Recent Advances in Activatable Organic Photoacoustic Probes for In Vivo pH‐ Detection

All life forms require pH homeostasis. The disorder of pH homeostasis is associated with many severe diseases, suggesting the significance of pH‐detection for theranostic diseases. Photoacoustic imaging (PAI) technology has piqued great research interests in spatiotemporal detection of pH in vivo due to its non‐invasiveness and non‐ionization, as well as the high resolution and deep tissue penetration. This mini‐review outlines the most recent advances in activatable organic PA probes for pH‐detection with respect to molecular design, response mechanisms, and their in vivo applications. The basic understanding of PA probes is clarified. The pH‐response mechanisms of the PA probes at the molecular level are particularly emphasized to elucidate the structural design strategies. Finally, the challenges and perspectives, mainly focusing on quantitative detection, are discussed. This review aims to pave the way for further exploration of responsive organic PA probes for in vivo pH‐detection.