ALBERT

Description: 〈h3〉Abstract〈/h3〉 〈p〉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〈/sup〉∙s〈sup〉−1〈/sup〉 and a low 〈em〉r〈/em〉〈sub〉2〈/sub〉/〈em〉r〈/em〉〈sub〉1〈/sub〉 ratio of 1.27, both of which are critical for 〈em〉T〈/em〉〈sub〉1〈/sub〉-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 〈em〉T〈/em〉〈sub〉1〈/sub〉-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.〈/p〉 〈p〉 〈span〉 〈caption〉 〈strong〉Graphical abstract〈/strong〉 〈em〉 〈div〉Schematic presentation of the synthesis of Fe-CQDs and applications to magnetic resonance and fluorescent dual-mode imaging.〈/div〉 〈/em〉 〈/caption〉 〈span〉 〈img alt="" src="https://static-content.springer.com/image/MediaObjects/604_2019_3593_Figa_HTML.png"〉 〈/span〉 〈/span〉 〈/p〉