Direct Electrochemistry and Electrocatalysis of Hemoglobin at Mesoporous Carbon Modified Electrode

The novel highly ordered mesoporous carbon (known as FDU-15), prepared by the organic-organic self-assembly method was been used for first time for the immobilization of hemoglobin (Hb) and its bioelectrochemical properties were studied. The resulting Hb/FDU-15 film provided a favorable microenvironment for Hb to perform direct electron transfers at the electrode. The immobilized Hb also displayed its good electrocatalytic activity for the reduction of hydrogen peroxide. The results demonstrate that mesoporous carbon FDU-15 can improve the Hb loading with retention of its bioactivity and greatly promote the direct electron transfer, which can be attributed to its high specific surface area, uniform ordered porous structure, suitable pore size and biocompatibility. Our present study may provide an alternative way for the construction of nanostructure biofunctional surfaces and pave the way for its application to biosensors

Modified Electrodes for Determining Trace Metal Ions

Due to all the advantages of low cost, speed, and simplicity, electrochemistry has always represented a perfect choice to be selected in quantitative analysis particularly in the case of metal ions but with the drawback of specificity and sensitivity. With the arrival of nanomaterials, the problem of sensitivity and limit of detection has been overcome and a great variety of applications of electrochemistry especially in trace analysis are highlighted. Layers of materials can be arranged and manipulated to make the methods more specific to targeting analytes The opportunity is there for both older and newer methods to be beneficial in a large number of applications with superb analytical performance. This knowledge of modified electrodes can inspire newer and greater innovative applications of electrochemistry with the promising extension to other areas under current interests

Catalase-based modified graphite electrode for hydrogen peroxide detection in different beverages

A catalase-based (NAF/MWCNTs) nanocomposite film modified glassy carbon electrode for hydrogen peroxide (H2O2) detection was developed. The developed biosensor was characterized in terms of its bioelectrochemical properties. Cyclic voltammetry (CV) technique was employed to study the redox features of the enzyme in the absence and in the presence of nanomaterials dispersed in Nafion polymeric solution. The electron transfer coefficient, , and the electron transfer rate constant, , were found to be 0.42 and 1.71 s−1, at pH 7.0, respectively. Subsequently, the same modification steps were applied to mesoporous graphite screenprinted electrodes. Also, these electrodes were characterized in terms of their main electrochemical and kinetic parameters. The biosensor performances improved considerably after modification with nanomaterials. Moreover, the association of Nafion with carbon nanotubes retained the biological activity of the redox protein. The enzyme electrode response was linear in the range 2.5– 1150 mol L−1, with LOD of 0.83 mol L−1. From the experimental data, we can assess the possibility of using the modified biosensor as a useful tool for H2O2 determination in packaged beverages

Nitrite Biosensing via Selective Enzymes—A Long but Promising Route

The last decades have witnessed a steady increase of the social and political awareness for the need of monitoring and controlling environmental and industrial processes. In the case of nitrite ion, due to its potential toxicity for human health, the European Union has recently implemented a number of rules to restrict its level in drinking waters and food products. Although several analytical protocols have been proposed for nitrite quantification, none of them enable a reliable and quick analysis of complex samples. An alternative approach relies on the construction of biosensing devices using stable enzymes, with both high activity and specificity for nitrite. In this paper we review the current state-of-the-art in the field of electrochemical and optical biosensors using nitrite reducing enzymes as biorecognition elements and discuss the opportunities and challenges in this emerging market

