A SURFACE-PLASMON RESONANCE-BASED IMMUNOSENSOR FOR HIGHLY SENSITIVE DETECTION OF MORPHINE

Highly sensitive and selective detection of morphine (MO) based on sur face-plasmon-resonance (SPR) was realized by using an anti-MO monoclon al antibody and MO-bovine serum albumin (MO-BSA) conjugate (antigen). MO-BSA was immobilized on the Au thin film of the SPR sensor chip by p hysical adsorption. The incident angle of the SPR system using the MO- BSA immobilized chip increased almost linearly with increasing concent ration of antibody up to ca. 5 mu g ml(-1) (ppm). The addition of MO t o the antibody solution (5 ppm) was found to reduce the incident angle shift sharply because of the inhibition effect of MO. Based on this i nhibiting principle, the present sensor could detect MO in the concent ration range 0.1-10 ng ml(-1) (ppb). The affinity constants between th e antibody and the antigens (MO and MO-BSA) could be obtained by assum ing a Langmuir adsorption model for the immunoreaction system. (C) 199 8 Elsevier Science S.A. All rights reserved.