Ratiometric Near-Infrared Fluorescence Liposome Nanoprobe for H(2)S Detection In Vivo

Accurate detection of H(2)S is crucial to understanding the occurrence and development of H(2)S-related diseases. However, the accurate and sensitive detection of H(2)S in vivo still faces great challenges due to the characteristics of H(2)S diffusion and short half-life. Herein, we report a H(2)S-activatable ratiometric near-infrared (NIR) fluorescence liposome nanoprobe HS-CG by the thin-film hydration method. HS-CG shows “always on” fluorescence signal at 816 nm and low fluorescence signal at 728 nm; the NIR fluorescence ratio between 728 and 816 nm (F(728)/F(816)) is low. Upon reaction with H(2)S, the fluorescence at 728 nm could be more rapidly turned on due to strong electrostatic interaction between enriched HS(−) and positively charged 1,2-dihexadecanoyl-sn-glycero-3-phosphocholine (DPPC) doped in the liposome nanoprobe HS-CG, resulting in a large enhancement of F(728)/F(816), which allows for sensitive visualization of the tumor H(2)S levels in vivo. This study demonstrates that this strategy of electrostatic adsorption between HS(−) and positively charged molecules provides a new way to enhance the reaction rate of the probe and H(2)S, thus serving as an effective platform for improving the sensitivity of imaging.