Gold nanoparticles functionalised with stable, fast water exchanging Gd super(3+) chelates as high relaxivity contrast agents for MRI

Gold nanoparticles functionalized with Gd super(3+) chelates displaying fast water exchange, superb pH stability and inertness towards transmetalation with Zn super(2+) have been prepared and characterized as a new high relaxivity (29 mM super(-1) s super(-1), 30 MHz, 25 degree C) contrast agent potentially safe for in vivoMRI applications. The Lipari-Szabo treatment for internal rotation was used to evaluate the effect of linker flexibility on the relaxivity of the gold nanoparticles. The effect of fast water exchange on the relaxivity of gold nanoparticles functionalized with Gd super(3+) chelates is also addressed in this communication.