Preparation of Ultrathin Two-Dimensional Ti x Ta1−x S y O z Nanosheets as Highly Efficient Photothermal Agents

High-yield preparation of solution-processed ultrathin 2D metal oxide/sulfide hybrid nanosheets, i.e. TixTa1-xSyOz (x=0.71, 0.49, 0.30), was reported via our developed electrochemical Li-intercalation method using TixTa1-xS2 layered bulk crystals as precursors. The obtained TixTa1-xSyOz nanosheets are composed of amorphous metal oxide and metal sulfide components containing a few crystalline TixTa1-xS2 domains. The Ti0.71Ta0.29SyOz nanosheet exhibits strong absorbance at the near-infrared regime, giving large extinction coefficient of 54.1 Lg-1cm-1 at 808 nm and high photothermal conversion efficiency of 39.2%. After modification with lipoic acid-conjugated polyethylene glycol, the Ti0.71Ta0.29SyOz nanosheet shows good photostability, enhanced physiological stability and negligible cytotoxicity under applied dosage, and then used as a highly efficient photothermal agent for photothermal treatment of cancer cells, including the Sk-mel-28 and HeLa, under 808 nm-laser irradiation.