Development of antibody-based fiber-optic sensors for detection of a benzo[a]pyrene metabolite.

This paper describes the development of an antibody-based fiber-optic sensor designed to detect benzo[a]pyrene (BP) metabolites, in this case r-7,t-8,9,c-10-tetrahydroxy-7,8,9,10-tetrahydrobenzo[a]pyrene (benzopyrenetetraol or BPT), a naturally fluorescent hydrolysis product of DNA adducts that forms during BP metabolism. The sensor's principle of operation is based on diffusion of BPT Into the fiber's reagent phase where it complexes with monoclonal antl-BPT antibody. Reagent phase is immobilized Inside a reusable sensing tip. It consists of either membrane-entrapped liquid antibody or antibody Immobilized on 7-μm silica beads. The antibody binds and concentrates BPT in the fiber's viewing region until equilibrium with the sample is achieved. Typical measurements are performed in 15 min under nonequilibrium conditions. The 325-nm line of a He:Cd laser provides excitation of the immune complex. The Intensity of the resulting fluorescence emission is directly proportional to the amount of BPT in the sample. Sensor response rate varies with BPT concentration in the sample and, under certain circumstances, with antibody concentration in the sensor. At high antibody concentrations, sensor response rate is linear for about 2 h. For 15-min incubations, typical limits of detection are 5 X 10-10M. Significant chemical selectivity is also demonstrated despite the presence of structurally and spectrally similar polynuclear aromatic (PNA) interferents. These results indicate that the fluorolmmunosensor (FIS) is capable of performing highly sensitive and selective immunoassays and could be useful as a screening instrument for BP metabolites in biological samples. Furthermore, the Information provided by this work should be generally applicable to the development of devices for chemically similar systems. © 1988, American Chemical Society. All rights reserved