Bench-top antigen detection technique that utilizes nanofiltration and fluorescent dyes which emit and absorb light in the near infrared

This article discusses the development of a bench-top technique to detect antigens in fluids. The technique involves the use of near infrared (NIR) fluorescent dyes conjugated to antibodies, centrifugation, nanofilters, and spectrometry. The system used to detect the antigens utilizes a spectrometer, fiber optic cables, NIR laser, and laptop computer thus making it portable and ideally suited for desk top analysis. Using IgM as an antigen and the secondary antibody, anti-IgM conjugated to the near infrared dye, IRDye™ 800, for detection, we show that nanofiltration can efficiently and specifically separate antibody-antigen complexes in solution and that the complexes can be detected by a spectrometer and software using NIR laser excitation at 778 nm and NIR dye offset emission at 804 nm. The peak power detected at 778 nm for the excitation emission and at 804 nm for the offset emission is 879 pW (−60.06 dBm) and 35.7 pW (−74.5 dBm), respectively.