Systematic Adjustment of Pitch and Particle Dimensions within a Family of Chiral Plasmonic Gold Nanoparticle Single Helices.

Systematically controlling the assembly architecture within a class of chiral nanoparticle superstructures is important for fine-tuning their chiroptical properties. Here, we report a family of chiral gold nanoparticle single helices, varying in helical pitch and nanoparticle dimensions, that is assembled using a series of peptide conjugate molecules Cx -(PEPAu M-ox )2 (PEPAu M-ox = AYSSGAPPMox PPF; x = 16-22). We demonstrate that the aliphatic tail length (i) can be used as a handle to systematically tune the helical pitch from 80 to 130 nm; and (ii) influences the size, shape, and aspect ratio of the component nanoparticles. Certain members of this family of materials exhibit intense plasmonic chiroptical activity. These studies highlight the multiple levels of structural control that can be achieved within a class of chiral nanoparticle superstructures via careful design and selection of peptide conjugate precursor.