A redox-activated theranostic nanoplatform: toward glutathione-response imaging guided enhanced-photodynamic therapy

Abstract

Development of tumor microenvironment responsive and multi-mode imaging guided photodynamic therapy (PDT) is highly desired. Herein, we report a MnO₂-coated and redox-sensitive nanoagent (DCMn-RA) by growing MnO₂ on the surface of down-conversion nanoparticles (DCNPs) in situ for integrating GSH detection and enhanced-PDT. In tumor cells, the MnO₂ layer can be reduced by excess intracellular glutathione (GSH) to Mn²⁺, leading to an intense magnetic resonance (MR) signal as well as recovery of fluorescence of the Ru(II)-polypyridyl alkyne complex (RA) ([Ru(bpy)₂PIPB]·(PF₆)₂ (bpy = 2,2′-bipyridine and PIPB = prop-2-yn-1-yl 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)benzoate)) for imaging. Meanwhile, the progress of consuming GSH is beneficial for PDT because a high concentration of GSH would eliminate reactive oxygen species (ROS) generated by PDT. In addition, DCMn-RA possesses potential for NIR-II optical imaging upon tissue-penetrable 808 nm excitation. We believe that the research outcomes reveal its promising potential as an integrating theranostic nanoprobe and nanoagent to realize the detection of GSH and enhance the efficacy of PDT.