Self-Supplying of Hydrogen Peroxide/Oxygen Based on CaO2-Co3O4 Cascade Nanoreactors for Cellular Microenvironment Regulation

Monitoring and regulating levels of hydrogen peroxide and oxygen in cells can provide valuable information for cancer diagnosis, treatment, and development. However, it remains a significant challenge. In this study, a new nanocomposite (CaO2-Co3O4@HA) was developed by combining CaO2 nanoparticles and Co3O4 nanopolyhedrons and functionalization with hyaluronic acid (HA). The resulting nanoreactor can dynamically regulate contents of hydrogen peroxide and oxygen in cells. Due to the presence of HA, the synthesized CaO2-Co3O4@HA has good biocompatibility and active targeting ability. The CaO2 nanoparticles produce enough H2O2 in a slightly acidic (pH 6.5) environment, while the Co3O4 nanopolyhedrons with good catalase (CAT) mimic activity can effectively catalyze H2O2 into O2. The CaO2-Co3O4@HA then acted as a cascade nanoreactor for the self-supplying of hydrogen peroxide/oxygen. The process was monitored using H2O2 and O2 fluorescence probes and confirmed by fluorescence spectra and fluorescence confocal microscopy. This study not only verifies that the nanoreactor has a high ability to self-supply H2O2 and catalyze the generation of oxygen via the metal oxides under slightly acidic conditions but also provides a new way to regulate the contents of oxygen and hydrogen peroxide in cells. The tandem nanoreactor may have potential implications for cancer diagnosis and treatment through the regulation of reactive oxygen species in the cellular microenvironment.