Development Of Bioelectronic Devices Research Articles

Light-driven proton transmembrane transport enabled by bio-semiconductor 2D membrane: A general peptide-induced WS2 band shifting strategy

Light-driven proton directional transport is important in living beings as it could subtly realize the light energy conversion for living uses. In the past years, 2D materials-based nanochannels have shown great potential in active ion transport due to controllable properties, including surface charge distribution, wettability, functionalization, electric structure, and external stimuli responsibility, etc. However, to fuse the inorganic materials into bio-membranes still faces several challenges. Here, we proposed peptide-modified WS2 nanosheets via cysteine linkers to realize tunable band structure and, hence, enable light-driven proton transmembrane transport. The modification was achieved through the thiol chemistry of the –SH groups in the cysteine linker and the S vacancy on the WS2 nanosheets. By tuning the amino residues sequences (lysine-rich peptides, denoted as KFC; and aspartate-rich peptides, denoted as DFC), the ζ-potential, surface charge, and band energy of WS2 nanosheets could be rationally regulated. Janus membranes formed by assembling the peptide-modified WS2 nanosheets could realize the proton transmembrane transport under visible light irradiation, driven by a built-in potential due to a type II band alignment between the KFC-WS2 and DFC-WS2. As a result, the proton would be driven across the formed nanochannels. These results demonstrate a general strategy to build bio-semiconductor materials and provide a new way for embedding inorganic materials into biological systems toward the development of bioelectronic devices.

Biosynthetic Electronic Interfaces for Bridging Microbial and Inorganic Electron Transfer

Electron transport in biological and inorganic systems is mediated through distinct mechanisms and pathways. Their fundamental mismatch in structural and thermodynamic properties has imposed significant challenge on the effective coupling at the biotic/abiotic interface, which is central to the design and development of bioelectronic devices and their translation towards various engineering applications. Using electrochemically active bacteria, such as G. sulfurreducens, as a model system, here we report a bottom-up, bio-synthetic approach to synergize the electron transport and significantly enhance the coupling at the heterogeneous junction. In particular, graphene oxide was exploited as the respiratory electron acceptors, which can be directly reduced by G. sulfurreducens through extracellular electron transfer, closely coupled with outer membrane cytochromes in electroactive conformation, and actively “wire” the redox centers to external electrical contacts. Through this strategy, the contact resistance at the biofilm-electrode interface can be effectively reduced by 90%. Furthermore, the cyclic voltammetry reveals that the electron transfer of DL-1 biofilm transformed from a low-current (~0.36 µA), rate-limited profile to a high-current (~5µA), diffusion-limited profile. These results suggested that the integration of rGO can minimize the charge transfer barriers at the biofilm-electrode interface. The more transparent contact at DL-1/electrode interface can enable unambiguous characterization of the inherent electron transport kinetics across the electroactive biofilm which can be modeled as a R(resistor) C (capacitor) circuit with critical frequency at 1000Hz. The current work represents a strategically new approach toward the seamless integration of biological and artificial electronics, which is expected to provide critical insights into the fundamentals of biological electron transport and open up new opportunities for applications in biosensing, biocomputing and bioenergy conversion. Figure 1

Biosynthetic Electronic Interfaces for Bridging Microbial and Inorganic Electron Transport.

