One-step synthesis of cyclodextrin-based fluorescent hyperbranched polymer as type I photosensitizer for effective photodynamic therapy

Photodynamic therapy (PDT) is a promising treatment regime for cancer therapy with some advantages such as minimal invasiveness, high spatiotemporal selectivity, and negligible drug resistance. Developing Type I photosensitizer (PS) is a viable strategy to overcome the limitations of conventional O2-dependent Type Ⅱ PS, whereas there are still significant challenges. Herein, we report the synthesis of β-cyclodextrin-based fluorescent hyperbranched polymer (β-CD-HPG-DEP) through a one-step anionic ring-opening polymerization between β-cyclodextrin (β-CD), glycidol and a fluorescent molecule DEP. The potential utilization of β-CD-HPG-DEP as the agent for cancer phototheranostics was also investigated in detail. The results demonstrated that β-CD-HPG-DEP possesses excellent water dispersibility, good biocompatibility, high reactive oxygen species (ROS) generation efficiency mainly via Type I mechanism, and extraordinary fluorescence imaging capability. Meanwhile, β-CD-HPG-DEP has great potential to serve as drug delivery vehicle since the cyclodextrin unit has many hydroxyl groups, thus providing a promising strategy for designing and fabrication of multifunctional theranostics. Considering the simple synthesis route, ready designability and multifunctional potential of anionic ring-opening polymerization, as well as good biocompatibility of resultant polymer, we believe the strategy developed in this work could also be a rational route to synthesize multifunctional composites for various biomedical applications.