Bioinspired synthesis of gadolinium-based hybrid nanoparticles as MRI blood pool contrast agents with high relaxivity

A unique biomineralization approach was developed to synthesize gadolinium-based hybrid (GH) nanoparticles for effective blood pool contrast agents. This approach is bioinspired, environmentally benign, and straightforward. As-prepared GH nanoparticles are biocompatible and well stable in serum. They exhibit much higher longitudinal relaxivity and transverse relaxivity in water (r(1) and r(2) values of 15.0 and 19.7 s(-1) per mM of Gd3+, respectively) than those measured for Gd-DTPA solution (r(1) and r(2) values of 3.7 and 4.6 s(-1) per mM of Gd3+, respectively). In vivo T-1-weighted magnetic resonance imaging (MRI) in living mice shows that the GH nanoparticles have an intravascular half-life up to 1 h, much longer than that of Gd-DTPA (about 10 min). As the GH nanoparticles were found to be cleared gradually via hepatobiliary (HB) processing, they can also serve as ideal candidates for liver specific MR contrast agents. In particular, these GH nanoparticles are bioinspired and environmentally benign, therefore promising for medical imaging applications.