Near-infrared (NIR) fluorescence imaging is a noninvasive technique that provides numerous advantages for the realtime in vivo monitoring of biological information in living subjects without the use of ionizing radiation. Near-infrared fluorescent (NIRF) dyes are widely used as fluorescent imaging probes. | Research progress of near-infrared fuorescence probes based on indole heptamethine cyanine dyes in vivo and in vitro