Polymerization-Amplified Photoacoustic Signal by Enhancing Near-Infrared Light-Harvesting Capacity and Thermal-to-Acoustic Conversion

As a frontier imaging technique for biomedical applications, photoacoustic (PA) imaging has been developed rapidly. The development of new design strategies and excellent PA imaging reagents to boost PA conversion is eagerly desirable for high quality PA imaging but complicated to realize. Herein, we develop a new strategy in which PA imaging reagents with better properties can be easily optimized by polymerization. A series of new PA imaging reagents were designed and synthesized. The polymerization strategy can effectively promote the PA signal by specifically increasing the thermal-to-acoustic conversion efficiency. As these materials shared the same building units, the optimized effectiveness of polymerization strategy in terms of near-infrared light-harvesting capacity and thermal-to-acoustic conversion efficiency are discussed, rationally. The polymers with intense intramolecular motion exhibit an amplified PA signal by elevating thermal-to-acoustic conversion and its higher light-harvesting capability at redshifted region. The simultaneously strong PA signal and photothermal conversion efficiency of p-TTmB NPs enable precise PA imaging and effective photothermal therapy. This work highlights a simple and available design guideline of polymerization for amplifying the PA effect and optimizing existing materials.