Synthesis of FeOCl in Hollow Dendritic Mesoporous Organosilicon for Ascorbic Acid-Enhanced and MR Imaging-Guided Chemodynamic Therapy in Neutral pH Conditions.

Chemodynamic therapy (CDT) based on the Fenton reaction is a promising strategy for nonlight cancer treatment. However, the traditional Fenton reaction is only efficient in strongly acidic conditions (pH = 2-4), resulting in the limited curative effect in a weakly acidic tumor microenvironment (TME). Herein, we first developed a simple growth method to confine FeOCl nanosheets into hollow dendritic mesoporous organosilicon (H-DMOS) nanoparticles to obtain FeOCl@H-DMOS nanospheres. Ascorbic acid (AA) was then absorbed on the nanosystem as a HO prodrug and, meanwhile, was used for the regeneration of Fentons reagent for Fe. Finally, poly(ethylene glycol) (PEG) was coated on FeOCl@H-DMOS-AA to enhance the permeability and retention (EPR) effect in tumor tissue. The as-fabricated FeOCl@H-DMOS-AA/PEG can generate a large amount of highly toxic hydroxyl radicals (OH) by catalyzing HO even in neutral pH conditions with the help of AA. As a result, the effect of CDT has been markedly enhanced by the increased amount of HO and the efficient Fenton reaction in mild acidic TME, which can remove almost all of the tumors in mice. In addition, FeOCl also endows the nanosystem with -weighted MR imaging capability ( = 34.08 mM s), thus realizing the imaging-guided cancer therapy. All in all, our study may contribute a new direction and may have a bright future for enhanced CDT with a neutral pH range.