Biochemical and histological effects of different light doses on hyperthermic therapy with gold nanorods

Efforts have been made to develop new treatments for cancer with fewer side effects and with a better outcome. Gold nanorods are promising as a cancer treatment device when activated by a light source, usually in near-infrared region. In this study we investigated the effect of different light doses applied to tumors containing gold nanorods and characterized the damage of the treatment in different intracellular locations. The gold nanorods were synthesized by a seed-mediated method and the soluble CTAB was eliminated from the nanorods solution, which was administered to Ehrlich tumor-bearing mice. The nanorods were activated on the tumor tissue by two doses of near-infrared light, either 216 or 600 J cm-2. After the irradiation, the tumors were collected and subjected to biochemical tests to investigate oxidative stress on cell membranes and to evaluate the total antioxidant capacity of cells, or they underwent histological procedures. Results show that the laser itself is responsible for membrane oxidative damage, regardless the presence of gold nanorods, but the nanoparticles are important to oxidative stress generation inside the cells. The intensity of histological damage is directly dependent on the light dose applied. These results are important to better understand how photothermal tumor ablation using gold nanorods occurs.