Exfoliated FePS 3 nanosheets for T 1 -weighted magnetic resonance imaging-guided near-infrared photothermal therapy in vivo

Developing bifunctional nanoplatforms integrating advanced biological imaging with high-performance therapeutic functions is interesting for nanoscience and biomedicine. Herein, thin-layered FePS 3 nanosheets modified with amine polyethylene glycol (FePS 3 -PEG) are synthesized by ultrasonicated exfoliation of bulk FePS 3 single crystals under Ar atmosphere and in situ chemical functionalization with amine PEG. The prepared FePS 3 -PEG nanosheets give a photothermal conversion efficiency of 22.1% under 808-nm laser and evident T 1 relaxation ( r 1 = 2.69 (mmol L −1 ) −1 S −1 ) in external magnetic fields. Biologically experimental results in vitro and in vivo demonstrate that FePS 3 -PEG nanosheets have good biocompatibility and exhibit excellent photothermal therapy (PTT) effect under clear T 1 weighted magnetic resonance imaging (MRI). The characteristics of FePS 3 -PEG nanosheets enable them to be a promising nanomedicine for T 1 -weighted MRI-guided near-infrared PTT of cancers.