An official website of the United States government
Nanowires have substantial potential as the sensor component in electronic sensing devices. However, surface functionalization of traditional nanowire and nanotube materials with short peptides that increase sensor selectivity and sensitivity requires complex chemistries with toxic reagents. In contrast, microorganisms can assemble pilin monomers into protein nanowires with intrinsic conductivity from renewable feedstocks, yielding an electronic material that is robust and stable in applications, but also biodegradable. Here we report that the sensitivity and selectivity of protein nanowire-based sensors can be modified with a simple plug and play genetic approach in which a short peptide sequence, designed to bind the analyte of interest, is incorporated into the pilin protein that is microbially assembled into nanowires. We employed a scalable Escherichia coli chassis to fabricate protein nanowires that displayed either a peptide previously demonstrated to effectively bind ammonia, or a peptide known to bind acetic acid. Sensors comprised of thin films of the nanowires amended with the ammonia-specific peptide had a ca. 100-fold greater response to ammonia than sensors made with unmodified protein nanowires. Protein nanowires with the peptide that binds acetic acid yielded a 4-fold higher response than nanowires without the peptide. The protein nanowire-based sensors had greater responses than previously reported sensors fabricated with other nanomaterials. The results demonstrate that protein nanowires with enhanced sensor response for analytes of interest can be fabricated with a flexible genetic strategy that sustainably eliminates the energy, environmental, and health concerns associated with other common nanomaterials.
more »
« less
This content will become publicly available on March 13, 2026
Sensing devices fabricated with Escherichia coli expressing genetically tunable nanowires incorporated into a water-stable polymer
Electrically conductive, genetically tunable, pilin-based protein nanowires (ePNs) expressed in Escherichia coli grown on the biodiesel byproduct glycerol are a sustainable electronic material. They were previously shown to effectively function as sensing components for volatile analytes when deployed as thin films in electronic devices. However, thin-film devices are not suitable for analyzing components dissolved in water. To evaluate the possibility of fabricating a water-stable ePN matrix, ePNs purified from cells were mixed with polyvinyl butyral (PVB) to produce a transparent, electrically conductive, water-stable composite. ePN/PVB composite conductivity was tuned by changing the concentration of ePNs in the composite or genetically tailoring ePNs for different conductivities. Devices with an ePN/PVB sensing component rapidly responded in a linear fashion to changes in concentrations of dissolved ammonia or acetate. Genetically modifying nanowires to display an analyte-binding peptide on the ePN outer surface that was specific for ammonia or acetate increased sensing sensitivity and specificity. Composites comprised of whole cells of E. coli expressing ePNs and PVB were also electrically conductive. They functioned as sensing components whose sensitivity could also be tuned with the expression of ePNs displaying specific analyte-binding peptides. This approach avoids the laborious and time-consuming purification of protein nanowires from cells. The simplicity of sustainably fabricating an electronic sensing component with ePN-expressing E. coli mixed with a polymer, coupled with the potential of exquisitely tuning sensing specificity with facile ‘plug and play’ nanowire design, demonstrates the possibility of simply and inexpensively producing sensing devices for detecting a broad range of analytes.
more »
« less
- Award ID(s):
- 2027102
- PAR ID:
- 10649076
- Publisher / Repository:
- ELSEVIER
- Date Published:
- Journal Name:
- Biosensors and Bioelectronics
- Volume:
- 278
- ISSN:
- 0956-5663
- Page Range / eLocation ID:
- 117378
- Subject(s) / Keyword(s):
- Microbial nanowires, Nanowire sensor, e-biologics, Microbial electronic material, Nanowire composites, Sustainable electronics
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract We describe the concept and roadmap of an engineered electronic nose with specificity towards analytes that differ by as little as one carbon atom, and sensitivity of being able to electrically register a single molecule of analyte. The analyte could be anything that natural noses can detect, e.g. trinitrotoluene (TNT), cocaine, aromatics, volatile organic compounds etc. The strategy envisioned is to genetically engineer a fused olfactory odorant receptor (odorant receptor (OR), a membrane-bound G-protein coupled receptor (GPCR) with high selectivity) to an ion channel protein, which opens in response to binding of the ligand to the OR. The lipid bilayer supporting the fused sensing protein would be intimately attached to a nanowire or nanotube network (either via a covalent tether or a non-covalent physisorption process), which would electrically detect the opening of the ion channel, and hence the binding of a single ligand to a single OR protein domain. Three man-made technological advances: (1) fused GPCR to ion channel protein, (2) nanowire sensing of single ion channel activity, and (3) lipid bilayer to nanotube/nanowire tethering chemistry and on natural technology (sensitivity and selectivity of OR domains to specific analytes) each have been demonstrated and/or studied independently. The combination of these three technological advances and the result of millions of years of evolution of OR proteins would enable the goal of single molecule sensing with specificity towards analytes that differ by as little as one carbon atom. This is both a review of the past and a vision of the future.more » « less
-
