Tag Archives: John Horsley

Peptides as bio-inspired electronic materials

7 September 2018:

A new paper with CNBP authors Jingxian Yu, John Horsley and Andrew Abell extends fundamental knowledge of charge transfer dynamics and kinetics in peptides and also open up new avenues to design and develop functional bio-inspired electronic devices, such as on/off switches and quantum interferometers, for practical applications in molecular electronics.

Journal: Accounts of Chemical Research.

Publication title: Peptides as Bio-Inspired Electronic Materials: An Electrochemical and First-Principles Perspective.

Authors: Jingxian Yu, John R. Horsley, and Andrew D. Abell.

Abstract: Molecular electronics is at the forefront of interdisciplinary research, offering a significant extension of the capabilities of conventional silicon-based technology as well as providing a possible stand-alone alternative. Bio-inspired molecular electronics is a particularly intriguing paradigm, as charge transfer in proteins/peptides, for example, plays a critical role in the energy storage and conversion processes for all living organisms. However, the structure and conformation of even the simplest protein is extremely complex, and therefore, synthetic model peptides comprising well-defined geometry and predetermined functionality are ideal platforms to mimic nature for the elucidation of fundamental biological processes while also enhancing the design and development of single-peptide electronic components.

In this Account, we first present intramolecular electron transfer within two synthetic peptides, one with a well-defined helical conformation and the other with a random geometry, using electrochemical techniques and computational simulations. This study reveals two definitive electron transfer pathways (mechanisms), the natures of which are dependent on secondary structure. Following on from this, electron transfer within a series of well-defined helical peptides, constrained by either Huisgen cycloaddition, ring-closing metathesis, or a lactam bridge, was determined. The electrochemical results indicate that each constrained peptide, in contrast to a linear counterpart, exhibits a remarkable shift of the formal potential to the positive (>460 mV) and a significant reduction of the electron transfer rate constant (up to 15-fold), which represent two distinct electronic “on/off” states. High-level calculations demonstrate that the additional backbone rigidity provided by the side-bridge constraints leads to an increased reorganization energy barrier, which impedes the vibrational fluctuations necessary for efficient intramolecular electron transfer through the peptide backbone. Further calculations reveal a clear mechanistic transition from hopping to superexchange (tunneling) stemming from side-bridge gating. We then extended our research to fine-tuning of the electronic properties of peptides through both structural and chemical manipulation, to reveal an interplay between electron-rich side chains and backbone rigidity on electron transfer. Further to this, we explored the possibility that the side-bridge constraints present in our synthetic peptides provide an additional electronic transport pathway, which led to the discovery of two distinct forms of quantum interferometer. The effects of destructive quantum interference appear essentially through both the backbone and an alternative tunneling pathway provided by the side bridge in the constrained β-strand peptide, as evidenced by a correlation between electrochemical measurements and conductance simulations for both linear and constrained β-strand peptides. In contrast, an interplay between quantum interference effects and vibrational fluctuations is revealed in the linear and constrained 310-helical peptides.

A step towards bio-inspired quantum interferometers

Jingxian Yu_low_sq29 November 2016:

CNBP researchers (lead author Jingxian Yu pictured), have published a paper exploring the quantum interference effects on electronic transport in peptides. The work has just been reported in the journal ‘Molecular Systems Design & Engineering’ and is accessible online.

Journal: Molecular Systems Design & Engineering.

Title: Exploiting the interplay of quantum interference and backbone rigidity on electronic transport in peptides: A step towards bio-inspired quantum interferometers.

Authors: Jingxian Yu, John R Horsley and Andrew D Abell.

Abstract: Electron transfer in peptides provides an opportunity to mimic nature for applications in bio-inspired molecular electronics. However, quantum interference effects, which become significant at the molecular level, have yet to be addressed in this context. Electrochemical and theoretical studies are reported on a series of cyclic and linear peptides of both β-strand and helical conformation, to address this shortfall and further realize the potential of peptides in molecular electronics. The introduction of a side-bridge into the peptides provides both additional rigidity to the backbone, and an alternative pathway for electron transport. Electronic transport studies reveal an interplay between quantum interference and vibrational fluctuations. We utilize these findings to demonstrate two distinctive peptide-based quantum interferometers, one exploiting the tunable effects of quantum interference (β-strand) and the other regulating the interplay between the two phenomena (310-helix).

CNBP researchers visit Wuhan

Wuhan12 October 2015:

CNBP researchers from the University of Adelaide, Dr Jingxian Yu and Dr John Horsley, were invited by several academic facilities in Wuhan, China, to disseminate their recent research.

Lectures were given to the School of Chemistry and Chemical Engineering at Huazhong University of Science and Technology (HUST), China University of Geosciences (CUG), and Central China Normal University (CCNU).

A number of ‘flyers’ were circulated defining the role of the CNBP, in the hope of inspiring bright, enthusiastic students and academics alike to consider a move to Australia.

Whilst in Wuhan, they also had the opportunity and pleasure of visiting CNBP partner, Wuhan National Laboratory for Optoelectronics (HUST), and the Key Laboratory of Biomedical Polymers of the Ministry of Education, at Wuhan University.

Networking provided a number of possible future collaborations, including electron transport in single molecules, with Professors Shan Jin and Shenghua Liu (CCNU), and peptide-based nanocarriers for drug delivery, with Prof Xianzheng Zhang (Wuhan University).


PhD commendation

John Horsley Low Res Edit 01417 July 2015:

Congratulations to CNBP researcher John Horsley, who has just been awarded a Dean’s Commendation for Doctoral Thesis Excellence from the University of Adelaide.  A Commendation is awarded when all examiners consider the thesis to be ‘outstanding’.

John’s thesis, titled “The Effects of Macrocyclic Constraints on Electron Transfer in Peptides”, examined the importance of secondary structure characteristics to proteins/peptides, and its relevance to electronic transport.

Currently, John is working on synthesizing a light-driven peptide-based sensor to detect changes in ligand/receptor interactions for the CNBP.


Adelaide node welcomes new research fellows

NeuroFebruary 2015: Welcome:

CNBP Adelaide Node are pleased to welcome new CNBP Research Fellow commencing in January/February 2015.

  • Jenny Butler who is joined the Recognise theme on January 28th
  • Peipei Jia who joined the Measure and Illuminate theme on January 31st
  • Xiaozhou (Michelle) Zhang who joined the Recognise theme on February 9
  • John Horsley who joined the Recognise theme on February 9

Publication – Journal of the American Chemical Society

ThemesSeptember 2014 – Journal of the American Chemical Society

Unraveling the interplay of backbone rigidity and electron rich side-chains on electron transfer in peptides: the realization of tunable molecular wires.

Horsley JR, Yu J, Moore KE, Shapter JG, Abell AD. J Am Chem Soc. 2014 Sep 3; 136(35):12479-88

For the full article please click here