Degradable Semiconducting Oligomer Amphiphile for Ratiometric Photoacoustic Imaging of Hypochlorite.

Upregulation of highly reactive oxygen species (ROS) such as hypochlorite (ClO- ) is associated with many pathological conditions including cardiovascular diseases, neuron degeneration, lung injury, and cancer. However, real-time imaging of ClO- is limited to the probes generally relying on fluorescence with shallow tissue-penetration depth. We here propose a self-assembly approach to develop activatable and degradable photoacoustic (PA) nanoprobes for in vivo imaging of ClO- . A near-infrared absorbing amphiphilic oligomer is synthesized to undergo degradation in the presence of a specific ROS (ClO- ), which integrates a π-conjugated but ClO- oxidizable backbone with hydrophilic PEG side chains. This molecular architecture allows the oligomer to serve as a degradable nanocarrier to encapsulate the ROS-inert dye and self-assemble into structurally stable nanoparticles through both π-π stacking and hydrophobic interactions. The self-assembled nanoprobe exhibits sensitive and specific ratiometric PA signals toward ClO- , permitting ratiometric PA imaging of ClO- in the tumor of living mice.