Fluorescence-switchable ultrasmall fluorinated graphene oxide with high near-infrared absorption for controlled and targeted drug delivery

Although fluorinated graphene (FG) exhibits numerous excellent properties, its chemical inertness and hydrophobicity markedly limit its further application. Here, we report a novel strategy to synthesize nanosized water-soluble fluorinated graphene oxide (FGO) sheets that exhibit bright fluorescence (robust under both acidic and alkaline conditions), high near-infrared absorption and pH-responsive drug delivery. Structural adjustment of sizes into nanoscale (∼50 nm) endows FGO with superior photothermal performance surpasses those of FG and graphene oxide, and the fluorescence resonance energy transfer interactions between FGO and drugs allows switchable luminescence for monitoring the drug loading and release. The chemical introduction of oxygen facilitates the modification of FGO with folic acid for the first time and induces targeted endocytose into cancer cells. Enhanced hyperthermia, targeting specificity, and intracellular acid condition-triggered drug release guarantee the excellent therapeutic effects. Fine control over the structure and chemistry of FG, combined with high photoluminescence, enhanced photothermal effects, and targeted drug delivery makes our method potentially valuable in many fields.