▎ 摘　　要

Enhanced cellular uptake efficiency of nanoparticles is important for their biomedical applications, including photothermal therapy (PTT) for cancer. In this study, a one-pot method was used to construct a positively charged and magnet-responsive nanocomposite comprising reduced graphene oxide anchoring iron oxide (RGI) with a polyethylenimine (PEI) modification, to improve the efficiency of cell internalization. The surface charge can be finely tuned using PEIs of different molecular weights. The obtained RGI(1.8k) composite (RGI modified by 1.8 kDa PEI) could load indocyanine green (ICG) at a high mass ratio of 10:3 and ablate cancer cells using low-density laser irradiation because of its positively charged surface. In addition, the hybrids of RGI1.8k and ICG could kill most cancer cells at a laser density of 0.7 W/cm(2) in vitro and 0.3 W/cm(2) in vivo. At the same time, cell viability could be controlled by converting the external magnetic-field direction because of the enrichment of the magnet-responsive composite in vitro and in vivo. Furthermore, RGI(1.8k)-ICGs could be used as T-2-weighted magnetic resonance and infrared thermal imaging agents. Coupled with the magnetic target effect, the imaging signal could be improved significantly. Therefore, RGI(1.8k)-ICGs represent a new highly efficient PTT and imaging agent with great potential for cancer treatment.