Development of Semiconducting Polymer Nanoparticles for Photoacoustic Imaging

Semiconducting polymer nanoparticles (SPNs) have evolved into a new class of photonic materials with great potential for biomedical applications. Depending on the polymer structures, SPNs can be developed into optical agents for fluorescence and chemiluminescence imaging, photosensitizers for photodynamic therapy, and heat converters for photothermal therapy. In this feature article, recent work is summarized on the development of SPNs for in vivo photoacoustic (PA) imaging, a state-of-the-art imaging modality that converts light energy into mechanical acoustic waves to provide deep tissue penetration. The structure-property relationship and doping approaches are discussed to reveal the importance of promoting nonradiative decay in amplifying the PA brightness of SPNs. Moreover, their imaging applications, including lymph node mapping, tumor imaging, and monitoring of pathological indexes, are highlighted. These studies demonstrate that SPNs can serve as versatile PA agents for advanced molecular imaging applications.