Electron transport in biological and inorganic systems is mediated through distinct mechanisms and pathways. Their fundamental mismatch in structural and thermodynamic properties has imposed a significant challenge on the effective coupling at the biotic/abiotic interface, which is central to the design and development of bioelectronic devices and their translation toward various engineering applications. Using electrochemically active bacteria, such as G. sulfurreducens, as a model system, here we report a bottom-up, biosynthetic approach to synergize the electron transport and significantly enhance the coupling at the heterogeneous junction. In particular, graphene oxide was exploited as the respiratory electron acceptors, which can be directly reduced by G. sulfurreducens through extracellular electron transfer, closely coupled with outer membrane cytochromes in electroactive conformation, and actively "wire" the redox centers to external electrical contacts. Through this strategy, the contact resistance at the biofilm/electrode interface can be effectively reduced by 90%. Furthermore, the cyclic voltammetry reveals that the electron transfer of the DL-1 biofilm transformed from a low-current (∼0.36 μA), rate-limited profile to a high-current (∼5 μA), diffusion-limited profile. These results suggested that the integration of rGO can minimize the charge transfer barriers at the biofilm/electrode interface. The more transparent contact at the DL-1/electrode interface also enables unambiguous characterization of the inherent electron transport kinetics across the electroactive biofilm independent of cell/electrode interactions. The current work represents a strategically new approach toward the seamless integration of biological and artificial electronics, which is expected to provide critical insights into the fundamentals of biological electron transport and open up new opportunities for applications in biosensing, biocomputing, and bioenergy conversion.

Electron transfer and electrocatalytics of cytochrome c and horseradish peroxidase on DNA modified electrode

A bio-interphase composed of DNA, cytochrome c (Cyt c) and horseradish peroxidase (HRP) was developed by layer-by-layer assembling Cyt c, DNA and Cyt c-HRP on biocompatible 11-mercaptoundecanoic acid - 6-mercapto-1-hexanol modified gold electrode. The new bio-interphase was used as a model system to mimic the electron transfer and electrocatalytic performance of two proteins in living organisms. Results showed that the electron transfer rate at bi-protein bio-interphase was faster than those at the single protein bio-interphase, indicating a synergistic interaction between the two proteins occurred in the electron transfer. Moreover, the mixed proteins modified electrode exhibited good electrocatalytic response to reduction of hydrogen peroxide (H2O2) and oxygen (O2), suggesting that it could be used as a sensor for H2O2 and O2 detection. The properties of the bio-interphase, together with the bioelectrocatalytic activity, could make it useful in the development of bioelectronic devices, and investigation of electrochemistry of other heme proteins at functional interphase. It would also provide a new strategy for further study on the electron transfer of other multi-proteins in a bio-interphase and the development of biosensors.

Human sulfite oxidase electrochemistry on gold nanoparticles modified electrode

The present study reports a facile approach for sulfite biosensing, based on enhanced direct electron transfer of a human sulfite oxidase (hSO) immobilized on a gold nanoparticles modified electrode. The spherical core shell AuNPs were prepared via a new method by reduction of HAuCl4 with branched poly(ethyleneimine) in an ionic liquids resulting particles with a diameter less than 10nm. These nanoparticles were covalently attached to a mercaptoundecanoic acid modified Au-electrode where then hSO was adsorbed and an enhanced interfacial electron transfer and electrocatalysis was achieved. UV/Vis and resonance Raman spectroscopy, in combination with direct protein voltammetry, are employed for the characterization of the system and reveal no perturbation of the structural integrity of the redox protein. The proposed biosensor exhibited a quick steady-state current response, within 2s, a linear detection range between 0.5 and 5.4μM with a high sensitivity (1.85nAμM−1). The investigated system provides remarkable advantages in the possibility to work at low applied potential and at very high ionic strength. Therefore these properties could make the proposed system useful in the development of bioelectronic devices and its application in real samples.

Direct electrochemistry and electrocatalysis of hemoglobin on chitosan-room temperature ionic liquid-TiO 2-graphene nanocomposite film modified electrode

TiO 2-graphene nanocomposite was prepared by hydrolysis of titanium isopropoxide in colloidal suspension of graphene oxide and in situ hydrothermal treatment. The direct electrochemistry and electrocatalysis of hemoglobin in room temperature ionic liquid 1-Butyl-3-methylimidazolium hexafluorophosphate, chitosan and TiO 2-graphene nanocomposite modified glassy carbon electrode were investigated. The biosensor was examined by using UV-vis spectroscopy, scanning electron microscopy and electrochemical methods. The results indicated that hemoglobin remained its bioactivity on the modified electrode, showing a couple of well-defined and quasi-reversible redox peaks, corresponding to hemoglobin Fe III/Fe II couple. The kinetic parameters for the electrode reaction, such as the formal potential ( E o'), the electron transfer rate constant ( k s), the apparent coverage ( Γ), and Michaelis–Menten constant ( K m) were evaluated. The biosensor showed good electrochemical responses to the reduction of H 2O 2 in the ranges of 1–1170 μM. The detection limit was 0.3 μM (S/N = 3). The properties of this composite film, together with the bioelectrochemical catalytic activity, could make them useful in the development of bioelectronic devices, and investigation of electrochemistry of other heme proteins at functional interface.

