scholarly journals Controlling Redox Enzyme Orientation at Planar Electrodes

Catalysts ◽  
2018 ◽  
Vol 8 (5) ◽  
pp. 192 ◽  
Author(s):  
Vivek Hitaishi ◽  
Romain Clement ◽  
Nicolas Bourassin ◽  
Marc Baaden ◽  
Anne De Poulpiquet ◽  
...  
Keyword(s):  
Electrode Surface ◽  
Direct Electron Transfer ◽  
Electronic Conductivity ◽  
Analytical Techniques ◽  
Redox Enzymes ◽  
Sensing Applications ◽  
Planar Electrodes ◽  
The Rich ◽  
Living Organisms ◽  
Electron Transfers

Redox enzymes, which catalyze reactions involving electron transfers in living organisms, are very promising components of biotechnological devices, and can be envisioned for sensing applications as well as for energy conversion. In this context, one of the most significant challenges is to achieve efficient direct electron transfer by tunneling between enzymes and conductive surfaces. Based on various examples of bioelectrochemical studies described in the recent literature, this review discusses the issue of enzyme immobilization at planar electrode interfaces. The fundamental importance of controlling enzyme orientation, how to obtain such orientation, and how it can be verified experimentally or by modeling are the three main directions explored. Since redox enzymes are sizable proteins with anisotropic properties, achieving their functional immobilization requires a specific and controlled orientation on the electrode surface. All the factors influenced by this orientation are described, ranging from electronic conductivity to efficiency of substrate supply. The specificities of the enzymatic molecule, surface properties, and dipole moment, which in turn influence the orientation, are introduced. Various ways of ensuring functional immobilization through tuning of both the enzyme and the electrode surface are then described. Finally, the review deals with analytical techniques that have enabled characterization and quantification of successful achievement of the desired orientation. The rich contributions of electrochemistry, spectroscopy (especially infrared spectroscopy), modeling, and microscopy are featured, along with their limitations.

scholarly journals Direct Electron Transfer-Type Bioelectrocatalysis of Redox Enzymes at Nanostructured Electrodes

Catalysts ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 236 ◽  
Author(s):  
Taiki Adachi ◽  
Yuki Kitazumi ◽  
Osamu Shirai ◽  
Kenji Kano
Keyword(s):  
Electron Transfer ◽  
Protein Engineering ◽  
Electrode Surface ◽  
Direct Electron Transfer ◽  
Redox Enzymes ◽  
Type Reaction ◽  
The Past ◽  
Electrode Reactions ◽  
Basic Concepts ◽  
Catalytic Functions

Direct electron transfer (DET)-type bioelectrocatalysis, which couples the electrode reactions and catalytic functions of redox enzymes without any redox mediator, is one of the most intriguing subjects that has been studied over the past few decades in the field of bioelectrochemistry. In order to realize the DET-type bioelectrocatalysis and improve the performance, nanostructures of the electrode surface have to be carefully tuned for each enzyme. In addition, enzymes can also be tuned by the protein engineering approach for the DET-type reaction. This review summarizes the recent progresses in this field of the research while considering the importance of nanostructure of electrodes as well as redox enzymes. This review also describes the basic concepts and theoretical aspects of DET-type bioelectrocatalysis, the significance of nanostructures as scaffolds for DET-type reactions, protein engineering approaches for DET-type reactions, and concepts and facts of bidirectional DET-type reactions from a cross-disciplinary viewpoint.

scholarly journals Direct Electron Transfer-type Bioelectrocatalysis of Redox Enzymes at Nanostructured Electrodes

2020 ◽  
Author(s):  
Taiki Adachi ◽  
Yuki Kitazumi ◽  
Osamu Shirai ◽  
Kenji Kano
Keyword(s):  
Electron Transfer ◽  
Protein Engineering ◽  
Electrode Surface ◽  
Direct Electron Transfer ◽  
Redox Enzymes ◽  
Type Reaction ◽  
The Past ◽  
Electrode Reactions ◽  
Basic Concepts ◽  
Catalytic Functions

Direct electron transfer (DET)-type bioelectrocatalysis, which couples electrode reactions and catalytic functions of redox enzymes without any redox mediator, is one of the most intriguing subjects studied over the past decades in the field of bioelectrochemistry. In order to realize the DET-type bioelectrocatalysis and to improve the performance, nanostructures of the electrode surface have to be carefully tuned for each enzyme. In addition, enzymes can also be tuned by protein engineering approach for the DET-type reaction. This review summarizes the resent progresses in this field of the research, while taking into consideration of the importance of nanostructure of electrodes as well as redox enzymes. Described are basic concepts and theoretical aspects of DET-type bioelectrocatalysis, significance of nanostructures as scaffolds for DET-type reactions, protein engineering approached for DET-type reactions, and concepts and facts of bidirectional DET-type reactions, from a cross-disciplinary viewpoint.

