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 γ-hexachlorocyclohexane, and does not detect ( p, p '-dichlorodiphenyl)trichloroethane (DDT).