α-Fe Nanoparticles and Multiwalled Carbon Nanotubes Composite with Improved Photothermal Conversion Efficiency for Tumor Therapy

The efficiency of photothermal therapy based on conventional Fe₃O₄ nanoparticles (NPs) is limited due to their low absorption in the near-infrared (NIR) region. To surmount this obstacle, α-Fe nanoparticles/multiwalled carbon nanotubes (MWCNTs) composite is synthesized by incipient wetness impregnation (IWI). Due to improved extinction and heat generation mechanism (plasmons/electrons thermalization) of metallic Fe NPs with in nanocomposite structure, the photothermal conversion efficiency of Fe/MWCNTs composite is 87.98% (content: 60 μg/mL, 808 nm at power density of 1 W/cm²), which is highest among the previously reported Fe₃O₄ and other carbon-based nanostructures. The HaCaT cell viability after 72 h of coculturing is more than 91%, indicating the good biocompatibility of nanocomposite. The viability of B16-F10 melanoma cells is only 9.78% (808 nm laser irradiation for 15 min at 0.33 W/cm²), demonstrating the potential for hands-on applications.