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 immobilized in a polypyrrole matrix by an avidin–biotin molecular recognition process. A biotin labeled pyrrole was the precursor of the electropolymerized polymer. 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 for enzyme entrapment in polymer matrixes. These reactive 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 catalytic activity of the membranes has been assessed. A turnover number of 900 in 1 min was determined for the POD membrane. The loss of activity of the enzyme during the membrane formation (42%) by the avidin–biotin method of immobilization was weak. Moreover the enzymatic POD membrane was remarkably stable after a 80-day storage (less than 6% decrease of activity). These performances point to the interest of such enzymatic membranes for the treatment of aqueous media.