Aptamer-conjugated Mn3O4@SiO2 core–shell nanoprobes for targeted magnetic resonance imaging

The objective of this study was to evaluate the targeted T1-magnetic resonance imaging (MRI), quantitative biodistribution and toxicity of aptamer (AS411) conjugated Mn3O4@SiO2 core–shell nanoprobes (NPs) in human cervical carcinoma tumor-bearing mice. The NPs were firstly prepared by encapsulating a hydrophobic Mn3O4 core within an amino functionalized silica shell. The fluorophore rhodamine (RB) was doped into the silica shell and the amphiphilic polymer poly(ethylene glycol) (PEG) was modified on the surface of the shell to improve its biocompatibility, then the aptamer AS411 was conjugated onto the end of the PEG chains as targeting ligands. The final NPs were abbreviated as Mn3O4@SiO2(RB)–PEG–Apt. By means of in vitro fluorescence confocal imaging and in vivo MRI, the NPs have been demonstrated to target cancer cells and prominent tumor aggregation effectively. The imaging results were further confirmed by a quantitative biodistribution study. In addition, histological, hematological and biochemistry analysis also proved the low toxicity of NPs in vivo. Our results showed the great potential of the Mn3O4@SiO2(RB)–PEG–Apt NPs could be used as a multifunctional nanoplatform for long-term targeted imaging and therapy of cancer.