Single Side‐Chain‐Modulatory of Hemicyanine for Optimized Fluorescence and Photoacoustic Dual‐Modality Imaging of H₂S In Vivo

Near‐infrared fluorescence (NIRF)/photoacoustic (PA) dual‐modality imaging integrated high‐sensitivity fluorescence imaging with deep‐penetration PA imaging has been recognized as a reliable tool for disease detection and diagnosis. However, it remains an immense challenge for a molecule probe to achieve the optimal NIRF and PA imaging by adjusting the energy allocation between radiative transition and nonradiative transition. Herein, a simple but effective strategy is reported to engineer a NIRF/PA dual‐modality probe (Cl‐HDN 3 ) based on the near‐infrared hemicyanine scaffold to optimize the energy allocation between radiative and nonradiative transition. Upon activation by H 2 S, the Cl‐HDN 3 shows a 3.6‐fold enhancement in the PA signal and a 4.3‐fold enhancement in the fluorescence signal. To achieve the sensitive and selective detection of H 2 S in vivo, the Cl‐HDN 3 is encapsulated within an amphiphilic lipid (DSPE‐PEG 2000 ) to form the Cl‐HDN 3 ‐LP, which can successfully map the changes of H 2 S in a tumor‐bearing mouse model with the NIRF/PA dual‐modality imaging. This work presents a promising strategy for optimizing fluorescence and PA effects in a molecule probe, which may be extended to the NIRF/PA dual‐modality imaging of other disease‐relevant biomarkers.