Biocompatible iron-doped carbon dots as T.sub.1-weighted magnetic resonance contrast agents and fluorescence imaging probes

• Published in: Mikrochimica acta (1966) 2019-08, Vol.186 (8)
• Main Authors: Huang, Qing, Liu, Yue, Zheng, Linling, Wu, Liping, Zhou, Zhengyu, Chen, Jiafei, Chen, Wei
• Format: Article
• Language: English
• Subjects: Ethylenediaminetetraacetic acid; Fluorescence; Investigations; Medical imaging equipment
• ISSN: 0026-3672
• DOI: 10.1007/s00604-019-3593-4

The one-pot synthesis of iron-doped carbon quantum dots (Fe-CQDs) for use as both magnetic resonance (MR) and fluorescent (dual-mode) imaging nanoprobes is described. Comprehensive characterizations of the material confirmed the successful doping of the CQDs with Fe(II) ions. The imaging probe has a longitudinal relaxivity of 3.92 mM.sup.-1*s.sup.-1 and a low r.sub.2/r.sub.1 ratio of 1.27, both of which are critical for T.sub.1-weighted contrast agents. The maximum emission of Fe-CQDs locates at 450 nm under 375 nm excitation, which also can be applied to fluorescence imaging. Biotoxicity assessment showed good biocompatibility of the Fe-CQDs. The in-vitro experiments with A549 cells indicated that the Fe-CQDs are viable candidates as dual-mode (MR/fluorescence) imaging nanoprobes. For in-vivo experiments, they exhibit high contrast efficiency, thereby improving the positive contrast in T.sub.1-weighted MR images. In-vivo time-dependent MRI of major organs showed that the Fe-CQDs undergo fast glomerular filtration and can evade immuno-absorption due to their ultra-small size and excellent biocompatibility.