Magnetic nanoclusters engineered by polymer-controlled self-assembly for the accurate diagnosis of atherosclerotic plaques via magnetic resonance imaging.

Oleyl dextran-coated magnetic nanoclusters (ODMCs) are fabricated for the accurate detection of macrophage-rich atherosclerotic plaques using magnetic resonance (MR) imaging. Dextran is introduced to the cluster surface of magnetic nanocrystals (MNCs) through self-assembly using amphiphilic oleic acid-conjugated dextran (ODex) to provide not only hydrophilicity but also a high affinity to macrophages. Enhanced magnetism of the ODMCs is engineered by optimizing the degree of substitution (DS) of the oleyl group in ODex and the concentration of ODex used for the synthesis of ODMC. Consequently, ODMCs exhibit significantly increased T2 relaxivity and excellent macrophage-targeting ability without cytotoxicity, in vitro. Moreover, in vivo T2-weighted MR imaging after intravenous injection of ODMCs into a rat artery balloon injury model demonstrates considerable MR contrast strength efficacy in the plaques of the injured carotid artery. These novel ODMCs may offer a highly efficient MR imaging nanoprobes for the selective diagnosis of atherosclerosis.