Activatable organic photoacoustic probes for in vivo anion imaging

The merits of non-invasiveness, non-ionization and impressive tissue penetration depth of photoacoustic (PA) imaging technology make it attractive for in vivo detection. Analyte-responsive organic PA probe-based in vivo imaging of bio-functional small anions shows advances in real-time visualization of biological action, early diagnosis and precision therapy of diseases, due to the significance of such anion species in various physiological and pathological processes. In this mini review, the anion-recognition mechanisms of PA probes are particularly focused, from the perspective of chemistry, to exemplify the structural design strategies of activatable organic PA probes. Finally, the challenges and outlooks are discussed to pave the way for further development of PA probes for in vivo imaging of bio-functional small anions, which provides an alternative approach to interpret anion-mediated biological events.