Tunable fabrication of new theranostic Fe3O4-black TiO2 nanocomposites: dual wavelength stimulated synergistic imaging-guided phototherapy in cancer

The development of a simplified theranostic system with high-efficiency for multifunctional imaging-guided photodynamic therapy/photothermal therapy (PDT/PTT) is a great challenge. Therefore, a versatile fabrication strategy was introduced to design new Fe3O4-black TiO2 nanocomposites (Fe–Ti NCs). The Fe–Ti NCs exhibit an intense broad light absorption, high photothermal conversion efficiency, inherited phototherapy, and favorable magnetic resonance imaging (MRI) properties. The in vitro results demonstrate synergistic PTT and PDT capability of Fe–Ti NCs under 808 nm irradiation at low concentration and power density. Fe–Ti NCs also show superior phototherapy performance (PTT/PDT) under 671 nm laser irradiation. The confocal microscopy analysis demonstrates reactive oxygen species (ROS)-mediated synergistic phototherapy. Hematological and histological analysis confirms no evident toxicity of Fe–Ti NCs. The in vivo photoinduced tumor ablation capability of Fe–Ti NCs was assessed and monitored, and a rapid increase in temperature (60 ± 2 °C) after being exposed to 808 nm laser at 0.7 W cm−2 for 5 min was observed. Then, the same change in temperature is observed under 671 nm laser at 0.5 W cm−2. Thus, in vitro and in vivo dual-wavelength laser tumor ablation ability of Fe–Ti NCs verified excellent synergistic phototherapy efficacy against tumors. Moreover, Fe–Ti NCs exhibit superparamagnetic behavior, high magnetization value (48 emu g−1), good r2 relaxivity value (38.2 mM−1 s−1), and excellent T2 imaging capability to monitor therapeutic performance.