beta-lactamase label-based potentiometric biosensor for alpha-2 interferondetection

An effective immunosensor for alpha-2 interferon detection based on pH-sens itive field effect,transistor (pH-FET) has been developed. A specific sensi ng element was fabricated by immobilizing alpha-2 interferon on the gate of a pH-FET. The interaction of anti-interferon antibodies labelled with beta -lactamase with interferon-pH-FET (in the presence of specific enzyme subst rate) leads to a local pH-change at the surface of transducer and produces an electrochemical signal which is proportional to the conjugate concentrat ion. The main performance characteristics of the sensor obtained (sensitivi ty, dynamic range, operational and storage stability) were estimated. The e ffect of pH, buffer concentration and ionic strength on the immunosensor re sponse as well as conditions of immunosensor regeneration were studied. For the determination of the interferon concentration in a sample solution the competitive electrochemical immunoassay has been employed. A linear respon se of the sensor on alpha-2 interferon concentration is obtained in the ran ge 10-100 mu g/ml. This gives the possibility to detect alpha-2 interferon in a non-diluted cultivated broth. The data of the competitive electrochemi cal immunoassay are available within 30 min and are in good accordance with the enzyme-linked immunosorbent assays. (C) 1999 Elsevier Science B.V. All rights reserved.