Near-infrared laser-induced fluorescence detection in capillary electrophoresis

As capillary electrophoresis continues to focus on miniaturization, either through reducing column dimensions or situating entire electrophoresis syst ems on planar chips, advances in detection become necessary to meet the cha llenges posed by these electrophoresis platforms. The challenges result fro m the fact that miniaturization requires smaller load volumes, demanding hi ghly sensitive detection. In addition, many times multiple targets must be analyzed simultaneously (multiplexed applications), further complicating de tection. Near-infrared (NIR) fluorescence offers an attractive alternative to visible fluorescence for critical applications in capillary electrophore sis due to the impressive limits of detection that can be generated, in par t resulting from the low background levels that are observed in the NIR. Ad vances in instrumentation and fluorogenic labels appropriate for NIR monito ring have led to a growing number of examples of the use of NIR fluorescenc e in capillary electrophoresis. In this review, we will cover instrumental components used to construct ultrasensitive NIR fluorescence detectors, inc luding light sources and photon transducers. In addition, we will discuss v arious types of labeling dyes appropriate for NIR fluorescence and finally, we will present several applications that have used NIR fluorescence in ca pillary electrophoresis, especially for DNA sequencing and fragment analysi s.