Researchers at Hanyang University recently developed a three-dimensional (3D) microarray with dynamic chirality selection.
Chirality is a non-superimposable structural property; For example, the left hand looks like the right hand in a mirror, but the left hand cannot be superimposed on the right. Chiral structures have been studied in the biochemical field as part of the search for drugs that bind to DNA proteins. The engineering of chiral structures has been attempted for functionality from chiral selectivity; however, it is difficult to fully dynamically switch chirality.
A corolla-inspired study published in ACS nano, is the first to demonstrate the on-demand and dynamically controlled chiral selectivity of a 3D microstructure. The researchers were inspired by the chirality of the corolla, so often seen in nature. Flowers like the Mandevilla protect themselves from strong winds by the chirality of their five-petalled corolla. This chiral crown uses a counter-clockwise direction with asymmetrically shaped petals. Alternatively, flowers like Phlox subulata have no chirality as this five-petalled corolla is superimposed on its mirror image with symmetrically shaped petals. This is called achirality.
In the corolla-inspired 3D microstructure, five semi-cylindrical micropillars are arranged radially to mimic a natural flower composed of five petals. This microarray is an achiral structure due to its symmetrically shaped semi-cylindrical microcolumns. A key point of this work is that this achirality of the microarray can then dynamically disappear by twisting the microcolumns, which transforms its symmetric shape into an asymmetric one.
The microcolumns are made of easily deformable rubbery polydimethylsiloxane and magnetic iron particles; therefore, when a magnetic field is applied, the pillar tops twist while the pillar bases remain attached to the substrate of microarrays. When the twisting movements begin, the microarray does not overlap with its mirror image.
Consequently, the achirality of the microarray changes in real time to counterclockwise or clockwise chirality by clockwise or counterclockwise twisting actions, respectively. Microcolumns in an array simultaneously twist clockwise, resulting in counterclockwise chirality. Conversely, clockwise chirality is led by microcolumns simultaneously rotating counterclockwise.
The researchers in the study emphasize a key aspect of this technique, as by simply regulating the direction of magnetic fields, chiralities of the microarrays can be dynamically converted from a counterclockwise to a clockwise direction and vice versa.
This chiral-selective three-dimensional microstructure has potential applications in optical device design. Typically, electromagnetic light waves are circularly polarized, separated into right-hand or left-hand circularly polarized light, and interact with the chirality of the structure.
Through this chiral-selective interaction, the polarization direction of any light could be detected when light enters the chiral microarray. Right or left circularly polarized light selectively interacts with the counterclockwise or clockwise chirality of the corolla-like microarray.
Jeong Eun Park et al, On-Demand Dynamic Chirality Selection in Flower Corolla-like Microcolumn Arrays, ACS nano (2022). DOI: 10.1021/acsnano.2c04825
Provided by Hanyang University
Quote: Three-dimensional flower corollas with on-demand chiral selectivity (2022, November 23), retrieved November 23, 2022 from https://phys.org/news/2022-11-three-dimensional-corollas-on-demand -chiral.html
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