Surface functionalized hollow manganese oxide nanoparticles for cancer targeted siRNA delivery and magnetic resonance imaging.

Multifunctional hollow manganese oxide nanoparticles (HMON) were produced by a bio-inspired surface functionalization approach, using 3,4-dihydroxy-L-phenylalanine (DOPA) as an adhesive moiety, for cancer targeted delivery of therapeutic siRNA and simultaneous diagnosis via magnetic resonance imaging (MRI). Cationic polyethylenimine-DOPA conjugates were stably immobilized onto the surface of HMON due to the strong binding affinity of DOPA to metal oxides, as examined by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. These nanoparticles were subsequently functionalized with a therapeutic monoclonal antibody, Herceptin, to selectively target cancer cells. Confocal microscopy and MR imaging studies revealed that the surface functionalized HMON enabled the targeted detection of cancer cells in T(1)-weighted MRI as well as the efficient intracellular delivery of siRNA for cell-specific gene silencing. These nanomaterials are expected to be widely exploited as multifunctional delivery vehicles for cancer therapy and imaging applications.