Synthesis, characterization and in vitro toxicity of paramagnetic Au nanorods

Coated Au nanorods are widely known for their absorption in the near infrared1, making them excellent candidates for near infrared imaging and photo thermal therapy2. Furthermore, recent studies have shown that these nanomaterials are excellent candidates for Magnetic Resonance Imaging (MRI) since they can be used as T1 contrast agents when functionalized with Gd3+-containing moieties and as multimodal agents for MR-CT3 and MR-plasmonic4 imaging. In this context, our aim is to explore the possible incorporation of Gd3+ complexes to these nanosystems in order to use them as T1 contrast agents for MRI and, in a more advanced stage, as multimodal imaging agents. Here we describe the synthesis, characterization, properties and in vitro toxicity of paramagnetic nanorods coated, in one step, with combinations of thiol functionalized Gd3+ complexes of a 1,4,7,10-tetraazacyclododecane-1,4,7-tris(acetic acid) (DO3A)-based ligand and polyethylene glycol (PEG). Preliminary results show that these paramagnetic Au nanorods are biocompatible, show T1 contrast at low Gd3+ concentrations and are envisioned to become excellent candidates for multimodal purposes.