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

Photodynamic therapy (PDT) holds promise in biochemical study and tumor treatment. A novel multifunctional nanosystem CaO2/MnO2@polydopamine (PDA)-methylene blue (MB) nanosheet (CMP-MB) was designed. CaO2 nanoparticles were encapsulated by MnO2 nanosheet, and then PDA was coated on the surface of CaO2/MnO2 nanosheets, which could adsorb photosensitizer MB through hydrophobic interaction or - stacking. In this nanosystem, CaO2/MnO2 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 MnO2, 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. (C) 2018 Wiley Periodicals, Inc.