Objective To prepare supramolecular photosensitizer that can be retained at the site of tumors and that has high light conversion efficiency so as to improve the efficacy of tumor photodynamic therapy (PDT).
Methods A covalent organic framework material based on amino tetraphenyl porphyrin (Tapp), henceforth referred to as Tapp-COF, was synthesized. The spectral characteristics, energy gap characteristics and singlet oxygen generation ability of the material were characterized. Then, Tapp-COF was processed by thin film hydration method to derive T-C@PP, a nano micelle unstable in physiological environment. The same method was used to process Tapp in order to make T@PP micelles, which were used as the controls. The particle size, potential, surface morphology and stability were examined. B16F10 mouse melanoma cells were injected subcutaneously into C57 mice and T-C@PP or T@PP were injected intratumorally, followed by light exposure or no light exposure. We assessed the in vitro photodynamic killing efficiency of the nano micelles and the status of tumor cells co-cultured with the photosensitizer micelles and validated the tumor retention ability and killing efficiency of the micelles.
Results Compared with Tapp, Tapp-COF displayed higher photodynamic conversion efficiency, and could produce more ROS. The T-C@PP micelles were unstable in physiological environment, and adsorptive aggregation would occur after co-culturing with tumor cells for a period of time. T-C@PP showed low cytotoxicity when there was no light exposure, but could kill tumor cells at relatively low concentration under 660 nm laser irradiation. T-C@PP could be retained in tumor tissue, and had better in vivo killing efficiency that that of T@PP.
Conclusion In this study, highly efficient TPP-COF based T-C@PP micelles were prepared. Under physiological conditions, these micelles could achieve tumor retention through self-aggregation. Possessing sound safety, the nano micelles showed promise for potential application in tumor PDT.
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