Characterization of antibodies against benzo[a]pyrene with thermodynamic and kinetic constants

Antibodies of a polyclonal antiserum against benzo[a]pyrene were characterized by determining thermodynamic and kinetic constants of the antigen-antibody reaction. Label-free binding assays with optical detection based on reflectometric interference spectroscopy were performed to determine these constants. Different evaluation methods for kinetic measurements were compared. Also, cross-reactivity against two other polycyclic aromatic hydrocarbons, chrysene and pyrene, was checked. The affinity constant between the antibodies and benzo[a]pyrene in homogeneous phase was determined to be K = (5.3 +/- 0.3) x 10(7) M-1 which was in the middle of the usual range of antibody affinities. The association rate constant for the reaction at the surface was determined to be (3.8 +/- 0.9) x 10(5) M-1 s(-1), the dissociation rate constant as (9.7 +/- 0.5) x 10(-3) s(-1). Different evaluation methods applied to the kinetic measurements led to the same results. This antiserum would be suitable for the selective determination of benzo[a]pyrene in concentrated samples. (C) 2002 Elsevier Science B.V. All rights reserved.