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.