Thermochromism-induced temperature self-regulation and alternating photothermal nanohelix clusters for synergistic tumor chemo/photothermal therapy.

To improve the inherent defects of chemotherapy and photothermal therapy (PTT), we design a novel thermochromism-induced temperature self-regulation and alternating photothermal system based on iodine (I2)-loaded acetylated amylose nanohelix clusters (ILAA NHCs) under the guidance of molecular dynamic simulation in which I2 is loaded into the helical cavity of acetylated amylose (AA) by hydrophobic interaction. ILAA NHCs perform versatile photothermal conversion through their unique reversible thermochromism. Upon irradiation, I2 is gradually released and the ILAA NHCs turn into colorless. The laser is then penetrated deeply into the tissue for deep-seated heating, and the ILAA NHCs' color can be recovered by reversible thermochromism because of I2 reloading into the ILAA NHCs. When the process is repeated, the temperature can be controlled in a certain range. This alternating light-to-heat conversion significantly improve the effect of PTT. Meanwhile, I2 efficiently acts dual functions of chemotherapy and PTT. Results show that the photothermal depth by ILAA NHCs is 2.1-fold than other common photothermal agents (PTAs), and the irradiated region exhibits a lower surface temperature. In vitro and in vivo experiments both provide ILAA NHCs an excellent comprehensive antitumor effect with synergistic chemo/PTT, indicating versatile potential for tumor chemo/PTT.