Near-Infrared-Responsive Choline-Calix[4]arene-Gold Nanostructures for Potential Photothermal Cancer Treatment

The development of novel chemical approaches for the fabrication of gold nanostructures with localized surface plasmon resonance (LSPR) falling in the near-infrared (NIR) region is one challenging topic in nanomaterials science. Due to their optical and photothermal properties triggered by light excitation in the therapeutic window (Amax = 650-1300 nm), gold-based nanostructures are appealing candidates in anticancer nanomedicine. Here, we report a novel method to prepare waterdispersible gold nanostructures with NIR-LSPR (Amax = 600-1000 nm) properties. The gold nanostructures were achieved in a single step by an unconventional method using NADH as a reducing agent and an amphiphilic choline-calix[4]arene derivative (CholCalix) forming micelles as a template. The CholCalix-Au nanostructures were characterized by UV-visible spectrophotometry, Raman spectroscopy, and atomic force microscopy. Agglomeration of the nanostructures due to multiple crosslinking interactions was observed and supported by modeling simulation. Effective anticancer photothermal-induced effect of the CholCalix-AuNPs was demonstrated on human breast cancer cells irradiated with biofriendly light at 808 nm.