Cubic POSS engineering of photosensitizer-doped semiconducting polymer nanoparticles for enhanced fluorescence imaging and amplified photodynamic therapy

Herein, we demonstrate photosensitizer-doped semiconducting polymer nanoparticles (SPNs) with simultaneous enhanced fluorescence brightness and amplified photodynamic performance through the simple introduction of a cubic polyhedral oligomeric silsesquioxane (POSS) structure and alkyl chains. Compared to semiconducting polymer nanoparticles that are doped with THPP (THPP-doped PFO NPs and THPP-doped PFBT NPs), PorPOSSC12-doped SPNs exhibited roughly 7.2 times and 3.2 times higher fluorescence quantum yield for PorPOSSC12-doped PFO NPs and the PorPOSSC12-doped PFBT NPs, respectively. Moreover, the stability of these particles could be improved effectively by the interaction of POSS and the long alkyl chains in the photosensitizer with the polymer backbones of the nanoparticles. In vitro experiments also proved that these PorPOSSC12-doped semiconducting polymer nanoparticles showed bright fluorescence imaging and enhanced photodynamic effects. This strategy is expected to be applicable to a broad range of semiconducting polymers for the development of SPN-based photosensitizer bright fluorescence emission, efficient PDT ability, and improved colloidal stability.