Incorporation of EDTA for the elimination of metal inhibitory effects in an amperometric biosensor based on mushroom tissue polyphenol oxidase

Enzyme based biosensors are highly selective devices which rely on the spec ific binding of the target analyte (the substrate) to the active-site regio ns of the enzyme. The enzymatic reaction between mushroom tissue polyphenol oxidase and its substrate phenol is coupled with the use of potassium ferr ocyanide (K4Fe(CN)(6)) as the mediator in ammonia buffer solution (pH 8.80) . The response of devices is often affected by the presence of inhibitors, which combine with the free enzyme in a manner that prevents substrate bind ing. The objective of this study is to describe an efficient and yet simple stra tegy to eliminate the interference of metals in amperometric biosensing. Th e methods relies on in situ removal of the interfering metal by a surface-b ound complexing agent, disodium ethylenediaminetetraacetate (EDTA). EDTA is incorporated into the electrode by mixing it within the enzyme-containing carbon paste matrix. Mixed enzyme/carbon paste electrodes are receiving con siderable attention for the preparation of fast responding biosensors.