Plasmonic Circular Dichroism of Gold Nanoparticle Based Nanostructures

With great advances in wet chemical synthesis of nanoparticles (NPs), plasmonic NPs with various sizes and morphologies are easily available nowadays and demonstrate great potentials in optical, electronic, and biomedical applications. Plasmonic circular dichroism (CD), relating to circular dichroism responses at localized surface plasmon resonance of metal nanostructures, has emerged as a research direction of plasmonics with promising prospects in enantioselective catalysis, chiral separation, and ultrasensitive detections. Herein, plasmonic CD responses of gold nanoparticle based nanostructures are summarized. Two kinds of plasmonic CD phenomena are investigated: structural CD and induced CD. Structural CD is the response from chiral assemblies composed of plasmonic NPs with strong dipole-dipole interactions. Induced CD is the response of nonchiral plasmonic NPs with chiral molecules attached at surface. The weak CD is the result of Coulomb interaction between chiral molecules and plasmonic NPs. Efforts on how to achieve strong CD signals for these two configurations by using chiral molecules and Au nanoparticles are reported. The fabrication of chiral nanostructures, tuning and amplification of CD responses, CD-based biosensors, chiral catalysis, and future perspectives are presented. The importance of the shape anisotropy of gold nanorods in the generation and amplification of CD signals is especially highlighted.