A Gd Al tetranuclear complex as a potential bimodal MRI/optical imaging agent

A new self-assembled gadolinium(iii)-aluminum(iii) complex (Gd Al) was synthesized and characterized. The efficacy of this Gd Al complex as a potential bimodal magnetic resonance imaging (MRI)/optical imaging agent has been evaluated. Relaxivity studies showed that the Gd Al complex has higher relaxation efficiency (7.18 mM s ) compared with the clinically used complex gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA, 3.9 mM s ) at 400 MHz and 25 °C. In vitro T -MR images on a 0.5 T magnetic field exhibited a remarkable enhancement of signal contrast for Gd Al compared to Gd-DTPA. Furthermore, the Gd Al complex exhibits bright-green luminescence with the emission spectrum centred at 510 nm. Live-cell fluorescence imaging reveals that the Gd Al complex is permeable to cells and localizes to the cytoplasm. In view of the relaxometric and luminescent properties, this Gd Al complex could serve as a potential bimodal MRI/optical imaging agent. © 2012 The Royal Society of Chemistry.