Internal temperature increase during photothermal tumour ablation in mice using gold nanorods

Laser ablation (LA) is gaining large acceptance in the treatment of tumor. One of the main risks of this treatment is damaging the healthy tissue around the tumor. Among the solutions proposed to improve the selectivity of the LA and to localize heating to tumor tissue, the use of gold nanoparticles is one of the most promising. The aim of this work is threefold: i) to measure the temperature increase within the tumor during plasmonic photothermal therapy using gold nanorods; ii) to investigate the influence of nanorods concentration and laser settings on both the intra-tumoral temperature and the tumor surface temperature; iii) and to establish the nanorods concentrations able to cause tumor resorption at a defined laser settings. Two sets of trials were performed: i) 16 mice were divided in four groups with different treatment time (i.e., 5 min, 2min, 1min, and 30s), with constant gold nanorods amount (i.e., 12.5μg) and laser power (i.e., 3W·cm-2); ii) 16 mice were divided in four groups treated with different amount of gold nanorods (i.e., control, 12.5μg, 25μg, 50μg) for 5 min at 2W·cm-2. Results show significant differences between internal and surface temperatures. We also demonstrate that this temperature difference increases with nanoparticle concentrations, decreases with laser power, and is not influenced by treatment time. This information is critical to improve the theoretical models that will guide future study designs in sensitive orthotopic tumor models.