A robust ratiometric photoacoustic and fluorescence dual-modal molecular probe for capturing endogenous HNO generation in tumor mice model

HNO is reported in association with a wide variety of physiological and pathological states. However, photoacoustic (PA)/fluorescence (FL) dual-modal probes with complementary advantages for detection of HNO in living systems, especially in tumors, are still lacking. Herein, the first near-infrared (NIR) ratiometric PA/FL dual-modal probe (DOP-HNO), composed of a dual ratiometric molecular skeleton caged with 2-(diphenylphosphino)-benzoate group, was designed and synthesized for capturing endogenous HNO generation in vivo. DOP-HNO was able to specifically and sensitively respond to HNO with 4-fold ratiometric fluorescence enhancement (F783/F720) and 2.6-fold ratiometric PA enhancement (PA740/PA670). Moreover, DOP-HNO successfully visualized HNO fluctuations in 4T1 cells and living mice, and the crosstalk between NO and H2S in the tumors of living mice was clearly observed through NIR dual-ratiometric PA/FL imaging, indicating the accurate detection of HNO in vivo. More importantly, using DOP-HNO, for the first time, we provided the visualization evidence of endogenous HNO generation in cancer model and further investigated its possible generation mechanisms by H2S/NO interaction. Thus, we envision that the dual-modal probe DOP-HNO will be an effective tool to study the complex relationship between HNO and cancer as well as the pathology of other HNO-related diseases.