A pH-responsive CaO2@ZIF-67 system endows a scaffold with chemodynamic therapy properties

The insufficient of H 2 O 2 restricts the efficacy of chemodynamic therapy in tumor microenvironment. Calcium peroxide (CaO 2 ) is expected to solve this problem due to its H 2 O 2 -evolving ability. However, it prematurely decomposes in the moist air or water before reaching tumor site. In this study, zeolitic imidazolate framework-67 (ZIF-67) was in-situ grown on the surface of CaO 2 to construct a pH-responsive CaO 2 @ZIF-67 system and then incorporated into poly-L-lactic acid (PLLA) to prepare PLLA/CaO 2 @ZIF-67 scaffold by selective laser sintering technology. On the one hand, ZIF-67 is used as a chemodynamic therapy agent due to the release of cobalt ions after degradation. On the other hand, ZIF-67 can serve as protective layers to prevent premature decomposition of CaO 2 due to its hydrophobic properties, and then CaO 2 is exposed and reacts with water to form H 2 O 2 after the pH-responsive degradation of ZIF-67 under tumor acidic microenvironment. Results showed that the PLLA/CaO 2 @ZIF-67 scaffold could sustainedly produce H 2 O 2 under acidic pH and achieve 84.64% antitumor ratio against MG-63 cells. In addition, the scaffold also promoted proliferation and osteogenic differentiation of mouse bone marrow mesenchymal stem cells due to the release of calcium ions. The prepared PLLA/CaO 2 @ZIF-67 scaffold with chemodynamic antitumor and osteogenic effects has great potential to treat tumorous bone defect.