An Activated Structure Transformable Ratiometric Photoacoustic Nanoprobe for Real-Time Dynamic Monitoring of HS .

HS has emerged as a promising biomarker for many diseases such as colon cancer and metformin-induced hepatotoxicity. Real-time monitoring of HS levels 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 HS based on the endogenous HS-triggered local surface plasmon resonance (LSPR) red-shift. The Au NRs@Ag nanoprobe can be readily converted into Au NRs@AgS via the endogenous HS-activated sulfurative reaction, subsequently leading to a significant red-shift of the LSPR wavelength from 808 to 980 nm and enabling accurate ratiometric PA (PA/PA) imaging of HS. 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 monitoring of HS-related diseases.