Ratiometric singlet oxygen self-detecting and oxygen self-supplying nanosensor for real-time photodynamic therapy feedback and therapeutic effect enhancement

Abstract

Integration of singlet oxygen (1O2) detection that provides necessary therapeutic feedback into nanotheranostics for hypoxic tumor photodynamic therapy (PDT) is desirable but still challenging. Herein, we report a nanosensor (denominated PAPD) by combining dual-channel ratiometric sensing and oxygen-augmenting strategies, which synergistically realizes real-time 1O2 self-detection, O2 self-supply and enhanced phototherapy. PAPD nanosensor is constructed by encapsulating anthracene-based 1O2 sensitive fluorophore (DPA) into porphyrin metal-organic frameworks (PCN-224), decorating gold nanoparticles (AuNPs) as nanoenzymes, and coating polyethylene glycol thiol (PEG-SH) by the Au–S bond. PCN-224 serves as 1O2 reference fluorescence (FL) agent and photosensitizer. Once PCN-224-induced 1O2 is synthesized, the dual-channel ratiometric FL signal of PAPD actualizes sensitive, accurate and dynamic 1O2 visualization and gives real-time therapeutic information correlated with the therapeutic progression. Additionally, the catalase-like activity of PAPD possesses in situ O2 production via intracellular H2O2 decomposition and accelerates 1O2 yields for amplifying the tumor cell killing efficiency. Moreover, the ratiometric 1O2 self-detection affords the capacity to evaluate the O2 self-supplying effect in tumor 4T1 cells. Consequently, the rational-designed nanosensor PAPD provides a paradigm for real-time therapeutic evaluation and precise hypoxic tumor treatment clinically.