Open-Source and Reduced-Expenditure Nanosystem with ROS Self-Amplification and Glutathione Depletion for Simultaneous Augmented Chemodynamic/Photodynamic Therapy.

Reactive oxygen species (ROS)-induced cell apoptosis has emerged as an efficient strategy for cancer therapy. However, tumor hypoxia and insufficient amounts of endogenous hydrogen peroxide (H 2 O 2 ) in the tumor microenvironment are currently the main limitations of photodynamic therapy (PDT) and chemodynamic therapy (CDT). Moreover, the glutathione (GSH) scavenging effect on ROS further hinders the efficiency of ROS-mediated therapy. Here, a CaO 2 -based nanosystem (named as CF@CO@HC) with ROS self-amplification and GSH-depletion abilities was developed by a bottom-up approach. This hybrid nanoparticle consisted of a photosensitizer-doped calcium peroxide (CaO 2 ) core (CaO 2 -FM), a hybrid organosilica framework (Cu-ONS) incorporated with Fenton reagents (Cu 2+ ) and tetrasulfide groups, and a local hydrophobic cage (HC) shell. The photosensitizer was fluorescein derivative 4-FM with a thermally activated delayed fluorescence (TADF) property. The HC shell was built to protect the CaO 2 and the photosensitizer from being attacked by water. Upon being internalized into cancer cells, the nanosystem was decomposed through the reduction reactions of Cu 2+ and the tetrasulfide bond-doped silica shell by GSH, thus releasing Cu + for Cu + -mediated CDT. Meanwhile, the exposed CaO 2 -FM can react with H 2 O to liberate photosensitizer 4-FM and generate H 2 O 2 and O 2 to overcome barriers in CDT and PDT. Thus, our study provided an open-source and reduced-expenditure strategy via GSH depletion and ROS self-amplification behaviors for ROS generation and significantly achieved an improved synergistic PDT/CDT for cancers.