Metal-Free Dual Modal Contrast Agents Based on Fluorographene Quantum Dots

The magnetic behavior of fluorographene quantum dots prepared from fluorinated graphene oxide (FGO) were explored. The structural and magnetic characterization of these quantum dots were carried out. Fluorographene quantum dots (FGQd) were prepared from FGO by simple liquid exfoliation. FGO was prepared by the oxidation of FG by an improved method. The synthesis of FGO yields two products, a hydrophilic less fluorinated grapheme oxide which settles to the bottom and a hydrophobic highly fluorinated graphene oxide which separates to the top. The highly fluorinated part, which separates to the top was then washed and used to prepare the quantum dots. The quantum dots were synthesized by a top down approach. FGO was bath sonicated in N-N dimethyl formamide (DMF) for 6 h. The hydrodynamic forces help to break down the larger flakes into smaller ones. The top three quarter of the solution, which would contain the smaller flakes was decanted. This was stirred on a hot plate at 110°C for 6 h. A disperse solution of the quantum dots and flakes in DMF was obtained. The low temperature magnetic measurements do not show any signature of magnetic ordering. The temperature dependent susceptibility of FGO derived quantum dots follow Curie's law, which confirms their paramagnetic nature. Density functional theory (DFT) studies show that this paramagnetism arises due to fluorine adatoms and presence of functional groups.