Monodisperse Hollow MnO2 with Biodegradability for Efficient Targeted Drug Delivery.

The development of new nanocarriers with desired degradability and targeted ability is of great significance for efficient drug delivery. In this work, a monodisperse hollow structured MnO2 (H-MnO2) with a mesoporous shell is prepared and functionalized for efficient targeted drug delivery. The highly monodisperse H-MnO2 with a uniform morphology was obtained by in situ growing MnO2 on solid silica nanoparticles and subsequently removing the silica core. Then, the H-MnO2 is successively modified with polyethylene glycol and targeted molecule folate (FA). The resultant H-MnO2-FA shows excellent colloidal stability and high drug-loading content (∼58.2%) of the antitumor drug doxorubicin hydrochloride (DOX). The H-MnO2-FA possesses acid-responsive T1-weighted magnetic resonance imaging ability. The pH-dependent biodegradation behavior of H-MnO2-FA is directly observed in vitro and confirmed by in vivo imaging, which is expected to favor the potential clearance of this hollow structured nanocarrier and eliminate its long-term toxicity. In addition, the DOX-loaded H-MnO2-FA also demonstrates excellent cancer cell-killing effect and tumor inhibition efficacy.