Amplification of bioelectrocatalytic signalling based on silver nanoparticles and DNA-derived horseradish peroxidase biosensors

Horseradish peroxidase (HRP) was immobilized onto a polyion complex membrane containing positively charged silver nanoparticles (nanosilver), double stranded DNA and poly(thionine) to fabricate highly sensitive and selective electrochemical hydrogen peroxide (H2O2) biosensor on a glassy carbon electrode. The presence of nanosilver provided a biocompatible microenvironment for enzyme molecules, greatly amplified the surface coverage of HRP on the electrode surface, and most importantly could act as a charge carrier. The process of the biosensor construction was characterized by scanning electron microscopy. Voltammetric and time-based amperometric techniques were employed to characterize the properties of the derived biosensor. Under optimal conditions, the biosensor has an electrocatalytic behavior towards the H2O2 reduction, and exhibits a linear range from 1.1 µM to 5.2 mM, with a lower detection limit of 0.2 µM. The apparent Michaelis–Menten constant of the biosensor to H2O2 was estimated to be 1.02 mM. Furthermore, the biosensor exhibited high sensitivity, good reproducibility, and acceptable stability. Importantly, the properties of composite film, together with the bioelectrochemical catalytic activity, could make them useful in the development of bioelectronic devices and investigation of protein electrochemistry at functional interface.

Direct electrochemistry of hemoglobin in TATP film: Application in biological sensor

The composite film assembled by hemoglobin and triacetone triperoxide (Hb–TATP) is described. This film is characterized by ultraviolet visible (UV–vis) absorption, reflectance absorbance infrared (RAIR) spectra, and electrochemistry. On the surface of carbon paste electrode (CPE), the film gives a pair of well-defined, nearly reversible redox waves, corresponding to Hb Fe III/Fe II couple. The kinetic parameters for the electrode reaction, such as the formal potential ( E°′), the electron transfer rate constant ( k s), and the apparent coverage ( Г) are evaluated. The E°′ value is dependent on the pH of external solution. Immobilized Hb exhibits excellent enzyme-like electrocatalytic activities to O 2 and H 2O 2 reductions. The linear range and the detection limit for H 2O 2 determination are reported. The properties of this composite film, together with the bioelectrochemical catalytic activity, could make them useful in the development of bioelectronic devices and investigation electrochemistry of other heme proteins at functional interface.

Novel amperometric biosensor based on composite film assembled by polyelectrolyte-surfactant polymer, carbon nanotubes and hemoglobin

A novel hydrogen peroxide biosensor has been developed based on the encapsulation of hemoglobin (Hb) in the composite film of carboxylic carbon nanotubes and polyelectrolyte-surfactant polymer. The direct electron transfer of the Hb entrapped in the composite film was observed. The formal potential of the encapsulated Hb was −0.287 V versus SCE and the heterogeneous electron transfer rate constant was 0.4 s −1 in a 0.1 M phosphate buffer solution (pH 7.0). An FT-IR spectroscopy study confirms that the secondary structure of Hb encapsulated in the composite film still retains the original arrangement. It is suggested that the achieved faradic response of the hemoglobin be due to the promotion properties of carbon nanotube in electron transfer in biomembrane-like polyelectrolyte-surfactant polymer. The entrapped Hb exhibited excellent electrocatalytic activity to reduce hydrogen peroxide. The properties of functional composite film, together with the bioelectrochemical catalytic activity, could make them useful in the development of bioelectronic devices and investigation of protein electrochemistry at functional interface.