e-Biologics: Fabrication of Sustainable Electronics with “Green” Biological Materials

Abstract

The growing ubiquity of electronic devices is increasingly consuming substantial energy and rare resources for materials fabrication, as well as creating expansive volumes of toxic waste. This is not sustainable. Electronic biological materials (e-biologics) that are produced with microbes, or designed with microbial components as the guide for synthesis, are a potential green solution. Some e-biologics can be fabricated from renewable feedstocks with relatively low energy inputs, often while avoiding the harsh chemicals used for synthesizing more traditional electronic materials. Several are completely free of toxic components, can be readily recycled, and offer unique features not found in traditional electronic materials in terms of size, performance, and opportunities for diverse functionalization. An appropriate investment in the concerted multidisciplinary collaborative research required to identify and characterize e-biologics and to engineer materials and devices based on e-biologics could be rewarded with a new “green age” of sustainable electronic materials and devices.

Conductive Composite Materials Fabricated from Microbially Produced Protein Nanowires

“…Moreover, whereas synthetic organic materials preparation typically requires high temperatures and/or expensive/toxic reagents, e-PNs are produced at room temperature in bioreactors from inexpensive feedstocks, contain no toxic components, and degrade into benign products that can serve as a feedstock for methane production. [2] These considerations, combined with the proof-of-concept study reported here, suggest that e-PNs may be a desirable and effective conductive component for an array of electronic materials including sensors, [10] conducting hydrogels, [16] and flexible bioelectronics.…”

“…The electrically conductive protein nanowires (e‐PNs) of the microorganism Geobacter sulfurreducens are unique among proteins for their ability to conduct electrons over micrometer‐scale distances . These proteins, which have been referred to as “microbial nanowires” or e‐pili in a biological context, show promise as “green” electronic materials because they can be produced sustainably from inexpensive renewable feedstocks and contain no toxic components . Attractive features of e‐PNs include their high aspect ratio (3 nm × 10–30 µm) and tunable conductivity over a wide range (10 −6 –10 3 S cm −1 ) by genetically tailoring their amino acid sequences …”

“…The electrically conductive protein nanowires (e-PNs) of the microorganism Geobacter sulfurreducens are unique among proteins for their ability to conduct electrons over micrometer-scale distances. [1,2] These proteins, which have been referred to as "microbial nanowires" or e-pili in a biological context, [1,3] show 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 × 10-30 µm) from renewable organic feedstocks.…”

“…Biosynthetic Nanocomposites promise as "green" electronic materials because they can be produced sustainably from inexpensive renewable feedstocks and contain no toxic components. [1,2] Attractive features of e-PNs include their high aspect ratio (3 nm × 10-30 µm) and tunable conductivity over a wide range (10 −6 -10 3 S cm −1 ) by genetically tailoring their amino acid sequences. [3][4][5][6][7][8] Potential applications of e-PNs could be expanded by their use in conjunction with soft materials, such as polymers, to give biosynthetic hybrid structures that are related conceptually to polymer-based composites containing carbon nanotubes (CNTs) or metallic nanowires.…”

A pilin chaperone required for the expression of electrically conductive Geobacter sulfurreducens pili

“…The electrically conductive pili (e‐pili) of Geobacter sulfurreducens present a paradigm shift for long‐range biological electron transport and offer new possibilities for the fabrication of sustainable electron materials (Lovley, ; Malvankar and Lovley, ; Lovley, ,b). They serve as a model for similar pili found in diverse microorganisms (Holmes et al ., ; Walker et al ., ).…”