DETECTION OF BOTULINUM TOXIN USING AN EVANESCENT-WAVE IMMUNOSENSOR

Using fluorescein isothiocyanate (FITC)-streptavidin, quartz fibre-immobilized antibody (F(i)Ab) and the evanescent wave component of a light beam, detection of Botulinum Toxin-B (BoTX) is described. Exposure of 3-aminopropyltriethoxysilane/ glutaraldehyde (APTS/GA) treated quartz 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 avidin-Horseradish peroxidase (HRP) conjugation indicated the presence of 0.27 and 0.67 pmoles, respectively. Inclusion of nonbiotinylated BoTX in sampling mixtures reduced fluorescence in a dose-dependent manner over a narrow concentration range (0-300 ng). Exposure of F(i)Ab to a variety of venoms resulted in no reduction of BoTX binding suggesting detection of BoTX via immobilized anti-BoTX Ab to be very specific.