Biologically templated assembly of hybrid semiconducting nanomesh for high performance field effect transistors and sensors

Binding Capabilities of Different Genetically Engineered pVIII Proteins of the Filamentous M13/Fd Virus and Single-Walled Carbon Nanotubes

Binding functional biomolecules to non-biological materials, such as single-walled carbon nanotubes (SWNTs), is a challenging task with relevance for different applications. However, no one has yet undertaken a comparison of the binding of SWNTs to different recombinant filamentous viruses (phages) bioengineered to contain different binding peptides fused to the virus coat proteins. This is important due to the range of possible binding efficiencies and scenarios that may arise when the protein’s amino acid sequence is modified, since the peptides may alter the virus’s biological properties or they may behave differently when they are in the context of being displayed on the virus coat protein; in addition, non-engineered viruses may non-specifically adsorb to SWNTs. To test these possibilities, we used four recombinant phage templates and the wild type. In the first circumstance, we observed different binding capabilities and biological functional alterations; e.g., some peptides, in the context of viral templates, did not bind to SWNTs, although it was proven that the bare peptide did. The second circumstance was excluded, as the wild-type virus was found to hardly bind to the SWNTs. These results may be relevant to the possible use of the virus as a “SWNT shuttle” in nano-scale self-assembly, particularly since the pIII proteins are free to act as binding-directing agents. Therefore, knowledge of the differences between and efficiencies of SWNT binding templates may help in choosing better binding phages or peptides for possible future applications and industrial mass production.

All-Inkjet-Printed Flexible Nanobio-Devices with Efficient Electrochemical Coupling Using Amphiphilic Biomaterials

Nanostructured flexible electrodes with biological compatibility and intimate electrochemical coupling provide attractive solutions for various emerging bioelectronics and biosensor applications. Here, we develop all-inkjet-printed flexible nanobio-devices with excellent electrochemical coupling by employing amphiphilic biomaterial, an M13 phage, numerical simulation of single-drop formulation, and rational formulations of nanobio-ink. Inkjet-printed nanonetwork-structured electrodes of single-walled carbon nanotubes and M13 phage show efficient electrochemical coupling and hydrostability. Additive printing of the nanobio-inks also allows for systematic control of the physical and chemical properties of patterned electrodes and devices. All-inkjet-printed electrochemical field-effect transistors successfully exhibit pH-sensitive electrical current modulation. Moreover, all-inkjet-printed electrochemical biosensors fabricated via sequential inkjet-printing of the nanobio-ink, electrolytes, and enzyme solutions enable direct electrical coupling within the printed electrodes and detect glucose concentrations at as low as 20 μM. Glucose levels in sweat are successfully measured, and the change in sweat glucose levels is shown to be highly correlated with blood glucose levels. Synergistic combination of additive fabrication by inkjet-printing with directed assembly of nanostructured electrodes by functional biomaterials could provide an efficient means of developing bioelectronic devices for personalized medicine, digital healthcare, and emerging biomimetic devices.

Hydrodynamic Layer-by-Layer Assembly of Transferable Enzymatic Conductive Nanonetworks for Enzyme-Sticker-Based Contact Printing of Electrochemical Biosensors

Realizing high-performance electrochemical biosensors in a simple contact-printing-based approach significantly increases the applicability of integrated flexible biosensors. Herein, an enzyme-sticker-based approach that enables flexible and multielectrochemical sensors via simple contact-transfer printing is reported. The enzyme sticker consists of an enzymatic conductive network film and a polymeric support. The enzyme-incorporated nanostructured conductive network showing an efficient electrical coupling was assembled via the hydrodynamic layer-by-layer assembly of redox enzymes, polyelectrolytes, single-walled carbon nanotubes, and a biological glue material, M13 phage. The enzymatic conductive network on a polymeric membrane support was facilely wet contact-transfer printed onto integrated electrode systems by exploiting varying degrees of hydrophilicity displayed by the enzymatic electronic film, polymeric support, and receiving electrodes of the sensor system. The glucose sensors fabricated using the enzyme sticker detected glucose at a concentration of as low as 35 μM and showed high selectivity and stability. Furthermore, a flexible dual-sensor array capable of detecting both glucose and lactate was demonstrated using the versatile enzyme sticker concept. This work presents a new route toward assembling and integrating hybrid nanomaterials with efficient electrochemical coupling for high-performance biosensors and health-monitoring devices as well as for emerging bioelectronics and electrochemical devices.

Bio-fabrication of nanomesh channels of single-walled carbon nanotubes for locally gated field-effect transistors

Single-walled carbon nanotubes (SWNTs) are one of the promising electronic components for nanoscale electronic devices such as field-effect transistors (FETs) owing to their excellent device characteristics such as high conductivity, high carrier mobility and mechanical flexibility. Localized gating gemometry of FETs enables individual addressing of active channels and allows for better electrostatics via thinner dielectric layer of high k-value. For localized gating of SWNTs, it becomes critical to define SWNTs of controlled nanostructures and functionality onto desired locations in high precision. Here, we demonstrate that a biologically templated approach in combination of microfabrication processes can successfully produce a nanostructured channels of SWNTs for localized active devices such as local bottom-gated FETs. A large-scale nanostructured network, nanomesh, of SWNTs were assembled in solution using an M13 phage with strong binding affinity toward SWNTs and micrometer-scale nanomesh channels were defined using negative photolithography and plasma-etching processes. The bio-fabrication approach produced local bottom-gated FETs with remarkably controllable nanostructures and successfully enabled semiconducting behavior out of unsorted SWNTs. In addition, the localized gating scheme enhanced the device performances such as operation voltage and I _on/I _off ratio. We believe that our approach provides a useful and integrative method for fabricating electronic devices out of nanoscale electronic materials for applications in which tunable electrical properties, mechanical flexibility, ambient stability, and chemical stability are of crucial importance.