CoFe2O4@MnFe2O4/polypyrrole nanocomposites for in vitro photothermal/magnetothermal combined therapy

CoFe2O4@MnFe2O4/polypyrrole nanocomposites, in which CoFe2O4@MnFe2O4 core/shell nanoparticles (NPs) were well-distributed in/on polypyrrole (PPy) nanoparticles, have been prepared by the polymerization of pyrrole by Fe3+ in the presence of polyvinyl alcohol (PVA) and CoFe2O4@MnFe2O4 NPs. In CoFe2O4@MnFe2O4/polypyrrole nanocomposites, the PPy with strong near-infrared absorption can convert 808 nm laser irradiation to heat with a photothermal conversion efficiency of ∼38%, and the CoFe2O4@MnFe2O4 NPs can convert the electromagnetic energy to heat simultaneously in an alternating magnetic field (200 kHz, 60.6 kA m−1) with a specific loss power of 930 W g−1. In vitro experiments showed that the cell viability of 4T1 cells incubated with 200 μg mL−1 of nanocomposites was ∼58% when irradiated by an 808 nm laser (0.2 W cm−2) for 10 min, and ∼68% in an alternating magnetic field (200 kHz, 60.6 kA m−1) for 0.5 h. A combination of 808 nm laser irradiation and alternating magnetic field can ablate nearly all the cells, which suggests the synergistic effect of photothermal and magnetothermal combined therapy.