Synthesis of Fe-doped CuS nanoparticles for the combination of photothermal and chemodynamic therapy

Copper sulfide (CuS) nanoparticles with strong absorption in the near-infrared region were synthesized in oleic acid (OA)-oleylamine (OM)-octadecene (ODE) system using copper acetylacetonate and sulfur powder as copper and sulfur sources respectively. By adjusting the activation solvent for the sulfur powder, the absorption peak can be tuned to around 1 064 nm which was beneficial for photothermal therapy. The Fe and Mn elements doped CuS nanoparticles were further prepared by the cation exchange approach, and the absorption peak can be retained after the reaction. Then, these hydrophobic nanoparticles were transferred into an aqueous solution by the microemulsion method, the obtained PEGylated (PEG=poly(ethylene glycol)) nanoparticles exhibited excellent dispersity and colloidal stability. Their photothermal performance and the hydroxyl radical (center dot OH) production before and after Fe3+-doping were investigated thereafter. The mass extinction coefficient of Fe3+-doped CuS nanoparticles after PEGylation (CuS:Fe-PEG) at 1 064 nm was 37.5 L.g(-1).cm(-1), with a high photothermal conversion efficiency of around 43.7%. Although these values were slightly decreased compared with undoped CuS-PEG, their ability to produce center dot OH was significantly improved. A higher inhibition ratio of cancer cells was observed with CuS:Fe-PEG nanoparticles under weak acid condition. And under 1 064 nm laser, these nanoparticles can kill cancer cells more effectively. Therefore, the prepared CuS:Fe-PEG nanoparticles can be used for the combination of photothermal and chemodynamic therapy.