Gold nanoparticles decorated with fluorinated poly(ethylene oxide): structural and functional insights

Fluorinated hybrid organic-inorganic nanomaterials have attracted interest for applications ranging from biomedicine to superhydrophobic surfaces. However, few examples of fluorinated hybrid nanoparticles (F-NPs) establish a clear relationship between the structure of the fluorinated component and the properties of the hybrid system. This gap limits understanding of structure-property correlations and hinders the development of F-NPs with tailored functionalities. Here, we report the design, synthesis, and characterization of gold NPs passivated with fluorinated thiolates (F-NP2), combining high fluorine content with excellent dispersibility in both organic and aqueous solvents. The gold core measures approximately 2 nm, while the hydrodynamic diameter is around 12 nm, consistent with SAXS data. Electron Spin Resonance (ESR) studies reveal an exceptionally strong interaction between a hydrophobic radical probe and the NP coating, surpassing previously reported systems and indicating a high capacity for hosting hydrophobic, drug-like molecules. Molecular dynamics simulations support this behavior, showing a highly folded fluorinated segment and limited shielding by the polar mPEG550 end, which also explains reversible aggregation at high NP concentrations observed via dynamic light scattering. Finally, preliminary ¹⁹F MRI data acquired at 7 T demonstrate a good signal-to-noise ratio, suggesting that these F-NPs may serve as sensitive fluorine-based tracking agents for biomedical applications.