DETECTION OF BOTULINUM TOXIN USING AN EVANESCENT-WAVE IMMUNOSENSOR

Using fluorescein isothiocyanate (FITC)-streptavidin, quartz fibre-imm obilized antibody (F(i)Ab) and the evanescent wave component of a ligh t beam, detection of Botulinum Toxin-B (BoTX) is described. Exposure o f 3-aminopropyltriethoxysilane/ glutaraldehyde (APTS/GA) treated quart z fibres to increasing amounts of anti-BoTX Ab indicated toxin binding to increase in a linear fashion up to approximately 125 ng added Ab. Quantitation of bound BoTX and F(i)Ab by Dot-Blot analysis using avidi n-Horseradish peroxidase (HRP) conjugation indicated the presence of 0 .27 and 0.67 pmoles, respectively. Inclusion of nonbiotinylated BoTX i n sampling mixtures reduced fluorescence in a dose-dependent manner ov er a narrow concentration range (0-300 ng). Exposure of F(i)Ab to a va riety of venoms resulted in no reduction of BoTX binding suggesting de tection of BoTX via immobilized anti-BoTX Ab to be very specific.