Folate conjugated Mn3O4@SiO2 nanoparticles for targeted magnetic resonance imaging in vivo

The monodisperse silica-coated manganese oxide nanoparticles (Mn3O4@SiO2 NPs) were synthesized via the high temperature pyrolysis approach and were aminated through silanization. The amine-functionalized Mn3O4 NPs enabled the covalent conjugation of hydrophilic methoxypoly(ethylene glycol) (PEG) and the targeting ligand of folate (FA) onto their surface. The formed PEG and FA modified Mn3O4 NPs (Mn3O4@SiO2(PEG)–FA) exhibited the good colloidal stability in the simulated biological medium and the targeting ability to HeLa cells overexpressed the FA receptor. The T1-weighted magnetic resonance (MR) imaging and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis of Mn3O4@SiO2(PEG)–FA NPs further demonstrated their targeting ability in tumor.