Fiber optic biosensor for cyclodiene insecticides

Chlorendic caproic acid (CCA) was used to synthesize hexachlorocyclopentadienefluorescein (FL) and bovine serum albumin (BSA) conjugates. Anti-CCA antibodies (CCA-Abs), which were raised against BSA-CCA and immobilized on quartz fibers, bound FL-CCA selectively and reversibly. Fluorescence generated by evanescent excitation of the bound FL-CCA was used to monitor the binding event. The affinity of CCA-Abs for FL-CCA (K-D = 1.9 nM) was calculated from the time courses of association and dissociation of FL-CCA. The cyclodiene insecticides chlordane, heptachlor, dieldrin, endrin, aldrin, and endosulfan competed with FL-CCA for binding to CCA-Abs and reduced fluorescence in a concentration-dependent manner with the following rank order: chlordane > heptachlor > dieldrin > aldrin > endosulfan. This fiber optic fluoroimmunosensor detects cyclodiene insecticides at the ppb level, has low cross-reactivity with gamma-hexachlorocyclohexane, and does not detect (p,p'-dichlorodiphenyl)trichloroethane (DDT).