Sprecher
Beschreibung
The bottom-up self-assembly of photonic crystals with complex symmetries, such as diamond-type structures, requires molecular building blocks with programmable geometry and directional binding, which is challenging in conventional colloidal systems. [1] The DNA origami technique [2], which allows rational design of complex structures, is a powerful tool for this task. A direct rod-connected cubic diamond structure photonic crystal can be achieved by assembling tetrapod DNA origami structure using single-stranded DNA “sticky ends” stretched out from the four tips of the structure. [3] By carefully designing the pattern of the sticky ends, one can control the rotation between neighboring monomers. A 60° rotation between monomer arms, for example, yields the cubic diamond structures while a rotation by 0° at one of the four arms can lead to hexagonal diamond structures. We designed a system of competing sticky ends in which the neighboring monomers have both the possibility to bind with 60° and 0° rotation. By further tuning parameters such as temperature and salt concentrations during crystallization, we were able to observe stacking of cubic/hexagonal diamond structures (Fig. 1a and b6), as well as the emergence of clathrate -type lattices which has exclusively 0° rotation between all monomers (Fig. 1c).
Our clathrate lattice has a lattice constant of 440 nm with 136 monomers forming the unit cell. This spacing leads to the occurrence of structural color in the visible range after stabilizing the DNA origami lattice with an SiO2 coating through a sol-gel process. [4] Upon drying, the resulting structures exhibit blue or green reflections under dark-field illumination, depending on the orientation of the individual crystals and the angle of the incoming light. [5]
References:
[1] He, Mingxin, et al. "Colloidal diamond." Nature 585.7826 (2020): 524-529.
[2] Rothemund, Paul WK. "Folding DNA to create nanoscale shapes and patterns." Nature 440.7082 (2006): 297-302.
[3] Posnjak, Gregor, et al. "Diamond-lattice photonic crystals assembled from DNA origami." Science 384.6697 (2024): 781-785.
[4] Nguyen, Linh, et al. "DNA‐origami‐templated silica growth by sol–gel chemistry." Angewandte Chemie International Edition 58.3 (2019): 912-916.
[5] Yin, X, et al. in preparation.
