Sub-100 nm hollow Au-Ag alloy urchin-shaped nanostructure with ultrahigh density of nanotips for photothermal cancer therapy.

The 'sea urchin'-like nanostructures with particular small size (<100 nm) and abundant multi-tips have not yet been employed for the cancer photothermal therapy (PTT). Here we report sub-100 nm hollow Au-Ag alloy nanourchins (HAAA-NUs) with ultrahigh density of nanotips synthesized via a facile seed-mediated growth. The HAAA-NUs exhibit a remarkably integrated high-quality photothermal feature including well-defined but tunable surface plasmon resonance peak, strong absorption (2.2 × 10(10) M(-1) cm(-1)) as well as high photothermal conversion efficiency (80.4%) in the near-infrared region. Importantly, the HAAA-NUs demonstrate improved photothermal stability verified via continuous exposition and cyclic irradiation of laser beam. The cell assay, in vitro cell ablation and in vivo breast cancer treatment verify that the HAAA-NUs are superior photothermal agent for photothermal tumor ablation therapy owing to low toxicity and high cell destruction capability.