Rapid antibody biosensor assays for environmental analysis

Traditionally, biosensor development has focused on molecules with a define d metabolic role that can be exploited by enzyme-based systems. Antibodies have the ability to move beyond this range of analytes, and are particularl y useful in detecting small, hapten molecules. Electrochemically based bios ensor developments have been less fruitful in this regard, as enzyme labell ing is required, and such assays require the separation from bound and unbo und species. These separations and the removal of background signals result in the increased complexity of the assay format, making it unsuitable for rapid sensor analysis. We have developed an electrochemical sensor based on anti-bodies that does not require the separation of bound and unbound mole cules in a competition immunoassay format. This removes the need for severa l washing and separation steps as is normally employed in this type of assa y. This allows single-step immunoassays to be performed using this system, and also allows for the real-time monitoring of antibody-antigen interactio ns. We have shown that such assays are possible in both batch and flow-inje ction formats and we are currently developing an assay for the pesticide at razine. Tentative results show that analysis with this system is possible i n the p.p.m. to p.p.b. range.