Effect of Ligand Structure on MnO Nanoparticles for Enhanced T1 Magnetic Resonance Imaging of Inflammatory Macrophages

Carboxymethyl-dextran (CM-dextran) replaced the hydrophobic oleylamine ligands on the surfaces of MnO nanoparticles, rendering them highly water-soluble by allowing direct contact with excited water protons. Solution MRI studies of the two types of nanoparticles, exchanged and bilayered, with different core sizes have shown that the exchanged ligand structure exhibits significantly enhanced longitudinal relaxation. The modification with dextran converted the nanoparticles into effective T1 MRI contrast agents, as well as promoting strong interactions with macrophages. Thus, it is a potential MR contrast agent for visualizing inflammatory macrophages.