Analytical Sciences

Comparison of Enzymatic Recycling Electrodes for Measuring Aminophenol: Development of a Highly Sensitive Natriuretic Peptide Assay System

Yasuhiro MIE,* Keiko KOWATA,* Yu HIRANO,* Osamu NIWA,** and Fumio MIZUTANI*

*Hokkaido Center, National Institute of Advanced Industrial Science and Technology (AIST), 2-17-2-1 Tsukisamu-higashi, Sapporo 062-8517, Japan
**Tsukuba Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8566, Japan

Several redox enzymes were examined for enzymatic/electrochemical-recycling systems in order to measure p-aminophenol (PAP) with high sensitivity. Glucose oxidase (GOD) and diaphorase (DI) worked well as catalysts for recycling electrode systems: these enzymes effectively reduced p-iminoquinone (PIQ), the electrochemically-oxidized form of PAP, and caused an enhancement in the electrochemical signals (anodic currents in the voltammogram and amperogram) by ∼ 100 fold. The lower detection limits for PAP were estimated to be 50 nM with the GOD system and 2 nM with the DI system. We combined the enzymatic-recycling electrode using DI with an enzyme immunoassay system to measure atrial natriuretic peptide (ANP), an important marker peptide hormone involved in heart diseases. ANPs from serum samples at ppt-levels were determined appropriately using the present assay system.

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