Guiding chiral nanoparticle growth

The concept of chirality is a central one in chemistry. Chiral chemicals, in which two structures are mirror images that cannot be superimposed, include amino acids and DNA. But chirality isn’t limited to molecules; chiral structures can exist on larger scales, such as nanoparticles, snail shells, and even galaxies. In the past, scientists have grown chiral nanoparticles using templates, such as DNA or proteins. Now, researchers led by Seoul National University’s Ki Tae Nam and Pohang University of Science & Technology’s Junsuk Rho report that sulfur-containing chiral molecules, such as cysteine or glutathione, can guide the growth of gold nanoparticles into chiral structures (Nature 2018, DOI: 10.1038/s41586-018-0034-1). The sulfur-containing molecules influence the growth rate of crystal facets within the gold, ultimately producing helicoid twists in the nanoparticles’ structures. The resulting particles are similar in size and can rotate polarized light. The researchers think the strategy could be used to make chiral nanoparticles for various applications, including plasmonic metamaterials, which have exotic optical properties and may be useful for sensing and imaging.