Carbon nanoparticles suspension injection for photothermal therapy of xenografted human thyroid carcinoma in vivo

Due to the unique structure, carbon nanomaterials could convert near‐infrared (NIR) light into heat efficiently in tumor ablation using photothermal therapy (PTT). Carbon nanoparticles suspension injection (CNSI) is a commercial imaging reagent for lymph node mapping. CNSI has similar structural characteristics to other carbon nanomaterials, and thus, might be applied as photothermal agent. Herein, we evaluated the photothermal conversion ability and therapeutic effects of CNSI on thyroid carcinoma. CNSI was composed by carbon nanoparticle cores and polyvinylpyrrolidone K30 as the dispersion reagent. CNSI absorbed NIR light efficiently following the Lambert‐Beer law. The temperature of CNSI dispersion increased quickly under the NIR irradiation. CNSI killed the TCP‐1 thyroid carcinoma cells under 808 nm laser irradiation at 0.5 W/cm(2), while CNSI or NIR irradiation treatment alone did not demonstrate this effect. Temperature increases were observed in tumor injected with CNSI under NIR irradiation. After three irradiation treatments, the tumor growth was completely blocked and the disruption of cellular structure was observed. When the tumor temperatures reached 53(°)C during treatment, the tumors did not recur within the observation period of 3 months. Our results suggested that CNSI might be used for PTT through “off label” use to benefit the patients immediately.