ENVIRONMENTAL IMMUNOASSAY FOR THE EXPLOSIVE RDX USING A FLUORESCENT DYE-LABELED ANTIGEN AND THE CONTINUOUS-FLOW IMMUNOSENSOR

To assist in explosives detection for airport security and environment al remediation efforts, a biosensor has been developed at the Naval Re search Laboratory based on immunoassays for explosives which are inexp ensive, sensitive, and specific for the compound in question. Recently , an analog and antigen-protein complex of the plastic explosive hexah ydro-1,3,5-trinitro-1,3,5-triazine (RDX) became commercially available . In this report, we present a synthetic scheme for the preparation of a dye-labeled analog of RDX and demonstrate its use in the detection of explosives in environmental samples. The RDX analog is linked to th e succinimidyl ester of a sulfoindocyanine dye via two amide bonds usi ng 1,5-diaminopentane. This dye conjugate is then allowed to bind to a ntibodies against RDX which are immobilized on plastic beads inside a 100 mu l column. Upon injection of samples into the stream of buffer f lowing through the column, the fluorescent analog is displaced from th e column in amounts which are proportional to the concentration of the analyte. Concentrations of RDX as low as 15 ppb are easily measurable in laboratory samples using this system. The continuous-flow immunose nsor is also able to detect quantitatively RDX in environmental sample s.