@article {3064, title = {Solvent-Induced Assembly of Microbial Protein Nanowires into Superstructured Bundles.}, journal = {Biomacromolecules}, volume = {22}, year = {2021}, month = {2021 Mar 08}, pages = {1305-1311}, abstract = {

Protein-based electronic biomaterials represent an attractive alternative to traditional metallic and semiconductor materials due to their environmentally benign production and purification. However, major challenges hindering further development of these materials include (1) limitations associated with processing proteins in organic solvents and (2) difficulties in forming higher-order structures or scaffolds with multilength scale control. This paper addresses both challenges, resulting in the formation of one-dimensional bundles composed of electrically conductive protein nanowires harvested from the microbes and . Processing these bionanowires from common organic solvents, such as hexane, cyclohexane, and DMF, enabled the production of multilength scale structures composed of distinctly visible pili. Transmission electron microscopy revealed striking images of bundled protein nanowires up to 10 μm in length and with widths ranging from 50-500 nm (representing assembly of tens to hundreds of nanowires). Conductive atomic force microscopy confirmed the presence of an appreciable nanowire conductivity in their bundled state. These results greatly expand the possibilities for fabricating a diverse array of protein nanowire-based electronic device architectures.

}, keywords = {Electric Conductivity, Electron Transport, Geobacter, Nanowires, Solvents}, issn = {1526-4602}, doi = {10.1021/acs.biomac.0c01790}, author = {Sun, Yun-Lu and Montz, Brian J and Selhorst, Ryan and Tang, Hai-Yan and Zhu, Jiaxin and Nevin, Kelly P and Woodard, Trevor L and Ribbe, Alexander E and Russell, Thomas P and Nonnenmann, Stephen S and Lovley, Derek R and Emrick, Todd} } @article {3070, title = {An Chassis for Production of Electrically Conductive Protein Nanowires.}, journal = {ACS Synth Biol}, volume = {9}, year = {2020}, month = {2020 Mar 20}, pages = {647-654}, abstract = {

pilin-based electrically conductive protein nanowires (e-PNs) are a revolutionary electronic material. They offer novel options for electronic sensing applications and have the remarkable ability to harvest electrical energy from atmospheric humidity. However, technical constraints limit mass cultivation and genetic manipulation of . Therefore, we designed a strain of to express e-PNs by introducing a plasmid that contained an inducible operon with genes for type IV pili biogenesis machinery and a synthetic gene designed to yield a peptide monomer that could be assembled into e-PNs. The e-PNs expressed in and harvested with a simple filtration method had the same diameter (3 nm) and conductance as e-PNs expressed in . These results, coupled with the robustness of for mass cultivation and the extensive toolbox for genetic manipulation, greatly expand the opportunities for large-scale fabrication of novel e-PNs.

}, keywords = {Electric Conductivity, Escherichia coli, Fimbriae Proteins, Fimbriae, Bacterial, Geobacter, Graphite, Microorganisms, Genetically-Modified, Microscopy, Atomic Force, Nanowires, Operon, Protein Engineering}, issn = {2161-5063}, doi = {10.1021/acssynbio.9b00506}, author = {Ueki, Toshiyuki and Walker, David J F and Woodard, Trevor L and Nevin, Kelly P and Nonnenmann, Stephen S and Lovley, Derek R} } @article {3075, title = {Decorating the Outer Surface of Microbially Produced Protein Nanowires with Peptides.}, journal = {ACS Synth Biol}, volume = {8}, year = {2019}, month = {2019 Aug 16}, pages = {1809-1817}, abstract = {

The potential applications of electrically conductive protein nanowires (e-PNs) harvested from might be greatly expanded if the outer surface of the wires could be modified to confer novel sensing capabilities or to enhance binding to other materials. We developed a simple strategy for functionalizing e-PNs with surface-exposed peptides. The gene for the monomer that assembles into e-PNs was modified to add peptide tags at the carboxyl terminus of the monomer. Strains of were constructed that fabricated synthetic e-PNs with a six-histidine "His-tag" or both the His-tag and a nine-peptide "HA-tag" exposed on the outer surface. Addition of the peptide tags did not diminish e-PN conductivity. The abundance of HA-tag in e-PNs was controlled by placing expression of the gene for the synthetic monomer with the HA-tag under transcriptional regulation. These studies suggest broad possibilities for tailoring e-PN properties for diverse applications.

