Dual T1 and T2 weighted magnetic resonance imaging based on Gd3+ loaded bioinspired melanin dots

In this report, a novel T-1/T-2 dual modal nanoprobe based on highly efficient and bioinspired melanin dots (M-dots) with directly loading gadolinium (Gd-M-dots) for magnetic resonance imaging (MRI) is described. In vitro and in vivo investigations have revealed that Gd-M-dots showed nontoxicity and good biocompatibilitity. Gd-M-dots relaxivity values on 3 T were determined to be r(1) = 23.4 and r(2) = 123.3 mM(-1) s(-1), which were much higher than both Gd-DTPA (r(1) = 5.1, r(2) = 6.2 mM(-1) s(-1)) and Fe-M-dots (r(1 )= 1.2, r(2) = 2.1 mM(-1) s(-1)). For in vivo MRI, after injection of Gd-M-dots, simultaneous T-1 and T-2 contrast enhancement have been observed in the MRI of mice abdomen and mice bearing U87MG tumors. Furthermore, all the veins showed high signal intensity on T-1-weighted MRI and remained for 2 h. Overall, in vitro and in vivo studies indicate that Gd-M-dot with high r(1) relaxivity and r(2) relaxivity has high potential to he a promising nanoprobe for MR venography and molecular imaging. (C) 2018 Elsevier Inc. All rights reserved.