Interface-Engineered Mesoporous FeB with Programmed Drug Release for Synergistic Cancer Theranostics

The pursuit of mesoporous Fe-based nanoagents addresses the field of developing alternative Fe-bearing nanoagents for synergistic cancer therapy with the expectation that the use of an essential element may avoid the issues raised by the exogenous administration of other metal element-based nanoagents. Herein, we highlight the interface-engineered mesoporous FeB (mFeB) where the core mFeB is interfacially oxidized into an FeOOH nanosheet loaded with the chemotherapeutic drug doxorubicin (DOX) and further encapsuled within the double-sulfide-bonded SiO2 outer layer, denoted as mFeB@DOX-ss-SiO2, which can realize programmed drug release for synergistic cancer theranostics. When only in a tumor microenvironment, the nanoagent can be activated to release DOX from the mFeB and FeOOH nanosheets as well as expose the easily oxidized mFeB to spontaneously transform to FeOOH nanosheets with Fenton activity to facilitate chemodynamic therapy (CDT). In addition, the high photothermal conversion efficiency of mFeB@DOX-ss-SiO2 would promote CDT. Also, owing to the inherent nature of ferromagnetism and red fluorescence of DOX, mFeB@DOX-ss-SiO2 can realize T2-weighted magnetic resonance imaging and fluorescence imaging. In vivo mouse model experiments demonstrate that mFeB@DOX-ss-SiO2 with good biocompatibility realizing CDT/photothermal therapy/chemotherapy achieved complete tumor suppression. This study opens up a new way to explore theranostic nanoagents.