Synthesis of degradable titanium disulfide nanoplates for photothermal ablation of tumors

Abstract

Inorganic nanomaterials with high photothermal effects have received immense interest for photothermal therapy of tumors, while most of them suffer from long-term safety concerns due to their non-degradability. To address this issue, we have reported the PEGylated titanium disulfide (TiS2-PEG) nanoplates as degradable photothermal agents. The oleylamine-capped TiS2 nanoplates with an average size of ∼200 nm have been prepared via a high-temperature liquid-phase route, and they can be easily dispersed in nonpolar solvents and remain high stability for at least one month. To confer hydrophilicity, the oleylamine-capped TiS2 nanoplates are then surface-modified with amphiphilic PEGylated lipids through Van der Waals interactions. When dispersed in saline solution at 37 °C, the TiS2-PEG are unstable and they can be gradually decomposed into Ti(OH)4/TiO2 sol ultrasmall particles (<5 nm) within 72 h, indicating the suitable degradable feature. In addition, the TiS2-PEG nanoplates exhibit a strong near-infrared photoabsorption with a high photothermal conversion efficacy of 36.3% upon 808 nm laser irradiation. The in vitro and in vivo experiments confirm the low cytotoxicity of TiS2-PEG and high photothermal ablation ability towards cancer cells by the combination of TiS2-PEG and 808 nm laser. Importantly, owing to the degradability and size reduction, part of TiS2-PEG can be excreted from mice bodies via urine and feces, thus alleviating safety concerns. Therefore, the present TiS2-PEG nanoplates can act as a safe and degradable photothermal agent for tumor therapy, which also provides some insights into developing other degradable inorganic nanoagents.

Keywords

• Titanium disulfide
• Degradability
• Photothermal therapy
• Tumor