A Natural Route to Nanowires and Energy Storage

Organic electronics is a burgeoning area, with a growing range of applications. This new research – in which nanowires are grown naturally rather then synthesized chemically – may provide new methods for biologically-produced or biologically-inspired materials for sustainable nanomanufacturing. Pilin nanofilaments (pili) — known now as microbial nanowires — are a class of fibrous proteins found in the sediment bacteria Geobacter. Temperature studies find metallic characteristics. The conductivity can be modulated by doping or by using an applied voltage in an electrochemical transistor configuration, showing the potential for device applications, including supercapacitors for energy storage

Going the Distance: Long-Range Conductivity in Protein and Peptide Bioelectronic Materials.

Bioelectronic materials interface biomolecules, cells, organs, or organisms with electronic devices, and they represent an active and growing field of materials research. Protein and peptide nanostructures are ideal bioelectronic materials. They possess many of the properties required for biocompatibility across scales from enzymatic to organismal interfaces, and recent examples of supramolecular protein and peptide nanostructures exhibit impressive electronic properties. The ability of such natural and synthetic protein and peptide materials to conduct electricity over micrometer to centimeter length scales, however, is not readily understood from a conventional view of their amino acid building blocks. Distinct in structure and properties from solid-state inorganic and synthetic organic metals and semiconductors, supramolecular conductive proteins and peptides require careful theoretical treatment and experimental characterization methods to understand their electronic structure. In this review, we discuss theory and experimental evidence from recent literature describing the long-range conduction of electronic charge in protein and peptide materials. Electron transfer across proteins has been studied extensively, but application of models for such short-range charge transport to longer distances relevant to bioelectronic materials are less well-understood. Implementation of electronic band structure and electron transfer formulations in extended biomolecular systems will be covered in the context of recent materials discoveries and efforts at characterization of electronic transport mechanisms