Control over the emerging chirality in supramolecular gels and solutions by chiral microvortices in milliseconds

Jiashu Sun,Baoquan Ding,Minghua Liu,Pengfei Duan,Fei Tian,Yutao Sang,Xinghua Shi,Qiang Feng,Chao Liu,Fusheng Yan,Li Zhang,Yike Li

doi:10.1038/s41467-018-05017-7

Abstract

The origin of homochirality in life is a fundamental mystery. Symmetry breaking and subsequent amplification of chiral bias are regarded as one of the underlying mechanisms. However, the selection and control of initial chiral bias in a spontaneous mirror symmetry breaking process remains a great challenge. Here we show experimental evidences that laminar chiral microvortices generated within asymmetric microchambers can lead to a hydrodynamic selection of initial chiral bias of supramolecular systems composed of exclusively achiral molecules within milliseconds. The self-assembled nuclei with the chirality sign affected by the shear force of enantiomorphic microvortices are subsequently amplified into almost absolutely chirality-controlled supramolecular gels or nanotubes. In contrast, turbulent vortices in stirring cuvettes fail to select the chirality of supramolecular gels. This study reveals that a laminar chiral microflow can induce enantioselection far from equilibrium, and provides an insight on the origin of natural homochirality.

Highlights

The origin of homochirality in life is a fundamental mystery
Some achiral molecules can evolve in size, complexity, and function through self-assembly into chiral supramolecular systems by spontaneous mirror symmetry breaking[4,5,6,7,8,9]
Symmetry breaking of achiral molecules in the self-assembly process could be biased by purely physical fields, such as hydrodynamic flow by stirring[13,14,15,16,17,18,19,20], circularly polarized light irradiation[21,22,23,24,25], or the combination of hydrodynamic, magnetic, thermal, or light factors[9, 26,27,28,29,30]

Summary

Introduction

The origin of homochirality in life is a fundamental mystery. Symmetry breaking and subsequent amplification of chiral bias are regarded as one of the underlying mechanisms. The velocity of flow near the vents could reach several meters per second, and there is a large change to create high-speed microvortices (length scale from tens to hundreds of micrometers) up to 104 rpm for flows over rock micropores[36] These microvortices may provoke the aggregation of concentrated molecules under non-equilibrium conditions, a. Enlightened by natural rock micropores, we design a microfluidic device to induce counter-rotating laminar chiral microvortices (CW and CCW) inside opposing microchambers, to control over the supramolecular chirality of assemblies either in gels or solutions, exclusively from achiral molecules. The high magnitude of the shear gradient in laminar microvortices allows the alignment and twist of the supramolecular nuclei against the Brownian regime within milliseconds when mirror symmetry breaking occurs These nuclei with a certain chiral bias correlated with the rotation sense of microvortices are subsequently amplified into supramolecular aggregates with nearly absolute chirality

Methods

Results

Conclusion