Thermodynamic stability and kinetic inertness of a Gd–DTPA bisamide complex grafted onto gold nanoparticles

Gold nanoparticles coated by gadolinium (III) chelates (Au@DTDTPA) where DTDTPA is a dithiolated bisamide derivative of diethylenetriamine‐N,N,N′,N′′,N′′‐pentaacetic acid (DTPA), constituted contrast agents for both X‐ray computed tomography and magnetic resonance imaging. In an MRI context, highly stable Gd3+ complexes are needed for in vivo applications. Thus, knowledge of the thermodynamic stability and kinetic inertness of these chelates, when grafted onto gold nanoparticles, is crucial since bisamide DTPA chelates are usually less suited for Gd3+ coordination than DTPA. Therefore, these parameters were evaluated by means of potentiometric titrations and relaxivity measurements. The results showed that, when the chelates were grafted onto the nanoparticle, not only their thermodynamic stability but also their kinetic inertness were improved. These positive effects were correlated to the chelate packing at the nanoparticle surface that stabilized the corresponding Gd3+ complexes and greatly enhanced their kinetic inertness. Copyright © 2014 John Wiley & Sons, Ltd. A dithiolated bisamide DTPA (namely DTDTPA) grafted onto gold nanoparticles (namely Au@DTDTPA) and chelated by Gd(III) ions (namely Au@DTDTPA:Gd) was developed for both X‐ray computed tomography and magnetic resonance imaging. In comparison to the un‐grafted chelates, potentiometric and relaxometric studies demonstrated that thermodynamic stability and kinetic inertness of the grafted com...
Source: Contrast Media and Molecular Imaging - Category: Radiology Authors: Tags: Full Paper Source Type: research