Glucose oxidase (GOX) is immobilized by two different polymer matrices (polyurethane (PU) film and foam) in supercritical carbon dioxide (scCO(2)) environment for an envisioned application in biosensor preparations. Effects of immobilization temperature (25-50 degrees C), pressure (0.1-15 MPa) and immobilization time (4-72 h) on the GOX activity of immobilized PU samples are studied. The interactions between PU and CO2 are also experimentally investigated. Maximum surface area enlargements during foaming between 12 and 250% of the original for PU films and almost no swelling/foaming (0.3-4.4% of original) are observed for PU foams. The swelling/foaming characteristics of PU films are positively correlated with the observed pressure effect on GOX immobilized sample activities. Immobilized sample activities are found to be inversely proportional to the immobilization temperature. Activities obtained for samples prepared at 8, 15 and especially at 10 MPa are 52, 74 and 165%, respectively, greater than the highest value obtained for samples immobilized without using the supercritical CO2 process. (C) 2007 Elsevier Ltd. All rights reserved.