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Keywords:

  • nanoscale coordination polymers;
  • magnetic resonance imaging;
  • dual contrast;
  • tumor imaging

Development of multifunctional nanoscale coordination polymers (NCPs) allowing for T1- and T2-weighted targeted magnetic resonance (MR) imaging of tumors could significantly improve the diagnosis accuracy. In this study, nanoscale coordination polymers (NCPs) with a diameter of ≈80 nm are obtained with 1,1′-dicarboxyl ferrocene (Fc) as building blocks and magnetic gadolinium(III) ions as metallic nodes using a nanoprecipitation method, then further aminated through silanization. The amine-functionalized Fc-Gd@SiO2 NCPs enable the covalent conjugation of a fluorescent rhodamine dye (RBITC) and an arginine-glycine-aspartic acid (RGD) peptide as a targeting ligand onto their surface. The formed water-dispersible Fc-Gd@SiO2(RBITC)–RGD NCPs exhibit a low cytotoxicity, as confirmed by MTT assay. They have a longitudinal relaxivity (r1) of 5.1 mM−1 s−1 and transversal relaxivity (r2) of 21.7 mM−1 s−1, suggesting their possible use as both T1-positive and T2-negative contrast agents. In vivo MR imaging experiments show that the signal of tumor over-expressing high affinity αvβ3 integrin from T1-weighted MR imaging is positively enhanced 47±5%, and negatively decreased 33±5% from T2-weighted MR imaging after intravenous injection of Fc-Gd@SiO2(RBITC)–RGD NCPs.