Hemoprotein-Mediated Activation of Nitroalkanes

Chemicals and drugs are known to be metabolized mostly by Cytochrome P450 xenobiotic metabolizing enzymes. However, the detailed mechanism of nitro-compounds metabolism is still unclear. The activation of nitro-xenobiotics by heme-P450 enzymes is a potential explanation for the origin of nitro-compound carcinogenesis. Investigating the interaction of simple nitro-compounds with redox activity of heme enzymes is therefore critical to explore the mechanism and products of activation. In this study, multiple analytical methods and instrumentations are employed and graphic and simulation software such as Origin® and Digisim® are utilized to quantitatively derive parameters from experimental raw data. This study shows that myoglobin, iron-protoporphyrin-IX (hemin), and the oxygenase domain of inducible nitric oxide synthase (iNOSoxy) act as efficient electrocatalysts for nitroalkane reductions in the surfactant films on pyrolytic graphite electrodes. In the study using myoglobin as a model electrocatalyst for the electroreduction of nitromethane, the catalytic activity is evaluated using Michaelis-Menten kinetics. The apparent Km and the turnover number kcat are derived from non-linear regression of Michaelis-Menten plot using Origin software. The reductive products of catalytic electroreduction of nitromethane are identified by a mass spectrometric method. We also identified a ferrous heme-nitrosomethane as the intermediate in the catalytic process using UV-Vis spectroscopy and electrochemical techniques. We show the electrochemical signature of a nitrosoalkane-heme complex that is possibly involved in the mechanism of activation of aliphatic nitro-compounds xenobiotics. A possible heme-mediated electroreductive pathway is proposed. In this work, we also explored the comparative study of the electroreduction of nitromethane using myoglobin, hemin, and iNOSoxy as the electrocatalysts. We discussed the role of the protein shell in the activation process. We also studied four different aliphatic nitroalkanes

Hemoprotein-Mediated Activation of Nitroalkanes

Chemicals and drugs are known to be metabolized mostly by Cytochrome P450 xenobiotic metabolizing enzymes. However, the detailed mechanism of nitro-compounds metabolism is still unclear. The activation of nitro-xenobiotics by heme-P450 enzymes is a potential explanation for the origin of nitro-compound carcinogenesis. Investigating the interaction of simple nitro-compounds with redox activity of heme enzymes is therefore critical to explore the mechanism and products of activation. In this study, multiple analytical methods and instrumentations are employed and graphic and simulation software such as Origin® and Digisim® are utilized to quantitatively derive parameters from experimental raw data. This study shows that myoglobin, iron-protoporphyrin-IX (hemin), and the oxygenase domain of inducible nitric oxide synthase (iNOSoxy) act as efficient electrocatalysts for nitroalkane reductions in the surfactant films on pyrolytic graphite electrodes. In the study using myoglobin as a model electrocatalyst for the electroreduction of nitromethane, the catalytic activity is evaluated using Michaelis-Menten kinetics. The apparent Km and the turnover number kcat are derived from non-linear regression of Michaelis-Menten plot using Origin software. The reductive products of catalytic electroreduction of nitromethane are identified by a mass spectrometric method. We also identified a ferrous heme-nitrosomethane as the intermediate in the catalytic process using UV-Vis spectroscopy and electrochemical techniques. We show the electrochemical signature of a nitrosoalkane-heme complex that is possibly involved in the mechanism of activation of aliphatic nitro-compounds xenobiotics. A possible heme-mediated electroreductive pathway is proposed. In this work, we also explored the comparative study of the electroreduction of nitromethane using myoglobin, hemin, and iNOSoxy as the electrocatalysts. We discussed the role of the protein shell in the activation process. We also studied four different aliphatic nitroalkanes

Modulation of the silica sol-gel composition for the promotion of direct electron transfer to encapsulated cytochrome

The direct electron transfer between indium-tin oxide electrodes (ITO) and cytochrome c encapsulated in different sol-gel silica networks was studied. Cyt c@silica modified electrodes were synthesized by a two-step encapsulation method mixing a phosphate buffer solution with dissolved cytochrome c and a silica sol prepared by the alcohol-free sol-gel route. These modified electrodes were characterized by cyclic voltammetry, UV-vis spectroscopy, and in situ UV-vis spectroelectrochemistry. The electrochemical response of encapsulated protein is influenced by the terminal groups of the silica pores. Cyt c does not present electrochemical response in conventional silica (hydroxyl terminated) or phenyl terminated silica. Direct electron transfer to encapsulated cytochrome c and ITO electrodes only takes place when the protein is encapsulated in methyl modified silica networks.We gratefully acknowledge Jesus Yanez and Prof. Jose Miguel Martin-Martinez from the Laboratory of Adhesion and Adhesives (University of Alicante) for their assistance in the measurements of contact angle. We also acknowledge the Financial support from the Spanish Ministerio de Economia y Competitividad and FEDER y Ciencia (MAT2010-15273), Generalitat Valenciana (PROMETEO2013/038), and the Fundacion Ramon Areces (CIVP16A1821). Alonso Gamero-Quijano is grateful to Generalitat Valenciana (Santiago Grisolia Program) for the funding of his research fellowship.Gamero-Quijano, A.; Huerta, F.; Morallón, E.; Montilla, F. (2014). Modulation of the silica sol-gel composition for the promotion of direct electron transfer to encapsulated cytochrome. Langmuir. 30(34):10531-10538. https://doi.org/10.1021/la5023517S1053110538303

