Chiral Recognition of Self-Assembled Peptides on MoS2 via Lattice Matching.

ABSTRACT

Chiral recognition of peptides on solid surfaces has been studied for a better understanding of their assembly mechanism toward its applications in stereochemistry and enantioselective catalysis. However, moving from small peptides such as dipeptides, understanding the chiral recognition of larger biomolecules such as oligopeptides or peptides with a larger sequence is challenging. Furthermore, their intrinsic mechanism for chiral recognition in liquid conditions was poorly investigated experimentally. Here, we used in/ex situ atomic force microscopy (AFM) to investigate the chiral recognition of self-assembled structures of l/d-type peptides on molybdenum disulfide (MoS2). We chose single-layer MoS2 with a triangular shape as a substrate for the self-assembly of peptides. The facet edges of MoS2 were utilized as a landmark to identify the crystallographic orientation of their ordered structures. We found both peptide enantiomers formed nanowires on MoS2 with a mirror symmetry according to the facet edges of MoS2. From in situ AFM measurements, we found a dimension of a unit cell in the self-assembled structure and proposed a model of lattice matching between peptides and MoS2 lattice. The lattice matching for chiral recognition was further investigated by changing peptide sequences and surface lattice from MoS2 to graphite. This work further deepened the understanding of biomolecular chiral recognition and will lead us to rationally design specific morphologies and conformations of chiral self-assembled structures of peptides with expected functions in the future.