Quantum transport, electronic properties and molecular adsorptions in graphene

2021 ◽  
Vol 35 (08) ◽  
pp. 2130001
Author(s):  
Yoshitaka Fujimoto
Keyword(s):  
Electronic Properties ◽  
Quantum Transport ◽  
Density Functional ◽  
Field Effect Transistors ◽  
Electronic Conductivity ◽  
Volume Ratio ◽  
Functional Study ◽  
Sensor Applications ◽  
Sensing Applications ◽  
High Electronic Conductivity

Molecular sensor applications are used in different fields including environmental monitoring and medical diagnosis. Graphene, a single atomic layer consisting of the hexagonally arranged carbon material, is one of the most promising materials for ideal channels in field-effect transistors to be used as electronic sensing applications owing to its lightweight, mechanical robustness, high electronic conductivity and large surface-to-volume ratio. This paper provides a review of molecular adsorptions, electronic properties and quantum transport of graphene based on the first-principles density-functional study. The adsorption properties of environmentally polluting or toxic molecules and electronic transport of graphene are revealed. The possibility of detecting these molecules selectively is also discussed for designing the graphene-based sensor applications.

Synthesis, Characterization, Applications, and Toxicity of Green Synthesized Nanoparticles

2021 ◽  
Vol 22 ◽  
Author(s):  
João Marcos Pereira Galúcio ◽  
Sorrel Godinho Barbosa de Souza ◽  
Arthur Abinader Vasconcelos ◽  
Alan Kelbis Oliveira Lima ◽  
Kauê Santana da Costa ◽  
...  
Keyword(s):  
Green Synthesis ◽  
Low Cost ◽  
Chemical Properties ◽  
Analytical Techniques ◽  
Industrial Applications ◽  
Synthesis Methods ◽  
Methods Of Synthesis ◽  
Food Applications ◽  
Living Organisms ◽  
Harmful Effects

: Nanotechnology is a cutting-edge area with numerous industrial applications. Nanoparticles are structures that have dimensions ranging from 1–100 nm which exhibit significantly different mechanical, optical, electrical, and chemical properties when compared with their larger counterparts. Synthetic routes that use natural sources, such as plant extracts, honey, and microorganisms are environmentally friendly and low-cost methods that can be used to obtain nanoparticles. These methods of synthesis generate products that are more stable and less toxic than those obtained using conventional methods. Nanoparticles formed by titanium dioxide, zinc oxide, silver, gold, and copper, as well as cellulose nanocrystals are among the nanostructures obtained by green synthesis that have shown interesting applications in several technological industries. Several analytical techniques have also been used to analyze the size, morphology, hydrodynamics, diameter, and chemical functional groups involved in the stabilization of the nanoparticles as well as to quantify and evaluate their formation. Despite their pharmaceutical, biotechnological, cosmetic, and food applications, studies have detected their harmful effects on human health and the environment; and thus, caution must be taken in uses involving living organisms. The present review aims to present an overview of the applications, the structural properties, and the green synthesis methods that are used to obtain nanoparticles, and special attention is given to those obtained from metal ions. The review also presents the analytical methods used to analyze, quantify, and characterize these nanostructures.

scholarly journals Influence of the Sputtering Technique and Thermal Annealing on YSZ Thin Films for Oxygen Sensing Applications

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1165
Author(s):  
Emilio Paz Alpuche ◽  
Pascal Gröger ◽  
Xuetao Wang ◽  
Thomas Kroyer ◽  
Stefanos Fasoulas
Keyword(s):  
Thin Films ◽  
Gas Sensors ◽  
Electronic Conductivity ◽  
Film Surface ◽  
Annealing Treatment ◽  
Thin Film Surface ◽  
Sensing Applications ◽  
Partial Pressures ◽  
Sensor Current ◽  
Oxygen Gas

Yttria-stabilized zirconia (YSZ) thin films were deposited using direct current (reactive and metallic) and radio frequency magnetron sputtering. The effect of the deposition technique and annealing treatment on the microstructure and crystallinity of the thin films was assessed. Using the films produced in this work, oxygen gas sensors were built and their performance under vacuum conditions was evaluated. All the films exhibited a cubic crystalline structure after a post-deposition thermal treatment, regardless of the sputtering technique. When the annealing treatment surpassed 1000 °C, impurities were detected on the thin film surface. The oxygen gas sensors employing the reactive and oxide-sputtered YSZ thin films displayed a proportional increase in the sensor current as the oxygen partial pressure was increased in the evaluated pressure range (5 × 10−6 to 2 × 10−3 mbar). The sensors which employed the metallic-deposited YSZ films suffered from electronic conductivity at low partial pressures.

scholarly journals Recent advances in analysis of trace elements in environmental samples by X-ray based techniques (IUPAC Technical Report)

