<title>Ultrasensitive NIR fluorescence detection and its application to the analysis of DNA</title>

Abstract

The ability to possess detection sensitivity at the single molecule level is a technically challenging task and will have important applications for the analysis of minute quantities of DNA in applications such as Sanger dideoxy sequencing, restriction maps and scanning confocal microscopy. The ability to detect single visible fluorescent dye molecules in solution has recently been demonstrated. We wish to discuss the first report concerning the detection of single near infrared (NIR) dye molecules in solution using photon burst detection and its application for the analysis of minute quantities of DNA. Near infrared excitation and detection was used to reduce the fluorescent impurity contribution to the background, which temporal and spectral filtering cannot overcome in most cases, allowing sensitive detection in complex biological matrices.