APPLICATION OF A PLASTIC EVANESCENT-WAVE SENSOR TO IMMUNOLOGICAL MEASUREMENTS OF CKMB

The principles of evanescent-wave fluorescent spectroscopy have been a pplied to the development of an immunoassay for creatine kinase (CK, E C 2.7.3.2) isoenzyme MB form (CKMB) with a molecular weight of about 8 4 000 using an injection-molded conical sensor. The sensor element is designed to: (i) provide an active surface area (157 mm(2)) similar to that of fiber-optic sensors; (ii) reduce the requirements for a high numerical launch aperture NA from 0.6 to approximately 0.1 or less; an d (iii) provide a robust element capable of being handled by non-criti cal surfaces for possible commercial applications. The resultant blunt -ended cone is constructed from a substrate of poly(methylmethacrylate ) having a refractive index n(1)(530) = 1.4952 and a propagation surfa ce angled at 23 degrees with respect to the cone axis, The cones are c oated with mouse antibodies against CKMB and used in conjunction with a monoclonal antibody covalently coupled to the fluorescent tracer B-p hycoerythrin.