Single-Molecule Protein Electronics

Dear Colleagues,

If proteins can be formed into robust electronic devices, the technological possibilities are endless:  Molecular scale devices capable of exquisite sensing and chemical processing with electronic feedback offer a new approach to interfacing silicon and biology. Long range electronic transport by proteinaceous material does occur;  this is clear in the remarkable performance of Cable Bacteria. These visible (to the naked eye) bacterial filaments span a centimeter-scale gap between the red and black soil layers that give direct evidence of the electrochemistry carried out by the electrons transported by filaments. However, the field is far from yielding a practical technology. The goal of this issue is to bring together leading experimentalists and theorists working in this field of protein electronics with the goal of better defining the key challenges.

 There are unresolved disputes among theorists. Here are a few of which I am aware:

• Is the transport quantum coherent, somehow surviving environmental fluctuations over relatively long distances?
• Is it hopping transport? And if so, how can this be possible given the large reorganization energies indicated by electrochemical data?
• Is the transport indeed electronic or do ions contribute? Does proton-coupled motion play a role?

The experimental landscape is no less foggy. Some examples I can point to are the following:

• Many scanning tunneling microscope experiments have reported nS conductances over many nm distances. Yet some of the same proteins have only been shown to conduct in conducting AFM experiments after forces of many nN were applied.
• Conducting bacterial filaments have been reported as showing significant conductances over micron distances in some labs but not in others.

The state of the field reminds me of the state of surface science before the introduction of the ConFlat flange yielded atomically-clean surfaces.  Clean surface science then led to the field-effect transistor and all that CMOS has delivered.  Breakthroughs that allowed proteins to be wired directly into electronic circuits would bring about similar revolutionary changes. Imaging a CMOS wafer on which millions of polymerase molecules reported DNA sequences electronically at their natural enzymatic processing rate. It is my hope that this issue helps to define some of the challenges of the future field of robust protein electronics.

Prof. Dr. Stuart Lindsay
Dr. Bintian Zhang
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Biomolecules is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.