title: A SPR-based immunosensor for the detection of isoproturon.
abstract: The proof of principle of a reusable surface plasmon resonance (SPR)-based immunosensor for the monitoring of isoproturon (IPU), a selective and systemic herbicide, is presented. The detecting rat monoclonal anti-isoproturon antibody (mAb IOC 7E1) was reversibly immobilized through the use of a capture mouse anti-rat (kappa-chain) monoclonal antibody (mAb TIB 172), which was covalently immobilized on the sensor chip surface. Such strategy features a controlled binding of the captured detecting antibody as well as facilitates the surface regeneration. The capture of the anti-IPU mAb by the antibody (TIB 172) coated sensor surface could be carried out up to 120 times (immobilization/regeneration cycles) without any evidence of activity loss. With a high test midpoint and a low associated SPR signal, the direct detection format was shown to be unsuitable for the routine analysis of isoproturon. However, the limit of detection (LOD) could be easily enhanced by using a strategy based on a surface competition assay, which improved all immunosensor parameters. Moreover, the sensitivity and working range of the indirect format were found to be dependent on the surface density of the anti-IPU mAb IOC 7E1. As expected for competitive formats, the lowest surface coverage (0.5 ng/mm(2)) allowed a lower detection of the herbicide isoproturon with a calculated LOD of 0.1 microg/l, an IC(50) (50% inhibition) of 5.3+/-0.6 microg/l, and a working range (20-80% inhibition) of 1.3-16.3 microg/l.
authors.affiliation: Institute of Ecological Chemistry, Helmholtz Center Munich, German Research Center for Environmental Health (GmbH), Neuherberg, Germany.
authors.forename: Marie-Françoise
authors.initials: MF
authors.lastname: Gouzy
authors.forename: Melanie
authors.initials: M
authors.lastname: Kess
authors.forename: Petra M
authors.initials: PM
authors.lastname: Krämer
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D017076:Computer-Aided Design; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D010671:Phenylurea Compounds / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D020349:Surface Plasmon Resonance / Q000295:instrumentation*
chemical_list: D004785:Environmental Pollutants; D010671:Phenylurea Compounds; C028904:isoproturon