Semiconducting Polymer Nanoparticles for Centimeters‐Deep Photoacoustic Imaging in the Second Near‐Infrared Window

Thienoisoindigo‐based semiconducting polymer with a strong near‐infrared absorbance is synthesized and its water‐dispersed nanoparticles (TSPNs) are investigated as a contrast agent for photoacoustic (PA) imaging in the second near‐infrared (NIR‐II) window (1000–1350 nm). The TSPNs generate a strong PA signal in the NIR‐II optical window, where background signals from endogenous contrast agents, including blood and lipid, are at the local...