Gd and Eu Co Doped Nanoscale Metal Organic Framework as a T1 T2 Dual Modal Contrast Agent for Magnetic Resonance Imaging
Recently, a growing interest has been seen in the development of T1 T2 dual mode probes that can simultaneously enhance contrast on T1 and T2 weighted images. A common strategy is to integrate T1 and T2 components in a decoupled manner into a nanoscale particle. This approach, however, often requires a multi step synthesis and delicate nanoengineering, which may potentially affect the production and wide application of the probes. We herein report the facile synthesis of a 50 nm nanoscale metal organic framework (NMOF) comprising gadolinium (Gd3+ and europium (Eu3+ as metallic nodes. These nanoparticles can be prepared in large quantities and can be easily coated with a layer of silica. The yielded Eu,Gd NMOF@SiO2 nanoparticles are less toxic, highly fluorescent, and afford high longitudinal (38 mM 1s 1) and transversal (222 mM 1s 1) relaxivities on a 7 T magnet. The nanoparticles were conjugated with c(RGDyK) a tumor targeting peptide sequence, which has a high binding affinity toward integrin avb3. Eu,Gd NMOF@SiO2 nanoparticles, when intratumorally or intravenously injected, induce simultaneous signal enhancement and signal attenuation on T1 and T2 weighted images, respectively. These results suggest great potential of the NMOFs as a novel T1 T2 dual mode contrast agent.
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