A novel near-infrared fluorescent probe for specific imaging of telomerase reverse transcriptase in vivo

Identifying the expression levels of human telomerase reverse transcriptase (hTERT) is important for early cancer diagnosis and cancer-related drug screening. However, a small-molecule fluorescent probe has rarely been used for rapidly determining the hTERT level with high sensitivity has been scarce. Herein, we designed and synthesized a novel near-infrared fluorescent probe (NB-BIBRA) by conjugating an inhibitor analog (BIBRA) to the fluorophore Nile blue (NB) for specific imaging of hTERT in living cells and in vivo. In the absence of hTERT, NB-BIBRA mainly exists in aggregates, exhibiting self-quenching photoactivity. However, once NB-BIBRA interacts with hTERT, NB-BIBRA aggregates are disrupted and their fluorescence intensity is drastically enhanced. Notably, the probe exhibited a low detection limit, high selectivity and rapid response to hTERT, allowing rapid imaging of hTERT in living cells and solid tumor tissue in vivo. To the best of our knowledge, NB-BIBRA is the first near-infrared fluorescent probe for the detection and imaging of hTERT in living cells and in vivo, thus providing a powerful tool for early cancer diagnosis and cancer-related drug screening.