Artificially constructed materials can be designed to shape the propagation of light and can thus exhibit optical characteristics that are not found in nature. With such metamaterials, remarkable optical applications such as cloaking of objects, sensing of molecular environments or the fabrication of perfect lenses that are not bound by optical resolution limits could be realised. However, for metamaterials to operate at visible wavelengths they have to be structured in three dimensions with nanometre precision which currently poses an enormous barrier to their fabrication. By using molecular self-assembly based on the self-recognizing properties of sequence-programmable DNA strands, this barrier will be overcome. After having pioneered the 3D DNA origami method and the creation of DNA-based metamaterials, I propose the following new paths of research:i) Metamaterials that are switchable in electric or magnetic fields and operate at visible or near infrared wavelengths will be designed and produced by DNA self-assembly for the first time. The hypothesis that materials with strong chirality show negative refraction will be tested and optical resonators with dimensions below 100 nm will be generated.ii) The light-shaping characteristics of metal particle helices will be used to detect organic molecules. As most organic molecules are chiral and can be considered as chiral arrangements of multiple dipole elements, it is expected that the organic dipoles couple to the plasmonic dipoles of the metal helices. This in turn will induce changes in the optical activity of the material. In a parallel approach, organic molecules will be used to induce conformational changes in DNA-supported particle assemblies, which will then be detected in their optical response. Both of these fundamentally new detection schemes will allow extremely sensitive detection of biomolecules at visible wavelengths.