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Less invasive and more effective cancer treatments have been the aim of research in recent decades, e.g. photothermal tumour ablation using gold nanorods. In this study we investigate the cell death pathways activated, and confirm the possibility of CTAB-coated nanoparticle use in vivo. Nanorods were synthesized by the seeding method; some of them were centrifuged and washed to eliminate soluble CTAB. The MTT cytotoxicity test was performed to evaluate cytotoxicity, and the particles' viability after their synthesis was assessed. Once it had been observed that centrifuged and washed nanorods are harmless, and that nanoparticles must be used within 48 h after their synthesis, in vivo hyperthermic treatment was performed. After irradiation, a tumour biopsy was subjected to a chemiluminescence assay to evaluate membrane lipoperoxidation, and to a TRAP assay to evaluate total antioxidant capacity. There was a 47 °C rise in temperature observed at the tumour site. Animals irradiated with a laser (with or without nanorods) showed similar membrane lipoperoxidation, more intense than in control animals. The antioxidant capacity of experimental animal tumours was elevated. Our results indicate that necrosis is possibly the cell death pathway activated in this case, and that nanorod treatment is worthwhile. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]