RAPTOR: a fluoroimmunoassay-based fiber optic sensor for detection of biological threats

The RAPTOR was developed to meet the need for a small, portable, easily operated biosensor for the detection of biological threats in the field. This device has evolved over a number of years to reach its current level of maturity. This paper describes details of the RAPTOR's design, including the recent upgrades to the fluidics and optics subsystems, as well as design improvements that have increased both system reliability and sensitivity. Working with these system upgrades, we also investigated biochemical methods that further improve assay sensitivity. The use of NeutrAvidin/biotin chemistry to improve immobilization of the capture antibody, coupled with use of the fluorophore Alexa Fluor 647 to label the tracer antibody, has resulted in a two- to four-fold signal enhancement. These gains, in combination with redesigned optics and instrumentation, have resulted in approximately a log-order improvement over earlier systems. These improvements are shown for an assortment of analytes of interest, including Staphylococcal enterotoxin type-B, Francisella tularensis, Bacillus anthracis, and Bacillus globigii spores.