Dong-Mung Tsai

Amperometric determination of ascorbic acid at a ferricyanide-doped Tosflex-modified electrode

Abstract Tosflex, a perfluoro-anionic exchange membrane, is not studied as much as Nafion for electroanalytical applications. In this study, electrocatalytic oxidation of ascorbic acid (AA) was demonstrated using a ferricyanide-doped Tosflex-modified electrode in pH 5 phosphate buffer solution. The modified electrode showed good stability over the studied pH range of 2–12. The electrocatalytic oxidation of AA on the modified electrode follows the surface-saturation kinetics in terms of Michaelis-Menten (MM) mechanism. The analytical estimations were performed amperometrically under hydrodynamic conditions at an applied potential of 300 mV versus Ag/AgCl. A linear response was observed in the range of 0–50 μM with a regression coefficient of 0.998.

Fabrication of a Glucose Biosensor Based on Inserted Barrel Plating Gold Electrodes

We demonstrate here the application of barrel plating gold electrodes for fabricating a new type of disposable amperometric glucose biosensor. It is prepared by inserting two barrel plating gold electrodes onto an injection molding plastic base followed by immobilizing with a bioreagent layer and membrane on the electrode surface. The primary function of barrel plating is to provide an economical way to electroplate manufactured parts. The manufacture procedure is simple and can increase the fabrication precision for automation in mass production. At the two-electrode system, the detection of glucose is linear up to 800 mg/dL (i.e., 44.5 mM, r(2) > 0.99) in pH 7.4 PBS with a sensitivity of 0.71 microA/mM. Excellent sensor-to-sensor reproducibility shows coefficients of variation of only 0.8-1.4% for the detection of 56.5-561.0 mg/dL glucose. In laboratory trials 176 capillary blood samples with a range of 30-572 mg/dL glucose are used to evaluate the clinical application of the biosensor. A good linear correlation is observed between the measured values of the proposed biosensor and laboratory reference. Error grid analysis verifies that the proposed technique is promising in fabricating biosensor strips on a mass scale. As successfully demonstrated by using whole blood glucose as a model analyte, the fabrication technique can extend into other barrel plating noble metal electrodes for various applications.