An Activated Structure Transformable Ratiometric Photoacoustic Nanoprobe for Real-Time Dynamic Monitoring of H 2 S In Vivo .

H 2 S has emerged as a promising biomarker for many diseases such as colon cancer and metformin-induced hepatotoxicity. Real-time monitoring of H 2 S levels in vivo is significant for early accurate diagnosis of these diseases. Herein, a new accurate and reliable nanoprobe (Au NRs@Ag) was designed for real-time dynamic ratiometric photoacoustic (PA) imaging of H 2 S in vivo based on the endogenous H 2 S-triggered local surface plasmon resonance (LSPR) red-shift. The Au NRs@Ag nanoprobe can be readily converted into Au NRs@Ag 2 S via the endogenous H 2 S-activated in situ sulfurative reaction, subsequently leading to a significant red-shift of the LSPR wavelength from 808 to 980 nm and enabling accurate ratiometric PA (PA 980 /PA 808 ) imaging of H 2 S. Moreover, dynamic ratiometric PA imaging of metformin-induced hepatotoxicity was also successfully achieved by the designed PA imaging strategy. These findings provide the possibility of designing a new ratiometric PA imaging strategy for dynamic in situ monitoring of H 2 S-related diseases.