Bio-inspired molecular electronics

Electron transfer in proteins can occur over long molecular distances to facilitate a number of crucial biological processes, including respiration and photosynthesis. A fundamental understanding of electron transfer in proteins is not only central to the elucidation of these essential biological processes in living organisms, but also to the design and development of bio-inspired molecular electronic components. Much research has been conducted on charge transfer in proteins, including azurin and the mitochondrial electron carrier, cytochrome C. However, in light of the complexity of such systems, synthetic model peptides present as excellent alternatives. Such peptides can adopt specific secondary structures, for instance helices and β-strands through diligent design, to allow the study of electron transfer in a somewhat more controlled setting. Furthermore, specific functionalization of their backbone enables precision-branching, a key feature of three-dimensional molecular circuitry. While molecular electronics provides an opportunity to begin to redefine integrated circuit technologies, one must first understand and subsequently be able to predict and control the associated charge transfer kinetics and dynamics before this vision can be realized.

To address these questions, we use a combination of theory and experiment to advance a fundamental understanding of electron transport in naturally occurring peptides, while exploiting their electronic properties to promote the design and development of functional bio-inspired molecular electronic devices. A bottom-up approach for the fabrication of components for the electronics industry will be required in the not too distant future, with the combination of solid-state techniques used here closely aligning to future device development.

Biological applications of nanomaterials

A case study: Photoswitchable Peptide-Modified Nanoporous Anodic Alumina for On-Demand Molecular Transport

The controlled transport of molecules across membranes is central to nature (e.g., in protein channels and ion pumps) but also to many highly valuable applications such as desalination, on-demand drug delivery, chromatography, and others. Artificial nanoporous membranes, for example nanoporous anodic alumina membranes (NAAMs), provide an important tool for studying the mechanisms and dynamics associated with molecular transporting across a membrane.

Here, an alternative approach to overcome the inherent limitations of polymer-based stimuli-responsive membranes, while providing the practical and functional requirements for selective on-demand molecular transport applications, are synthetic nanoporous membranes modified with optically switchable molecules (PSP-NAAMs). The results showed that the molecular transport across PSP-NAAMs could be repeatedly switched between on and off state, which is highly significant for on-demand triggered drug release systems.