A dual-locked fluorescent probe for imaging of human primary melanocytes and melanoma tissues via tyrosinase and hydrogen sulfide activation.

Tyrosinase (TYR) and hydrogen sulfide (H₂S) are two notable biomarkers implicated in melanocyte physiology and melanoma progression. However, no fluorescent probe has been developed for their simultaneous detection in biological systems. Here, we present a dual-locked fluorescein-based probe TyNitro-1 capable of concurrently sensing TYR and H₂S, which incorporates a 3-hydroxyphenyl group for TYR recognition and a nitro moiety for H₂S recognition. Upon dual-analyte activation, the probe displays an obvious fluorescence enhancement at 517 nm. It offers an efficient response (≤120 min for TYR; ≤60 min for H₂S), excellent selectivity, and low detection limits (1.41 U/mL-1 for TYR and 0.28 μM for H2S). In human primary melanocytes, TyNitro-1 reliably monitored changes of TYR and H₂S. While in human melanoma tissues, cryosections incubated with TyNitro-1 exhibited tumor-selective fluorescence that correlated strongly with SOX10 and HMB45 immunostaining. Collectively, this work establishes TyNitro-1 as a proof-of-concept dual-locked fluorescent probe, providing new opportunities to investigate the role of TYR and H₂S in melanocyte biology and highlighting its potential for melanoma diagnosis and intraoperative margin assessment.