Electrocatalysis by heme enzymes—applications in biosensing

Funding Information: The APC was funded by TIMB3 project, European Union's Horizon 2020 Research and Innovation Program grant agreement No 810856. Funding Information: Acknowledgments: We acknowledge the support from Project LISBOA-01-0145-FEDER-007660 (Microbiologia Molecular, Estrutural e Celular) funded by FEDER funds through COMPETE 2020-Programa Operacional Competitividade e Internacionalização (POCI); from FCT—Fundação para a Ciência e a Tecnologia (PTDC/BIA-BFS/31026/2017 and 2020.05017.BD) and from the European Union's Horizon 2020 Research and Innovation Program, through TIMB3 and B-LigZymes projects (grant agreements No 810856 and 824017, respectively). We thank Edilson Galdino for critical reading of the manuscript and helpful discussions. Funding Information: Funding: The APC was funded by TIMB3 project, European Union's Horizon 2020 Research and Innovation Program grant agreement No 810856. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.Heme proteins take part in a number of fundamental biological processes, including oxygen transport and storage, electron transfer, catalysis and signal transduction. The redox chemistry of the heme iron and the biochemical diversity of heme proteins have led to the development of a plethora of biotechnological applications. This work focuses on biosensing devices based on heme proteins, in which they are electronically coupled to an electrode and their activity is determined through the measurement of catalytic currents in the presence of substrate, i.e., the target analyte of the biosensor. After an overview of the main concepts of amperometric biosensors, we address transduction schemes, protein immobilization strategies, and the performance of devices that explore reactions of heme biocatalysts, including peroxidase, cytochrome P450, catalase, nitrite reductase, cytochrome c oxidase, cytochrome c and derived microperoxidases, hemoglobin, and myoglobin. We further discuss how structural information about immobilized heme proteins can lead to rational design of biosensing devices, ensuring insights into their efficiency and long-term stability.publishersversionpublishe

Hemoprotein-Mediated Activation of Nitroalkanes

Chemicals and drugs are known to be metabolized mostly by Cytochrome P450 xenobiotic metabolizing enzymes. However, the detailed mechanism of nitro-compounds metabolism is still unclear. The activation of nitro-xenobiotics by heme-P450 enzymes is a potential explanation for the origin of nitro-compound carcinogenesis. Investigating the interaction of simple nitro-compounds with redox activity of heme enzymes is therefore critical to explore the mechanism and products of activation. In this study, multiple analytical methods and instrumentations are employed and graphic and simulation software such as Origin® and Digisim® are utilized to quantitatively derive parameters from experimental raw data. This study shows that myoglobin, iron-protoporphyrin-IX (hemin), and the oxygenase domain of inducible nitric oxide synthase (iNOSoxy) act as efficient electrocatalysts for nitroalkane reductions in the surfactant films on pyrolytic graphite electrodes. In the study using myoglobin as a model electrocatalyst for the electroreduction of nitromethane, the catalytic activity is evaluated using Michaelis-Menten kinetics. The apparent Km and the turnover number kcat are derived from non-linear regression of Michaelis-Menten plot using Origin software. The reductive products of catalytic electroreduction of nitromethane are identified by a mass spectrometric method. We also identified a ferrous heme-nitrosomethane as the intermediate in the catalytic process using UV-Vis spectroscopy and electrochemical techniques. We show the electrochemical signature of a nitrosoalkane-heme complex that is possibly involved in the mechanism of activation of aliphatic nitro-compounds xenobiotics. A possible heme-mediated electroreductive pathway is proposed. In this work, we also explored the comparative study of the electroreduction of nitromethane using myoglobin, hemin, and iNOSoxy as the electrocatalysts. We discussed the role of the protein shell in the activation process. We also studied four different aliphatic nitroalkanes