Evaluation of nitroreductase activity in nasopharyngeal carcinoma progression by an activatable two-photon fluorescent probe.

Nasopharyngeal carcinoma (NPC) originating from the epithelium cells is the most common malignant tumor of the head and neck. Small-molecule fluorescent probes for early diagnosis of NPC can effectively improve the 5-year survival rate of patients, which makes it become a research hotspot in recent years. Previous studies have suggested the expression levels of NTR in hypoxic tissues or cells and tumors increased relative to the normal state and were positively correlated with the degree of hypoxia. Regarding the mentioned above, we designed a two-photon fluorescent probe NaT-NTR for the detection of NTR in nasopharyngeal cell lines and tissues at different hypoxia levels. NaT-NTR showed high selectivity and sensitivity toward NTR in a complex physiological environment. Furthermore, imaging NTR in different cell lines revealed that the level of intracellular NTR might be positively correlated with the malignancy of nasopharyngeal carcinoma. More importantly, NaT-NTR was successfully applied to detect and image NTR in human nasopharyngeal carcinoma with a penetration depth of 100 µm. On this basis, NaT-NTR might be a powerful chemical tool for the early diagnosis of nasopharyngeal carcinoma.