(624g) Development of Spr Sensor Receptor Binding Assay to Detect Paralytic Shellfish Poisoning Toxins

Paralytic shellfish poisoning (PSP) is a potentially deadly illness caused by the numerous derivatives of saxitoxin (STX) and tetrodotoxin (TTX), each having different potencies. Traditionally the AOAC mouse bioassay is used to detect the toxicity of a sample which is determined by PSP toxin composition. However, recently a receptor binding assay using radiolabeled STX was developed which uses the mechanism of toxicity, binding of toxins to Na+ gated ion channels of synaptosomes, to assess the toxicity of a sample. The difficultly of safely using radioactive labeled compounds warrants the development of a receptor binding assay with a SPR sensor to detect paralytic shellfish poisoning toxins. In this study, a competitive assay using TTX-streptavidin conjugates, instead of radiolabeled STX, was demonstrated to detect various concentrations of STX, TTX , and mixtures of STX and TTX by binding to a synaptosome surface on a self assembled monolayer (SAM) of alkanethiols. The results for TTX detection were compared to a competitive immunoassay with the SPR sensor by immobilizing TTX antibodies to a SAM surface.