Charge Transport through Peptides in Single‐Molecule Electrical Measurements

Abstract

Charge transport across the peptide chains is one of the vital processes in the biological systems, so understanding their charge transport properties is an indispensable prerequisite to explain the complex biochemical phenomenon. Here, we review the charge transport mechanism, the influence of the special groups and the experimental conditions on the charge transport through the peptide backbone by employing the single-molecule electrical measurements. Besides, we further review the recent progresses in charge transport properties of supramolecular interaction among the adjacent peptide chains. Finally, we discuss some experimental and theoretical contradictions existing in the charge transport through peptides and provide new inspiration for the future development of the bioelectronics at the single-molecule scale.Haining Zheng (left) received her BEng Degree from Qingdao University of Science and Technology in 2017. She is currently pursuing her master degree under the supervision of Prof. Wenjing Hong in Xiamen University. Her research interests include the charge transport through peptidesupramolecular interaction network and quantum interference effects of perovskite quantum dots in single-molecule scale.Feng Jiang (middle) received his BEng Degree from Qingdao University of Science and Technology in 2017. He is currently a master student under the supervision of Prof. Wenjing Hong at Xiamen University, where he is interested in the quantum interference effects in singlemolecule electronics.Prof. Wenjing Hong has been a full professor in State Key Laboratory of Physical Chemistry of Solid Surfaces and College of Chemistry and Chemical Engineering in Xiamen University. He obtained a Ph.D. degree in 2013 from the University of Bern, Switzerland under supervision of Prof. Thomas Wandlowski. His current research is mainly focused on single-molecule electronics, the applications of artificial intelligence for chemistry and chemical engineering.

Efficient Intermolecular Charge Transport in π-Stacked Pyridinium Dimers Using Cucurbit[8]uril Supramolecular Complexes

“…Intermolecular charge transport in π-stacked aromatic groups is central to organic electronics and biological processes . In the field of organic electronics, it is widely believed that device efficiency critically depends on interchain charge transport between π-conjugated molecules. − In biology, charge transport through π-stacked DNA base pairs , and aromatic amino acid residues , plays a key role in metabolism, photosynthesis, and oxidative damage and repair of DNA . From this view, understanding intermolecular charge transport through π-stacked molecules is essential for elucidating the fundamental mechanisms behind biological redox processes and for designing new materials for organic electronics.…”

“…22 However, this conclusion was challenged in a subsequent publication in which the formation of 2:2 quaternary complexes between arylviologen and CB [8] was reported. 59 To understand how the synthetic host affects the charge transport properties of stacked pyridinium, we use cucurbit [7]uril (CB [7]), a smaller homologue to CB [8] (Figure 4a−b). CB [7] shows similar binding properties to CB [8] albeit with a smaller portal diameter (5.4 Å) compared to CB[8] (6.9 Å), which allows for the complexation of only one aromatic guest molecule (Figures S48−S55).…”

“…59 To understand how the synthetic host affects the charge transport properties of stacked pyridinium, we use cucurbit [7]uril (CB [7]), a smaller homologue to CB [8] (Figure 4a−b). CB [7] shows similar binding properties to CB [8] albeit with a smaller portal diameter (5.4 Å) compared to CB[8] (6.9 Å), which allows for the complexation of only one aromatic guest molecule (Figures S48−S55). 25,43 Results from STM-BJ experiments on host−guest complexes formed by CB [7] are shown in Figures 4c−e and S56.…”

“…Our results show that π-stacked pyridinium dimers exhibit comparable molecular conductance to isolated, single pyridinium molecules, despite a longer transport pathway and a switch from intra-to intermolecular charge transport. Control experiments using a CB[8] homologue (cucurbit[7]uril, CB [7]) show that the synthetic host primarily serves to facilitate dimer formation and plays a minimal role on molecular conductance. Molecular modeling using density functional theory (DFT) reveals that pyridinium molecules are planarized upon dimerization inside the host cavity, which facilitates charge transport.…”

Conformation-dependent charge transport through short peptides

“…The conductance of single peptides was measured in a mechanically controlled break junction (MCBJ) at fixed distance for recognition purposes 15 and in the STM-BJ as a function of electrode separation. [16][17][18] In the later experiments, the weak effect of the amino-acid composition on the peptide conductance was confirmed. Typically, the analysis only involves the study of the most prominent conductance peak and stretched peptide chains were found to be poor conductors.…”