Gold nanoparticles functionalized by gadolinium–DTPA conjugate of cysteine as a multimodal bioimaging agent

Abstract: The synthesis and characterization of gold nanoparticles coated with Gd-chelate (Au@GdL), where L is a conjugate of DTPA and cysteine, is described. These particles are obtained by the replacement of citrate from the gold nanoparticle surfaces with gadolinium chelate (GdL). The average size of Au@GdL is 14nm with a loading of GdL reaching up to 2.9×103 per particles, and they demonstrate very high R1 relaxivity (∼105 mM−1 s−1) as well as X-ray attenuation. The R1 relaxivity per [Gd] is 17.9mM−1 s−1. The present system also exhibits macrophage-specific property, as demonstrated by histological and TEM images as well as CT and MR, rendering itself as a new class of T1 multimodal CT/MR contrast agent. [Copyright &y& Elsevier]