Π-conjugated polymers based contrast agents for photoacoustic imaging and photothermal therapy

Π-Conjugated polymers have garnered significant attention as potential bioagents for photoacoustic imaging (PAI) and photothermal therapy (PTT) in vivo, owing to their exceptional characteristics, including optical stability, flexibility, high absorbance, and efficient photothermal conversion. Over the past decade, research on semiconducting polymers has mainly concerned with modifying their structure and composition to improve various aspects of their performance, such as photothermal conversion efficiencies (PCEs), hydrophilicity, biocompatibility, and extending their applications. In this review, we first give a brief introduction of the common polymerization units and preparation routes of semiconducting polymers, as well as the strategies used to synthesize polymeric bioagents. Then we classify the polymers based on their electron-acceptor units and summarize the strategies and underlying mechanisms used to enhance their PAI and/or PTT performance. Finally, we review the biomedical applications of these polymeric bioagents based on their PAI and/or PTT performance.