Catechin tuned magnetism of Gd-doped orthovanadate through morphology as T₁-T₂ MRI contrast agents

Tetragonal (t)-LaVO₄ has turned out to be a potential host for luminescent materials. Synthesis of t-LaVO₄ till date has been based on chelating effect of EDTA making it not ideal for bioimaging applications. An alternative was proposed by us through the use of catechin. In recent times there is interest for new MRI contrast agents that can through appropriate doping function both as MRI contrast and optical/upconversion materials. It is generally believed that under appropriate doping, t-LaVO₄ would be a better upconversion material than monoclinic (m)-LaVO₄. Based on these postulations, this work explores the use of gadolinium doped t-LaVO₄ as an MRI contrast agent. From literature, gadolinium oxide is a good T₁ contrast agent. Through this work, using catechin as a template for the synthesis of Gd doped t-LaVO₄, we demonstrate the possible use as a T₁ contrast agent. Interestingly, as the catechin concentration changes, morphology changes from nanorods to square nanoplates and spheres. In this process, a switch from T₁ to T₂ contrast agent was also observed. Under optimal concentration of catechin, with a rod shaped Gd doped t-LaVO₄ an r₂/r₁ value of 21.30 was observed. Similarly, with a spherical shape had an r₂/r₁ value of 1.48 was observed.