Synthesis of chiral gold helicoid nanoparticles using glutathione.

Chiral plasmonic nanostructures are in high demand because of their unique optical properties, which are applicable to polarization control, chiral sensing and biomedical applications. An easy and scalable synthesis method for these nanostructures may facilitate their development further. We have reported the synthesis for 432-symmetric chiral plasmonic nanoparticles by using a seed-mediated colloidal method facilitated by a chiral amino acid and peptides. Among those, 432 helicoid III nanoparticles particularly exhibited well-defined chiral morphologies and exceptional chiroptic properties, evidenced by a Kuhn's dissymmetry factor (g-factor) of 0.2, making them valuable for various applications. Here, we detail the synthesis stages, including the synthesis of seed nanoparticles, the verification of each stage outcome and the calibration of synthesis conditions. We further illustrate the troubleshooting section and video-document the stages to facilitate the reliable reproduction of 432 helicoid III nanoparticles. The procedure requires 8 h to complete and can be carried out by users with expertise in chemistry or materials science.