Seed-Mediated Growth and Advanced Characterization of Chiral Gold Nanorods

The controlled growth of gold nanostructures with complex shapes and reduced symmetry, exemplified by chiral gold nanorods and nanoparticles, is one of the most dynamic fields of nanochemistry. A timely summary of underlying concepts, including growth mechanisms and redefined chirality measures, would further promote this research area. In this perspective, we aim to establish qualitative connections between the chiral shapes and growth conditions, specifically for the seed-mediated synthesis of chiral gold nanorods as a convenient case of chiral morphogenesis. The crystallographic and morphological features of achiral nanorods used as seeds, the experimental conditions during chiral growth, and the symmetry of the chiral inducers, can all be exploited to obtain nanorods with intricate chiral shapes. Chirality characterization (such as electron tomography techniques) and quantification (including chirality measures) emerge as critical aspects to comprehensively explore and understand such structures, enabling optimization of their geometric and optical features. We conclude by discussing relevant challenges to be addressed toward a better controlled synthesis of chiral plasmonic nanostructures. Recent progress in bottom-up wet-chemical synthesis of gold nanoparticles has created remarkable opportunities to produce nanoparticles with well-defined chiral shapes and strong chiroptical activities. This perspective focuses on the seed-mediated synthesis of chiral gold nanorods as a convenient case of chiral morphogenesis. Growth mechanisms, chirality measures, and advanced electron microscopy characterization techniques are discussed, aiming to connect chiral morphologies, growth conditions, and optical behavior. image