Layer-by-layer assembly of photonic crystal using DNA

Photonic crystals are a key component for optical next-generation communication and computing in that they have a periodic 3D structure on the same scale as optical wavelengths. The major difficulty in the practical use of photonic crystals exists in its fabrication process. As an optical component, it must be a defect-free large crystal with waveguide patterns affecting the propagation of photons. Many attempts have been made to realize such a crystal, but low-cost and rapid fabrication of a defect-free large crystal is still a difficult problem. Here, we propose a novel fabrication method combining colloidal crystallization and DNA nanotechnology. In this method, a face-centered lattice made of 1-μm polystyrene particles is assembled on a patterned template in a layer-by-layer fashion. In order to control the binding among particles, DNA-gold nano-particle conjugates (10-nm GNP modified with 52mer DNA) are used. Specific bonding rules between particles and GNPs defined by the base sequence of DNA results in the layer-by-layer growth of the crystal. We have built two-layer crystals using the proposed method, and the results show its feasibility. We also found some important factors necessary to improve the quality of the crystal.