Eight analyte detection using a four-channel optical biosensor

RAPTOR is a small, portable, and easily operated biosensor capable of performing rapid immunoassays in the field. This fiber optic biosensor is commercially available and is designed to detect up to four different analytes at one time. RAPTOR performs sandwich fluoroimmunoassays on four optical waveguides simultaneously, with assay results from all four fibers available in less than 12 minutes. This paper describes an easy modification that doubles the multi-analyte detection capability of RAPTOR using the same four optical waveguides. Three different sets of capture antibodies were immobilized onto the four waveguides in such a combination that any one of eight analytes was identified in a sample by the pattern of the response. While the overall signal strength was significantly reduced (similar to 2/3) in several assays, the following eight antigens could be clearly detected at the concentrations tested: staphylococcal enterotoxin type-B (SEB), Francisella tularensis LVS, Bacillus anthracis Sterne, ricin, Yersinia pestis F1 antigen, MS2 bacteriophage, cholera toxin, and Salmonella typhimurium. This simple modification of a standard immunoassay method maximizes the functionality of this instrument, while requiring no additional parts or assay steps.