Photoinduced Superhydrophilicity of Gd-Doped TiO2EllipsoidalNanoparticles BoostsT(1 )Contrast Enhancement for MagneticResonance Imaging

The unsatisfactory performance of current gadoliniumchelate basedT1contrast agents (CAs) for magnetic resonanceimaging (MRI) stimulates the search for better alternatives. Herein,we report a new strategy to substantially improve the capacity ofnanoparticle-basedT1CAs by exploiting the photoinduced super-hydrophilic assistance (PISA) effect. As a proof of concept, wesynthesized citrate-coated Gd-doped TiO2ellipsoidal nanoparticles(GdTi-SC NPs), whoser1increases significantly upon UVirradiation. The reduced water contact angle and the increasednumber of surface hydroxyl groups substantiate the existence of thePISA effect, which considerably promotes the efficiency of para-magnetic relaxation enhancement (PRE) and thus the imagingperformance of GdTi-SC NPs.In vivoMRI of SD rats with GdTi-SCNPs further demonstrates that GdTi-SC NPs could serve as a high-performance CA for sensitive imaging of blood vessels and accurate diagnosis of vascular lesions, indicating the success of ourstrategy