A near-infrared fluorescent probe for nitroreductase with type I photodynamic effect and drug release capability.

Combining chemotherapy with photodynamic therapy has attracted attention because it often yields better therapeutic effects than single-modality treatments. In this work, we synthesized a prodrug-type nitroreductase fluorescent probe CB. When CB is unreacted, it exhibits almost no fluorescence signal. Upon reaction with NTR, it releases a Type I photosensitizer CB-OH with near-infrared I emission (708 nm), and indomethacin. The probe features a relatively fast response time (36 min), a low detection limit (46.16 ng/mL), and good biocompatibility. The Type I photodynamic effect of the photosensitizer CB-OH allows it to function more effectively in the hypoxic tumor environment. This indicates that probe CB possesses excellent imaging performance and potential for combined photodynamic-chemotherapy.