A TPP-OH-based near-infrared fluorescent nanoprobe for cellular and in vivo H₂S detection and imaging

The physiological and pathological processes of many diseases are influenced by hydrogen sulfide (H₂S), a physiologically active gaseous signaling molecule. Near-infrared fluorescent (NIR) probes are valued for their high specificity, sensitivity, simplicity, and safety. A near-infrared fluorescent probe (TPNPs), sensitive to H₂S, was designed and synthesized from 4-(10,15,20-triphenylporphyrin-5-yl)phenol (TPP-OH). Due to the creation of hydroxyl groups from ether thiolation, it was discovered that Na₂S treatment of TPNPs with Na₂S as the H₂S donor produced a large "turn-on" near-infrared fluorescence response. Additionally, the fluorescence intensity of TPNPs at 650 nm was significantly enhanced with the increase of Na₂S content. The fluorescence intensity of TPNPs at 650 nm showed a strong linear relationship with Na₂S concentration within the concentration range of 0-50 μM, with a detection limit of 0.88 μM. Furthermore, TPNPs were effectively used to investigate exogenous and endogenous H₂S in mice and live cells.