Folate grafted Prussian Blue entrapped with gadolinium(III) as a new contrast agent for tumor-targeted magnetic resonant imaging.

A new generation of magnetic resonant imaging (MRI) contrast agents will simultaneously possess characteristics of high relaxivity, biotargeting ability and nontoxicity, referring that they are helpful to acquire better contrast imaging in the region of interest (e.g., tumors) without health risks. Colloidal Prussian blue with quasi-zeolite structure was introduced as a new type of nanosized scaffold to entrap Gd(III) ions via ion exchange and folate, one kind of cancer-targeting ligand, was intentionally grafted on its surface. The nanoparticulate contrast agent has T1 relaxivity of up to 23.9 mM(-1) s(-1). In vivo MRI illustrated a clear contrast enhancement specifically on the ovarian tumors transplanted on mice at a low dose. Furthermore, the contrast agent is stable and free of cytotoxicity. Therefore it might be a promising new MRI contrast agent for clinical applications.