Self‐production of oxygen system CaO2/MnO2@PDA‐MB for the photodynamic therapy research and switch‐control tumor cell imaging

Abstract Photodynamic therapy (PDT) holds promise in biochemical study and tumor treatment. A novel multifunctional nanosystem CaO 2 /MnO 2 @polydopamine (PDA)‐methylene blue (MB) nanosheet (CMP‐MB) was designed. CaO 2 nanoparticles were encapsulated by MnO 2 nanosheet, and then PDA was coated on the surface of CaO 2 /MnO 2 nanosheets, which could adsorb photosensitizer MB through hydrophobic interaction or π‐π stacking. In this nanosystem, CaO 2 /MnO 2 had the ability of self‐production of oxygen, which solved the problem of tumor hypoxia largely. Moreover, it is worth mentioning that the fluorescence of MB was suppressed by MnO 2 , while its emission was triggered in the simulated tumor microenvironment. Therefore, CMP‐MB nanosheet could be used to switch‐control cell imaging potentially. 3‐(4,5‐dimethyl‐thiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide testing and Live/Dead assay confirmed CMP‐MB nanosheet had fewer side effects without illumination while it destroyed Hela cell with the illumination of light. Vitro cell experiment demonstrated CMP‐MB nanosheet could achieve tumor microenvironment responsive imaging and inhibit tumor cell growth under illumination effectively. Therefore, the system has great potential for PDT application and switch‐control tumor cell imaging. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2544–2552, 2018.