title: Optical waveguide light-mode spectroscopy immunosensors for environmental monitoring.
abstract: Coupling the high specificity of the immunoanalytical reaction with the high sensitivity of optical waveguide light-mode spectroscopy (OWLS) detection gives the possibility to develop immunosensors with in most cases a definitely lower detection limit than traditionally used immunoassays. Measurements were performed on the sensitized surface of optical waveguide grating coupler sensors (2400 lines/mm grating). The OWLS technique is based on the precise measurement of the resonance angle of a polarized laser light (632.8 nm), diffracted by a grating and incoupled into a thin waveguide. The effective refractive index, determined from the resonance incoupling angle detected at high accuracy, allows determination of layer thickness and coverage (or mass) of the adsorbed or bound material with ultrahigh sensitivity. OWLS immunosensors were developed as label-free immunosensors with an amino group modified SiO(2)-TiO(2) sensor surface on which the immunoreactants could be anchored. One of the components of the antibody-antigen complex was chemically bound on the sensor surface, allowing noncompetitive or competitive detection of the analytes. To illustrate that the resulting immunosensors are suitable for the determination of small and large molecular weight analytes, OWLS sensor formats were applied for quantitative detection of a herbicide active ingredient trifluralin, a Fusarium mycotoxin zearalenone, and an egg yolk protein of key importance in endocrine regulation, vitellogenin.
authors.affiliation: Plant Protection Institute, Hungarian Academy of Sciences, POB 102, H-1525 Budapest, Hungary. aszek@nki.hu
authors.forename: András
authors.initials: A
authors.lastname: Székács
authors.forename: Nóra
authors.initials: N
authors.lastname: Adányi
authors.forename: Inna
authors.initials: I
authors.lastname: Székács
authors.forename: Krisztina
authors.initials: K
authors.lastname: Majer-Baranyi
authors.forename: István
authors.initials: I
authors.lastname: Szendro
mesh_terms: D001681:Biological Assay / Q000295:instrumentation; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D004785:Environmental Pollutants / Q000032:analysis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation*; D055096:Optical Devices; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000295:instrumentation*
chemical_list: D004785:Environmental Pollutants