A ganglioside-based assay for cholera toxin using an array biosensor

A rapid assay for cholera toxin (CT) has been developed using a fluorescenc e-based biosensor, This sensor was capable of analyzing six samples simulta neously for CT in 20 min with few manipulations required by the operator. T he biochemical assays utilized a ganglioside-"capture" format: ganglioside GM1, utilized for capture of analyte, was immobilized in discrete locations on the surface of the optical waveguide. Binding of CT to immobilized GM1 was demonstrated with direct assays (using fluorescently labeled CT) and "s andwich" immunoassays (using fluorescently labeled tracer antibodies). Limi ts of detection for CT were 200 ng/ml in direct assays and 40 ng/ml and 1 m u g/ml in sandwich-type assays performed using rabbit and goat tracer antib odies. Binding of CT to other glycolipid capture reagents was also observed . While significant CT binding was observed to loci patterned with GD1b, Gb 3, and Gb4, CT did not bind significantly to immobilized GT1b at the concen trations tested. This is the first description of such a non-antibody-based recognition system in a multi-specific planar array sensor. (C) 2000 Acade mic Press.