Biocompatible Fe3+–TA coordination complex with high photothermal conversion efficiency for ablation of cancer cells

Schematic of the synthetic route of Fe3+–TA (Tannic Acid) complex with significant photothermal effect upon near-infrared (NIR) laser irradiation. [Display omitted] •Fe3+–TA complex was synthesized rapidly by a one-step method with natural reagents.•Fe3+–TA complex exhibited a photothermal conversion efficiency as high as 77.3%.•Fe3+–TA complex showed excellent photothermal stability and ultralow cytotoxicity.•The photothermal ablation efficacy of Fe3+–TA is adequate to photothermal therapy. Near-infrared (NIR) light absorbing nanomaterials, which can convert light to heat energy, have great prospects in biomedical applications. In the current work, Fe3+–TA (Tannic Acid) coordination complex formed by simple mixing of tannic acid and FeCl3 solutions was explored as a novel photothermal agent. Due to the strong absorbance in the near-infrared region induced by the coordination effect between TA molecule and Fe3+ ion, the as-prepared Fe3+–TA complex exhibited excellent photothermal performance with high photothermal conversion efficiency of 77.3% and high photothermal stability. Upon the exposure to Fe3+–TA aqueous dispersions with a concentration of 0.125 mg/mL, the cell mortality of HeLa cells was more than 85% after being irradiated for 10 min under NIR light (808 nm, 6 W cm−2). Besides, the Fe3+–TA complex exhibited ultralow cytotoxicity since only biocompatible tannic acid and iron ions were used as raw materials. Therefore, the merits of simple and convenient fabrication method, high photothermal conversion efficiency and excellent biocompatibility endow the high potential of Fe3+–TA complex as a photothermal agent for biomedical applications.