Construction of NIR-II polymeric photosensitizers and their biomedical applications

We designed a novel conjugated polymer (CP) and developed CPN-PEGnk (n = 2 or 5), an integrated nanoplatform through PEGylation. CPN-PEG5k demonstrated significant improvements over physically encapsulated nanoparticles (F127@CPN), including a red-shift in NIR absorption, a 2.97-fold increase in NIR-II fluorescence intensity, and retained excellent ROS generation and photothermal conversion capability. The exceptional NIR-II imaging performance of CPN-PEG5k was validated through blood circulation imaging in mice, achieving a signal-to-background ratio of 8.9. In a breast cancer mouse model, CPN-PEG5k effectively eradicated tumors, stimulated immune responses, and suppressed tumor progression and metastasis. These results highlight CPN-PEG5k's potential in advancing conjugated polymer applications for NIR-II imaging.