Albumin-Assisted Synthesis of Ultrasmall FeS2 Nanodots for Imaging-Guided Photothermal Enhanced Photodynamic Therapy

Current mainstream cancer treatment methods have their limitations. New approaches are thus desired to assist our battle against cancer. Herein, multifunctional ultrasmall FeS2 nanodots with the size of 7 nm are synthesized by biomineralization and used for imaging-guided combined tumor therapy. Bovine serum albumin (BSA), which acts as the reaction template to induce the mineralization of FeS2 nanomaterials under alkaline conditions, could also be used as a drug delivery system for coupling photosensitive molecule such as Chlorin e6 (Ce6). Taking advantage of the near-infrared (NIR) absorbance and the high r2 relaxivity of the synthesized ultrasmall FeS2 nanodots, as well as the Ce6 fluorescence, in vivo trimodal imaging of optical/magnetic resonance/photoacoustics was carried out, showing efficient tumor accumulation of FeS2@BSA-Ce6 after intravenous injection. In vitro and in vivo photothermal and photodynamic therapy were then conducted for synergistic tumor therapy and did not cause any apparent toxicity to the treated animals. Our work thus provides a new kind of ultrasmall FeS2 multifunctional nanodot modified by albumin via a simple method, promising for combination phototherapy as well as cancer theranostics.