Employment of an Asymmetric Porous Poly(tetrafluoroethylene) Membrane for Construction of an Ammonia-Electrode-Based Enzyme Electrode

Abstract

A novel asymmetric porous poly(tetrafluoroethylene) membrane (pore size 0.3 2m, thickness 70 m) possessing a hydrophilic (thickness 30 µm) and hydrophobic (thickness 40 /xm) strata! structure was employed to construct an ammonia-electrode-based adenosine electrode. Adenosine deaminase was immobilized in the micropores of the hydrophilic part of the membrane, thus leading to protection of the mechanically weak enzyme layer by the robust poly(tetrafluoroethylene) matrix. The hydrophobic part of the membrane acted as a gas-permeable membrane. Therefore, an adenosine electrode could be constructed by using only a single membrane and a pH electrode. Advantages of employing the enzyme-immobilized asymmetric membrane are: simpler procedures of electrode construction and fast response time, e.g., the time required to attain steady E.M.F. was 2min. at 103 mol/l adenosine at pH=8.5 and at 25°C, while that for a conventional electrode using two separate membrane was 27 min [I. Deng, et al. Anal. Chem., 52,1937 (1980)]. © 1984, The Society of Polymer Science, Japan. All rights reserved.