Preparation and characterization of MRI-active gadolinium nanocomposite particles for neutron capture therapy

We demonstrate the synthesis and characteristics of MRI-active Gd ₂O₃ core/SiO₂ shell/poly(2-methacryloyloxyethyl phosphorylcholine) corona composite nanoparticles (Gd₂O ₃@SiO₂@PMPC NPs). The prepared NPs have a number of attractive features in cancer diagnosis and neutron capture therapy (NCT): biocompatibility, colloidal stability, low cytotoxicity, nucleus affinity, passive targeting, etc. Monodisperse and highly crystalline Gd₂O ₃ NPs were prepared using a polyol protocol to control the average particle size and surface properties. The Gd₂O₃ NPs were then functionalized with SiO₂ and a biomimetic layer of PMPC, to achieve reduced toxicity and enhanced nucleus affinity, for use as an MRI-active Gd-NCT agent. The size of the NPs was tailored to be from 50 to 100 nm for passive accumulation in tumor tissue through loosened capillary vessels. The morphologies and structures of Gd₂O₃, Gd₂O ₃@SiO₂-Br, and Gd₂O₃@SiO ₂@PMPC NPs were studied by FT-IR, XRD, HR-TEM, and TGA. In vitro cytotoxicity was investigated with three kinds of normal and cancer cells, and in vitro and in vivo MRI analyses were performed to confirm the contrast ability, accumulation, and sustentation of NPs in tumor tissues.