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.