The development of portable electronic chemical sensors is key to solving a number of challenges, including monitoring environmental and industrial hazards, as well as understanding and improving human health. Framework materials possess several desirable characteristics that make them well-suited for electroanalytical applications, including high surface area, atomically precise distribution of active sites, and tunable properties that can be leveraged through modular reticular chemistry. This review highlights the emergence of conductive framework materials as active components in electrically transduced chemical sensors, including the development of new materials for the detection of a wide variety of analytes in both gas and liquid phase. The efforts to gain fundamental understanding of the molecular interactions and sensing mechanisms between framework materials and analytes are described, along with applications of these materials on portable and flexible substrates. The review suggests areas for further study, including the study of material−analyte interactions at the molecular level and the continued development of scalable methods for the integration of framework materials into low-power, portable sensing devices.more » « less
-
Sensing complex gaseous mixtures and identifying their composition and concentration have the potential to achieve unprecedented improvements in environmental monitoring, medical diagnostics, industrial safety, and the food/agriculture industry. Electronically transduced chemical sensors capable of recognizing and differentiating specific target gases and transducing these chemical stimuli in a portable electronic device offer an opportunity for impact by bridging the utility of chemical information with global wireless connectivity. Among electronically transduced chemical sensors, chemiresistors stand out as particularly promising due to combined features of low-power requirements, room temperature operation, non-line-of-sight detection, high portability, and exceptional modularity. Relying on changes in resistance of a functional material triggered by variations in the surrounding chemical environment, these devices have achieved part-per-billion sensitivities of analytes by employing conductive polymers, graphene, carbon nanotubes (CNTs), metal oxides, metal nanoparticles, metal dichalcogenides, or MXenes as sensing materials. Despite these tremendous developments, the need for stable, selective, and sensitive chemiresistors demands continued innovation in material design in order to operate in complex mixtures with interferents as well as variations in humidity and temperature. To fill existing gaps in sensing capabilities, conductive metal−organic frameworks (MOFs) and covalent organic frameworks (COFs) have recently emerged as a promising class of materials for chemiresistive sensing. In contrast to previously reported chemiresistors, these materials offer at least three unique features for gas sensing applications: (i) bottom-up synthesis from molecularly precise precursors that allows for strategic control of material−analyte interactions, (ii) intrinsic conductivity that simultaneously facilitates charge transport and signal transduction under low power requirements, and (iii) high surface area that enables the accessibility of abundant active sites and decontamination of gas streams by coordinating to and, sometimes, detoxifying harmful analytes. Through an emphasis on molecular engineering of structure−property relationships in conductive MOFs and COFs, combined with strategic innovations in device integration strategies and device form factor (i.e., the physical dimensions and design of device components), our group has paved the way to demonstrating the multifunctional utility of these materials in the chemiresistive detection of gases and vapors. Backed by spectroscopic assessment of material−analyte interactions, we illustrated how molecular-level features lead to device performance in detection, filtration, and detoxification of gaseous analytes. By merging the bottom-up synthesis of these materials with device integration, we show the versatility and scalability of using these materials in low-power electronic sensing devices. Taken together, our achievements, combined with the progress spearheaded on this class of materials by other researchers, establish conductive MOFs and COFs as promising multifunctional materials for applications in electronically transduced, portable, low-power sensing devices.more » « less
-
Abstract Conductive adhesives are required for the integration of dissimilar material components to create soft electronic and robotic systems. Here, a heterogeneous liquid metal‐based conductive adhesive is developed that reversibly attaches to diverse surfaces with high stretchability (>100% strain), low modulus (<100 kPa), and strain‐invariant electrical conductivity. This SofT integrated composite with tacK through liquid metal (STICK‐LM) adhesive consists of a heterogeneous graded film with a liquid metal‐rich side that is embossed at prescribed locations for electrical conductivity and an electrically insulating adhesive side for integration. Adhesion behavior is tuned for adhesion energies > 70 Jm−2(≈ 25x enhancement over unmodified composites) and described with a viscoelastic analysis, providing design guidelines for controllable yet reversible adhesion in electrically conductive systems. The architecture of STICK‐LM adhesives provides anisotropic and heterogeneous electrical conductivity and enables direct integration into soft functional systems. This is demonstrated with deformable fuses for robotic joints, repositionable electronics that rapidly attach on curvilinear surfaces, and stretchable adhesive conductors with nearly constant electrical resistance. This study provides a methodology for electrically conductive, reversible adhesives for electrical and mechanical integration of multicomponent systems in emerging technologies.more » « less
