The potential of immobilized enzyme membranes in biosensors has been explored in our group for several years. Although part of our work has been mainly devoted t o electrochemical transducers and oxidases for the design of enzyme electrodes, the demand for ultrasensitive and highly selective sensors led us t o consider the use of luminescent enzyme systems associated t o optical transduction. When considering the need for operational and reliable biosensors in biotechnology, immobilization and stability of the sensing element still remain, in most cases, an unavoidable problem. We recently proposed a very fast and reliable procedure for preparing enzymatic membranes from Pall (Biodyne lmmunoaffinity membranes) supplied in a pre-activated form. Both the firefly and bacterial systems as well as peroxidase for the chemiluminescent determination of various analytes, could be bound t o such a support.
Based on this approach, a fibre-optic sensor with immobilized enzymes has been designed which permits bio-or chemiluminescent analysis of ATP, NADH or H202 respectively. With the NADH-based system, other analytes could be detected using coupled dehydrogenases. This device appears very promising and includes the convenience of both the luminescence sensitivity as well as the handling of the biosensor design.