The application discloses a ratio type near-
infrared fluorescent probe based on an ICT-FRET mechanism and a preparation method and application thereof. The ratio type near-
infrared fluorescent probe based on the ICT-FRET mechanism emits in a near-
infrared region, has an ultra-large
stokes shift, can effectively avoid excitation light interference and self-absorption, reduces biological
background fluorescence, and is suitable for
deep tissue imaging. The probe can realize double-emission ratio response (I 660 / I 540 ) based on the FRET mechanism, has a significant
signal change, has inherent self-calibration capability, shows extremely
high selectivity to Cys, has almost no response to Hcy and GSH similar in structure, is strong in anti-environmental interference, and is more accurate in quantification. The TPP targeting group of the probe enables the probe to be specifically positioned in mitochondria of living cells, realizes dynamic ratio imaging of endogenous and exogenous Cys in mitochondria, and provides a powerful tool for studying Cys
metabolism at a subcellular level.