2019 ◽  
Vol 91 (6) ◽  
pp. 1029-1063 ◽  
Author(s):  
Roberto Terzano ◽  
Melissa A. Denecke ◽  
Gerald Falkenberg ◽  
Bradley Miller ◽  
David Paterson ◽  
...  
Keyword(s):  
Trace Elements ◽  
Environmental Samples ◽  
Analytical Techniques ◽  
Anthropogenic Pollution ◽  
Chemical Extraction ◽  
Environmental Matrices ◽  
Environmental Sciences ◽  
X Ray ◽  
Environmental Media ◽  
Living Organisms

Abstract Trace elements analysis is a fundamental challenge in environmental sciences. Scientists measure trace elements in environmental media in order to assess the quality and safety of ecosystems and to quantify the burden of anthropogenic pollution. Among the available analytical techniques, X-ray based methods are particularly powerful, as they can quantify trace elements in situ. Chemical extraction is not required, as is the case for many other analytical techniques. In the last few years, the potential for X-ray techniques to be applied in the environmental sciences has dramatically increased due to developments in laboratory instruments and synchrotron radiation facilities with improved sensitivity and spatial resolution. In this report, we summarize the principles of the X-ray based analytical techniques most frequently employed to study trace elements in environmental samples. We report on the most recent developments in laboratory and synchrotron techniques, as well as advances in instrumentation, with a special attention on X-ray sources, detectors, and optics. Lastly, we inform readers on recent applications of X-ray based analysis to different environmental matrices, such as soil, sediments, waters, wastes, living organisms, geological samples, and atmospheric particulate, and we report examples of sample preparation.

scholarly journals Rational Surface Modification of Carbon Nanomaterials for Improved Direct Electron Transfer-Type Bioelectrocatalysis of Redox Enzymes

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1447
Author(s):  
Hongqi Xia ◽  
Jiwu Zeng
Keyword(s):  
Electron Transfer ◽  
Surface Modification ◽  
Recent Progress ◽  
Carbon Nanomaterials ◽  
Direct Electron Transfer ◽  
Rational Surface ◽  
Interfacial Electron Transfer ◽  
Redox Enzymes ◽  
Oriented Immobilization

Interfacial electron transfer between redox enzymes and electrodes is a key step for enzymatic bioelectrocatalysis in various bioelectrochemical devices. Although the use of carbon nanomaterials enables an increasing number of redox enzymes to carry out bioelectrocatalysis involving direct electron transfer (DET), the role of carbon nanomaterials in interfacial electron transfer remains unclear. Based on the recent progress reported in the literature, in this mini review, the significance of carbon nanomaterials on DET-type bioelectrocatalysis is discussed. Strategies for the oriented immobilization of redox enzymes in rationally modified carbon nanomaterials are also summarized and discussed. Furthermore, techniques to probe redox enzymes in carbon nanomaterials are introduced.

Characterization of Mercaptoethylamine-Modified Gold Electrode Surface and Analyses of Direct Electron Transfer to Putidaredoxin

Langmuir ◽  
1995 ◽  
Vol 11 (12) ◽  
pp. 4818-4822 ◽  
Author(s):  
Ling Sang Wong ◽  
Vincent L. Vilker ◽  
William T. Yap ◽  
Vytas Reipa
Keyword(s):  
Electron Transfer ◽  
Electrode Surface ◽  
Gold Electrode ◽  
Direct Electron Transfer

Comparative Spectroscopic Analysis of Maya Wall Paintings from Ek’Balam, Mexico

2014 ◽  
Vol 1618 ◽  
pp. 63-72 ◽  
Author(s):  
A. Alonso ◽  
N. A. Pérez ◽  
J. L. Ruvalcaba Sil ◽  
E. Casanova ◽  
P. Claes ◽  
...  
Keyword(s):  
Spectroscopic Analysis ◽  
Analytical Techniques ◽  
Archaeological Site ◽  
X Ray Diffraction ◽  
X Ray ◽  
Non Invasive ◽  
Yellow Orange ◽  
Pigment Distribution ◽  
The Rich ◽  
Invasive Techniques

ABSTRACTThe Maya archaeological site of Ek’Balam is located in Yucatán, Mexico. This place is known for its artistic tradition of reliefs modeled in stucco as well as the rich pictorial and hieroglyphic texts. Although the mural played a key role in the artistic program architectural of elite groups, most of these remains have not been studied, either by its incomplete or fragile condition, or by localization in inaccessible substructures.In this study, technical aspects of the mural paintings from rooms 12 and 50 of the main building of the site are addressed by the spectroscopic analysis of its materials. Optical microscopy was used to observe the layers superposition and pigment distribution, while the stucco and rock support were characterized by X-ray Diffraction (XRD) and X-ray Fluorescence (XRF). Moreover, the chromatic palette composed of different colors and tones of red, yellow, orange, green, blue and black were analyzed mainly with non-invasive techniques using Raman and FTIR spectroscopies as well as XRF.The information obtained from the combination of these analytical techniques, allowed a better understanding of the similarities and differences between these two rooms that were built during the last construction stage of the Acropolis. These results were also compared with previous analyses of mural painting of this site and other Maya paintings.

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