Mn(3)[Co(CN)(6)](2)@SiO(2) Core-shell Nanocubes: Novel bimodal contrast agents for MRI and optical imaging

Nanoprobes with dual modal imaging of magnetic resonance imaging (MRI) and two-photon fluorescence (TPF) can serve as promising platforms for clinical diagnosis. A wide range of molecules and nanoparticles have been investigated as agents for contrast enhanced MRI and fluorescence imaging in cancer diagnosis. However, a single material with dual modal imaging of MRI and TPF is rarely reported. We found that Mn(3)[Co(CN)(6)](2) nanocubes can serve as agents for both T(1)- and T(2)-weighted MRI, and TPF imaging. The nanocubes coated with silica to form Mn(3)[Co(CN)(6)](2)@SiO(2) core-shell nanocubes were readily internalized by cells without showing cytotoxicity. In vitro tests, the core-shell nanocubes display relatively high longitudinal (r(1)) and transverse (r(2)) relaxivities, they also manifest a remarkable T(1) and T(2) contrast effects at in-vivo imaging of internal organs in Mice. Moreover, the core-shell nanocubes could offer high-resolution cell fluorescence imaging by two-photon excitation (720 nm) or by conventional fluorescence with 403- or 488-nm excitation.