Amino Acid-Mediated Preparation of Highly Dendritic Chiral Plasmonic Nanoparticles for SERS-Based Enantiomer Recognition

Chiral plasmonic nanoparticles (CPNPs) are blooming building blocks in modern nanotechnology and have attracted great attention due to their unique capabilities in manipulating light, enabling enantiomeric-based theranostics, realizing chiral sensing, and so on. Here, we report a strategy for the preparation of highly dendritic CPNPs. Using gold nanotriangles as seeds and cysteine as a shape-directing agent, two distinct dendritic nanostructures, termed gold nanoflowers (Au NFs) and gold nanourchins (Au NUs), can be obtained by adjusting the cysteine concentration within the reaction system. Electron microscopy studies show that such dendritic nanoparticles are formed through the island growth mode of Au atoms around the gold nanotriangle seeds. Particularly, they both show capabilities of enantiomer recognition when serving as SERS substrates in the detection of phenylalanine enantiomers, with Au NFs possessing a stronger differentiation ability. This SERS-based enantiomer recognition is also applicable to other chiral molecules (i.e., propranolol), suggesting great potentials of dendritic CPNPs in chiral detection and enantiomer recognition.