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 (I-2)-loaded acetylated amylose nanohelix clusters (ILAA NHCs) under the guidance of molecular dynamic simulation in which I-2 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, I-2 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 I-2 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, I-2 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.