Gold nanoparticles coated with gadolinium-DTPA-bisamide conjugate of penicillamine (Au@GdL) as a T1-weighted blood pool contrast agentElectronic supplementary information (ESI) available: Scheme for Au@GdL, Maldi TOF mass spectrum of GdL, powder X-ray diffraction pattern of Au@GdL, visible absorption spectrum of Au@GdL, FT-IR spectra of GdL and Au@GdL, zeta potential of Au@GdL, TGA profile of Au@GdL, X-ray attenuation in HU for Au@GdL and Ultravist®, in vivo MR coronal images of mice obtained wi

The work is directed toward the synthesis and characterization of gold nanoparticles coated by Gd-chelate (Au@GdL), where L is a conjugate of diethylenetriamine- N , N , N ′, N ′′, N ′′-pentaacetic acid (DTPA) and penicillamine. Au@GdL is obtained by the replacement of citrate from Au@citrate with gadolinium chelate (GdL). The average size of Au@GdL is 12 nm with the loading of GdL reaching up to 3.0 × 10 3 per particle, and they exhibit very high r 1 relaxivity (∼10 7 mM −1 s −1 ) as well as X-ray attenuation. The r 1 relaxivity per [Gd] is 20.1 mM −1 s −1 . The small size of the present system also exhibits a USPIO-like behavior, such as contrast enhancement in the liver, the blood pool and the lymph node, as demonstrated by histological and TEM images, as well as CT and MR, rendering itself as a new class of T 1 multimodal CT/MR contrast agent with potential application to the blood pool and the lymph node. The average size of Au@GdL is 12 nm, with loading of GdL reaching up to 3.0 × 10 3 per particle, and they exhibit very high r 1 relaxivity (∼10 7 mM −1 s −1 ) as well as X-ray attenuation. This is as a new class of T 1 multimodal CT/MR contrast agent with potential application to the blood pool and the lymph node.