Application of an Asymmetric Membrane to an Enzyme Electrode and its Evaluation by Biological Fluid

Abstract

The new immobilized enzyme membrane for a glucose sensor has been developed and evaluated by biological fluids. Glucose oxidase (GOD) was immobilized in the cellulose acetate asymmetric membrane which consists of a- thin and dense skin layer and a porous sponge-layer. The GOD was impregnated in the holes of the skin-layer and cross-linked by glutaraldehyde.
The glucose sensor was constructed using this GOD membrane and a polarographical H₂ O₂ electrode. The response of this sensor to 5×10^-3 M glucose is only 15s. It shows that this membrane has good diffusionability and permeability.
The sensor fitted with a flow through cell was assembled in a flow analysis system. The linear curve in glucose concentration was obtained in the 0-1,000 mg/dl range when flow rate was 2 ml/min and sample size was 5μl, and only 15s. was required to assay one sample.
The sensor was also evaluated by biological fluids. It was used continually at 37° for a month with almost 3,500 assays of serum. The coefficient of variation was 2.5% in the whole blood assay. Having been compaired the whole blood assay value by the glucose sensor with serum assay value by the colorimetry correlation between methods was 0.991.
These results suggest that the new enzyme membrane is expected for practical use.