Silk fibroin/cellulose acetate membrane electrodes incorporating xanthine oxidase for the determination of fish freshness Original Research Article

A bilayer coated-wire electrode incorporating xanthine oxidase is reported to estimate fish freshness. The modified electrode is constructed with two membranes, a silk fibroin membrane with immobilized enzyme and a cellulose acetate membrane to eliminate the interference from high molecular weight compounds such as proteins. The biosensor is based on detecting hydrogen peroxide released from the enzymatic reaction. It shows high sensitivity and long-time stability for fish samples. The minimum concentration of hypoxanthine that could be detected was 1×10−7 mol l−1. Due to the protection of the cellulose acetate membrane, the electrode was stable for six weeks or 400 assays of fish tissue samples. The results were in good agreement with those of traditional assays for determination of the freshness of some kinds of river fishes.