Carbon Quantum Dots Codoped with Nitrogen and Lanthanides for Multimodal Imaging

Nanoparticles are increasingly being used as advantageous alternatives to commonly used contrast agents in bioimaging, not only due to their improved imaging capabilities but also their great potential in theranostics. Herein, carbon quantum dots (CQDs) codoped with nitrogen and lanthanides (i.e., Gd and Yb) are synthesized using a one-pot microwave-assisted hydrothermal method and evaluated as improved multimodal contrast agents for imaging purposes. The obtained doped-CQDs exhibit an intense fluorescence emission with excellent quantum yields (66 +/- 7%) along with outstanding magnetic resonance (MR) and computed tomography (CT) contrast properties, without showing appreciable cytotoxicity after their exposure to three different cell lines for 24 and 72 h. Such outstanding features turn these nanoparticles into ideal labels for multimodal imaging. To actually prove such potential, first, these CQDs codoped with N and lanthanides are successfully applied to in vitro fluorescence, and MR and CT cell imaging. In addition, such nanoparticles demonstrate to have great potential as contrast agents for multimodal imaging in vivo as significant MR and CT contrast enhancement is observed in the bladder and kidneys of a mouse after their intravenous injection into the tail vein.