A novel lysosome-targeted NIR emitting two-photon fluorescent probe and its application in H2S detection

Two-photon fluorescent probes offer key advantages for biological imaging, including deep tissue penetration, minimal photobleaching and photodamage, and low background interference. However, the emission wavelength of most two-photon fluorescent probes is within the blue-green region, which limits these advantages. Moreover, the few reported NIR two-photon fluorescent probes suffer from drawbacks such as low quantum yield, small two-photon cross section, and poor water solubility. To address these issues, we constructed a new two-photon fluorophore, NADCO, by combining naphthalimide and dicyanoisophorone. NADCO exhibits remarkable optical properties, including two-photon excitation wavelength of 900 nm, NIR emission wavelength of 706 nm, large two-photon cross section of 303 GM, and high quantum yield of 26.61 %. Considering the critical signaling role of H2S in living organisms, we further exploited this fluorophore to synthesize an H2S fluorescent probe NADCO-DBS. NADCO-DBS shows high sensitivity and selectivity for H2S with a detection limit of 12.3 nM. Additionally, NADCO-DBS demonstrates remarkable lysosomal targeting ability in cell imaging with a Pearson coefficient up to 0.94. This work provides a promising tool for exploring the physiological and pathological roles of H2S and lysosomes, and furnishes a novel approach for the development of highperformance NIR two-photon fluorescent probes.