Multifunctional FeCo–Graphitic Carbon Nanocrystals for Combined Imaging, Drug Delivery and Tumor-Specific Photothermal Therapy in Mice

Ultrasmall FeCo–graphitic carbon shell nanocrystals (FeCo/GC) are promising multifunctional materials capable of highly efficient drug delivery in vitro and magnetic resonance imaging in vivo. In this work, we demonstrate the use of FeCo/GC for highly effective cancer therapy through combined drug delivery, tumor-selective near-infrared photothermal therapy, and cancer imaging of a 4T1 syngeneic breast cancer model. The graphitic carbon shell of the ~4 nm FeCo/GC readily loads doxorubicin (DOX) via π–π stacking and absorbs near-infrared light giving photothermal heating. When used for cancer treatment, intravenously administrated FeCo/GC–DOX led to complete tumor regression in 45% of mice when combined with 20 min of near-infrared laser irradiation selectively heating the tumor to 43–45 ℃. In addition, the use of FeCo/GC–DOX results in reduced systemic toxicity compared with free DOX and appears to be safe in mice monitored for over 1 yr. FeCo/GC–DOX is shown to be a highly integrated nanoparticle system for synergistic cancer therapy leading to tumor regression of a highly aggressive tumor model.