Tubelike Gold Sphere-Attapulgite Nanocomposites with a High Photothermal Conversion Ability in the Near-Infrared Region for Enhanced Cancer Photothermal Therapy

Near-infrared (NIR)-induced photothermal therapy (PTT) is now considered to be a promising and highly efficient method for tumor therapy. Photothermal agents play a crucial role in PTT, and they are required to possess the ability to harvest NIR light and transform the photon energy into heat energy. This work reports a facile method to synthesize a new PTT agent, which is based on the electrostatic binding of the Au nanospheres (Au NSs, similar to 15 nm) to the surface of a nanometer-sized mineral, attapulgite, to form tubelike Au-attapulgite nanocomposites. These nano-composites consist of numerous Au NSs, which are linked to each other along the attapulgite surface. The nanocomposites exhibit similar localized surface plasmon resonance absorption characteristics to those of Au nanorods with a longitudinal absorption mode that shifts to the NIR region (similar to 670 nm). Moreover, the nanocomposites have a high C-abs/C-sca ratio (cross section of absorption to scattering) and photothermal conversion efficiency of 25.6%. Their photothermal therapy effect is studied using A549 cells and A549 cell-bearing nude mice as examples. The results indicate that the nanocomposites can be effectively taken up by the cells, and the nanocomposites show good biocompatibility. The A549 cells almost died after they were incubated with the nanocomposites (at 100 mu g mL(-1)) for 12 h and irradiated by an 808 nm laser with a power density of 0.5 W cm(-2) for 15 min. The tumors of nude mice can also be effectively ablated without regrowth during the period of observation (at least 10 d) after photothermal therapy.