A membrane based reactor with an enzyme immobilized by an avidin-biotin molecular recognition in a polymer matrix

Glucose oxidase (GOD) and peroxidase (POD) have successfully been immobiliz ed in a polypyrrole matrix by an avidin-biotin molecular recognition proces s. A biotin labeled pyrrole was the precursor of the electropolymerized pol ymer. The amount of enzyme entrapped in the polymeric matrix was 60% of the initial amount for GOD and 83% for POD; these values are higher than those previously reported fur enzyme entrapment in polymer matrixes. These react ive membranes performed a chemical transformation during the permeation of the substrates; the GOD membrane catalyzed the oxidation of glucose in the presence of oxygen, whereas the peroxidase membrane catalyzed the reduction of hydrogen peroxide in the presence of the oxidant pyrrogallol. The catal ytic activity of the membranes has been assessed. A turnover number of 900 in 1 min was determined fur the POD membrane. The loss of activity of the e nzyme during the membrane formation (42%) by the avidin-biotin method of im mobilization was weak. Moreover the enzymatic POD membrane was remarkably s table after a 80-day storage (less than 6% decrease of activity). These per formances point to the interest of such enzymatic membranes for the treatme nt of aqueous media. (C) 2000 Elsevier Science B.V. All rights reserved.