Cu₅FeS₄ Nanoparticles With Tunable Plasmon Resonances for Efficient Photothermal Therapy of Cancers

Localized surface plasmon resonances (LSPRs) in heavily doped copper chalcogenides are unique because LSPR energy can be adjusted by adjusting doping or stoichiometry. However, there are few investigations on the LSPRs of bimetal copper-based chalcogenides. Herein, bimetal Cu₅FeS₄ (CFS) nanoparticles were synthesized by a facile hot injection of a molecular precursor. The tunable plasmon resonance absorption of CFS nanoparticles is achieved by the decrease of the ratio of copper to iron and the treatment of n-dodecylphosphoric acid (DDPA). After surface modification with polyethylene glycol (PEG), the CFS nanoparticles with a plasmon resonance absorption peak at 764 nm can serve as promising photothermal agents, showing good biocompatibility and excellent photothermal performance with a photothermal conversion efficiency of up to 50.5%, and are thus used for photothermal therapy of cancers under the irradiation of an 808-nm laser. Our work provides insight into bimetal copper-based chalcogenides to achieve tunable LSPRs, which opens up the possibility of rationally designing plasmonic bimetal copper-based chalcogenides.