Nanorattles are nanosized objects made of one or several core particles surrounded by a shell, providing a void between the two constituents. These materials were investigated in the two first funding phases of the NCCR in the context of mechanically-triggered drug delivery. In Phase 3, this project will investigate the assembly of nanorattles into various structures mediated by surface functional groups such as single-stranded DNA. The goal is to study the optical properties of the resulting assemblies, which are expected to mimic opals. The order provided by the assembly of nanorattle shells and within the cores will be tuned separately, and the effect of these two superimposed orders will be investigated to understand how they influence the optical, mechanical and acoustic properties.