Mitochondria-Targeted Fluorescent and Photoacoustic Imaging of Hydrogen Peroxide in Inflammation

Abstract

Hydrogen peroxide (H₂O₂) is a prominent reactive oxygen species with relative stability, which makes it a potential diagnostic marker for pathological states. Excessive H₂O₂ in mitochondria leads to oxidative stress and inflammation. However, precisely monitoring the level of H₂O₂ at specific organelles (<i>e.g.</i>, mitochondria) <i>in vivo</i> is still of urgent necessity. Therefore, we rationally designed a mitochondria-targeted near-infrared probe <b>TPP-HCy-BOH</b> for fluorescent/photoacoustic (FL/PA) dual-modal imaging of overproduced H₂O₂ in an inflamed mouse model. <b>TPP-HCy-BOH</b> had a low LOD (0.348 μM), which is comparable to those of recently reported probes for H₂O₂ detection. The high kinetic rate constant (<i>k</i>_obs = 4.72 × 10^-3 s^-1) of <b>TPP-HCy-BOH</b> toward H₂O₂ is superior to recently reported H₂O₂ probes. Compared to control probe <b>HCy-BOH</b> without the mitochondrial targeting moiety, <b>TPP-HCy-BOH</b> successfully images exogenous or endogenous H₂O₂ in mitochondria with an additional 2.4-fold FL increase and 4.7-fold PA increase in HeLa cells or additional 2.1-fold FL increase and 3.3-fold PA increase in RAW 264.7 cells. In LPS-induced acute inflammation <i>in vivo</i>, <b>TPP-HCy-BOH</b> is more competent to image overproduced H₂O₂ with additional 1.6-fold higher sensitivity of FL in abdomen and 2.0-fold higher sensitivity of PA in liver and longer retention time of 0.5 h than <b>HCy-BOH</b>. We anticipate that <b>TPP-HCy-BOH</b> could be employed for the FL/PA dual-modal diagnosis of pathological inflammation in clinic in near future.