IMMUNOASSAY OF FUMONISINS BY A SURFACE-PLASMON RESONANCE BIOSENSOR

A surface plasmon resonance (SPR) immunosensor is developed to determi ne concentrations of the mycotoxin, fumonisin B-1 (FB1), in spiked sam ples. Polyclonal antibodies produced against FB1 are adsorbed onto a t hin gold film substrate, which is coupled to a glass prism in the Kret schmann configuration. The output beam of a planar light-emitting diod e is focused through the prism to excite SPR at the surface of the gol d film. When a sample containing FB, is added to a cell on the outside of the gold film, the angular profile of reflected light intensity sh ifts. This changes the resonance angle and the reflected beam intensit y at a selected angle, both of which are proportional to the FB1 conce ntration. After optimization of the antibody overlayer, a detection li mit of 50 ng/mL is obtained for the direct assay with an analysis time under 10 min. Multiple sample additions and large-volume sample circu lation can be used with the high-affinity antibodies to achieve lower detection limits. (C) 1998 Academic Press.