Photothermal therapy of xenografted tumor by carbon nanoparticles-Fe(II) complex

Due to the unique structure, carbon nanomaterials could convert near-infrared (NIR) light into heat efficiently in tumor ablation using photothermal therapy (PTT). However, none of them has been applied in clinical treatment, because they have not been approved for clinical evaluations and the precise temperature control facility is scarce. In this study, we designed a temperature-responsive controller for PTT and used carbon nanoparticles-Fe(II) complex (CNSI-Fe) as photothermal conversion agent (PTA) for PTT of tumor in vitro and in vivo. CNSI-Fe was an innovative drug under the evaluations in clinical trials. CNSI-Fe showed excellent photothermal conversion ability in water to increase the water temperature by 40 °C within 5 min under irradiation of 808 nm laser at 0.5 W/cm². The temperature was precisely controlled at 52 °C for both in vitro and in vivo tumor inhibition. CNSI-Fe with NIR irradiation showed higher tumor cell inhibition than CNSI. In tumor bearing mice, CNSI-Fe with NIR irradiation achieved an inhibition rate of 84.7 % and 71.4 % of them were completely cured. Mechanistically, CNSI-Fe under NIR irradiation induced the radical generation, oxidative damage and ferroptosis to kill tumor. In addition, CNSI-Fe showed good biosafety during PTT according to hematological, serum biological and histopathological examinations. These results indicated that the combination of chemotherapy and PTT provided higher antitumor efficiency using CNSI-Fe as PTA.