And 2 more authors.
Biosensors and Bioelectronics

Ag@C core-shell nano-composites have been prepared by a simple one-step hydrothermal method and are further explored for protein immobilization and bio-sensing. The electrochemical behavior of immobilized horseradish peroxidase (HRP) on Ag@C modified indium-tin-oxide (ITO) electrode and its application as H2O2 sensor are investigated. Electrochemical and UV-vis spectroscopic measurements demonstrated that Ag@C nano-composites provide excellent matrixes for the adsorption of HRP and the entrapped HRP retains its bioactivities. It is found that on the HRP-Ag@C/ITO electrode, HRP exhibited a fast electron transfer process and good electrocatalytic reduction toward H2O2. Under optimum experimental conditions the biosensor linearly responds to H2O2 concentration in the range of 5.0×10-7-1.4×10-4M with a detection limit of 2.0×10-7M (S/N=3). The apparent Michaelis-Menten constant (Kapp M) of the biosensor is calculated to be 3.75×10-5M, suggesting high enzymatic activity and affinity toward H2O2. In addition, the HRP-Ag@C/ITO bio-electrode shows good reproducibility and long-term stability. Thus, the core-shell structured Ag@C is an attractive material for application in the fabrication of biosensors due to its direct electrochemistry and functionalized surface for efficient immobilization of bio-molecules. © 2013 Elsevier B.V. Source

Rao H.,Soochow University of China | Rao H.,Key Laboratory of Health Chemistry | Zhang J.,Soochow University of China | Zhang J.,Key Laboratory of Health Chemistry | And 2 more authors.

A simple and sensitive electrochemiluminescence (ECL) method for the determination of etamsylate has been developed by coupling an electrochemical flow-through cell with a tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)3 2+)-Nafion-modified carbon electrode. It is based on the oxidized Ru(bpy)3 2+on the electrode surface reacting with etamsylate and producing an excellent ECL signal. Under optimized experimental conditions, the proposed method allows the measurement of etamsylate over the range of 8-1000ng/mL with a correlation coefficient of r =0.9997 (n = 7) and a limit of detection of 1.57 ng/mL (3σ), the relative standard deviation (RSD) for 1000 ng/mL etamsylate (n= 7) is 0.96%. The immobilized Ru(bpy)2+ 3 carbon paste electrode shows good electrochemical and photochemical stability. This method is rapid, simple, sensitive and has good reproducibility. It has been successfully applied to the determination of the studied etamsylate in pharmaceutical preparations with satisfactory results. The possible ECL reaction mechanismhas also been discussed. Copyright © 2013 John Wiley & Sons, Ltd. Source

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