Simultaneous control of morphology, phase and optical absorption of hydrophilic copper sulfide-based photothermal nanoagents through Cu/S precursor ratios

Abstract Photothermal ablation (PTA) therapy has a great potential to revolutionize conventional therapeutic approaches for cancers, and a prerequisite is to obtain efficient photothermal nanoagents. For the preparation of hydrophilic copper sulfide-based photothermal nanoagents, we have developed a simple solvothermal route with the mixture of water/ethanol/polyethylene glycol (molecular weight 400, abbreviated as PEG-400) as the solvent. By adjusting Cu/S precursor ratio from 1/5 to 1/1, we have realized the simultaneous control of morphology (from octahedral-like particles, nanoplates to nanoparticles), phase (from digenite Cu 9 S 5 to covellite CuS) and optical absorption (from no NIR absorption to strong NIR absorption). When Cu/S precursor ratio is 1/1, the resulting sample has the smallest size (∼40 nm), excellent hydrophilicity and the highest photoabsorption in NIR region. The aqueous dispersion containing CuS nanoparticles exhibits excellent photothermal conversion performance under the irradiation of 980 nm laser, for example, the temperature of the aqueous dispersion of CuS nanoparticles (0.20 g/L) can increase by 18.0 °C at 360 s under the irradiation of 980 nm laser with power density of 1.50 W cm −2 . Therefore, this kind of CuS nanoparticles has great potential as the photothermal nanoagents for PTA of cancer cells.