Designing highly stable ferrous selenide-black phosphorus nanosheets heteronanostructure via P-Se bond for MRI-guided photothermal therapy

BACKGROUND: The design of stable and biocompatible black phosphorus-based theranostic agents with high photothermal conversion efficiency and clear mechanism to realize MRI-guided precision photothermal therapy (PTT) is imminent. RESULTS: Herein, black phosphorus nanosheets (BPs) covalently with mono-dispersed and superparamagnetic ferrous selenide (FeSe(2)) to construct heteronanostructure nanoparticles modified with methoxy poly (Ethylene Glycol) (mPEG-NH(2)) to obtain good water solubility for MRI-guided photothermal tumor therapy is successfully designed. The mechanism reveals that the enhanced photothermal conversion achieved by BPs-FeSe(2)-PEG heteronanostructure is attributed to the effective separation of photoinduced carriers. Besides, through the formation of the P-Se bond, the oxidation degree of FeSe(2) is weakened. The lone pair electrons on the surface of BPs are occupied, which reduces the exposure of lone pair electrons in air, leading to excellent stability of BPs-FeSe(2)-PEG. Furthermore, the BPs-FeSe(2)-PEG heteronanostructure could realize enhanced T(2)-weighted imaging due to the aggregation of FeSe(2) on BPs and the formation of hydrogen bonds, thus providing accurate PTT guidance and generating hyperthermia to inhabit tumor growth under NIR laser with negligible toxicity in vivo. CONCLUSIONS: Collectively, this work offers an opportunity for fabricating BPs-based heteronanostructure nanomaterials that could simultaneously enhance photothermal conversion efficiency and photostability to realize MRI-guided cancer therapy. GRAPHIC ABSTRACT: [Image: see text] SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12951-021-00905-5.