}, keywords = {Carboxy-Lyases, Ethylene Glycols, Molecular Structure, Nanowires, Oxygenases, Peptides, Phenylalanine Ammonia-Lyase, Plasmids, Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Styrenes}, issn = {2161-5063}, doi = {10.1021/acssynbio.9b00131}, author = {Ueki, Toshiyuki and Walker, David J F and Tremblay, Pier-Luc and Nevin, Kelly P and Ward, Joy E and Woodard, Trevor L and Nonnenmann, Stephen S and Lovley, Derek R} } @article {3081, title = {Conductive Composite Materials Fabricated from Microbially Produced Protein Nanowires.}, journal = {Small}, volume = {14}, year = {2018}, month = {2018 Nov}, pages = {e1802624}, abstract = {

Protein-based electronic materials have numerous potential advantages with respect to sustainability and biocompatibility over electronic materials that are synthesized using harsh chemical processes and/or which contain toxic components. The microorganism Geobacter sulfurreducens synthesizes electrically conductive protein nanowires (e-PNs) with high aspect ratios (3 nm {\texttimes} 10-30 {\textmu}m) from renewable organic feedstocks. Here, the integration of G. Sulfurreducens e-PNs into poly(vinyl alcohol) (PVA) as a host polymer matrix is described. The resultant e-PN/PVA composites exhibit conductivities comparable to PVA-based composites containing synthetic nanowires. The relationship between e-PN density and conductivity of the resultant composites is consistent with percolation theory. These e-PNs confer conductivity to the composites even under extreme conditions, with the highest conductivities achieved from materials prepared at pH 1.5 and temperatures greater than 100 {\textdegree}C. These results demonstrate that e-PNs represent viable and sustainable nanowire compositions for the fabrication of electrically conductive composite materials.

}, keywords = {Geobacter, Nanocomposites, Nanowires, Polymers}, issn = {1613-6829}, doi = {10.1002/smll.201802624}, author = {Sun, Yun-Lu and Tang, Hai-Yan and Ribbe, Alexander and Duzhko, Volodimyr and Woodard, Trevor L and Ward, Joy E and Bai, Ying and Nevin, Kelly P and Nonnenmann, Stephen S and Russell, Thomas and Emrick, Todd and Lovley, Derek R} } @article {3101, title = {Synthetic Biological Protein Nanowires with High Conductivity.}, journal = {Small}, volume = {12}, year = {2016}, month = {2016 Sep}, pages = {4481-5}, abstract = {

Genetic modification to add tryptophan to PilA, the monomer for the electrically conductive pili of Geobacter sulfurreducens, yields conductive protein filaments 2000-fold more conductive than the wild-type pili while cutting the diameter in half to 1.5 nm.

}, keywords = {Amino Acid Sequence, Electric Conductivity, Fimbriae, Bacterial, Geobacter, Nanowires, Proteins, Tryptophan}, issn = {1613-6829}, doi = {10.1002/smll.201601112}, author = {Tan, Yang and Adhikari, Ramesh Y and Malvankar, Nikhil S and Pi, Shuang and Ward, Joy E and Woodard, Trevor L and Nevin, Kelly P and Xia, Qiangfei and Tuominen, Mark T and Lovley, Derek R} } @article {514, title = {Biofilm and nanowire production leads to increased current in Geobacter sulfurreducens fuel cells.}, journal = {Appl Environ Microbiol}, volume = {72}, year = {2006}, month = {2006 Nov}, pages = {7345-8}, abstract = {Geobacter sulfurreducens developed highly structured, multilayer biofilms on the anode surface of a microbial fuel cell converting acetate to electricity. Cells at a distance from the anode remained viable, and there was no decrease in the efficiency of current production as the thickness of the biofilm increased. Genetic studies demonstrated that efficient electron transfer through the biofilm required the presence of electrically conductive pili. These pili may represent an electronic network permeating the biofilm that can promote long-range electrical transfer in an energy-efficient manner, increasing electricity production more than 10-fold.}, keywords = {Acetates, Bioelectric Energy Sources, Biofilms, Electricity, Electrodes, Electron Transport, Fimbriae, Bacterial, Geobacter, Microscopy, Confocal, Mutation, Nanowires}, issn = {0099-2240}, doi = {10.1128/AEM.01444-06}, author = {Reguera, Gemma and Nevin, Kelly P and Nicoll, Julie S and Covalla, Sean F and Woodard, Trevor L and Lovley, Derek R} }