▪ Abstract Proton-coupled electron transfer (PCET) is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues. We review several are...

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Proton-Coupled Electron Transfer

Traditional physicochemical and biological techniques, as well as advanced oxidation processes (AOPs), are often inadequate, ineffective, or expensive for industrial water reclamation. Within this context, the electrochemical technologies have found a niche where they can become dominant in the near future, especially for the abatement of biorefractory substances. In this critical review, some of the most promising electrochemical tools for the treatment of wastewater contaminated by organic pollutants are discussed in detail with the following goals: (1) to present the fundamental aspects of the selected processes; (2) to discuss the effect of both the main operating parameters and the reactor design on their performance; (3) to critically evaluate their advantages and disadvantages; and (4) to forecast the prospect of their utilization on an applicable scale by identifying the key points to be further investigated. The review is focused on the direct electrochemical oxidation, the indirect electrochemical oxidation mediated by electrogenerated active chlorine, and the coupling between anodic and cathodic processes. The last part of the review is devoted to the critical assessment of the reactors that can be used to put these technologies into practice.

Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review.

Laboratoire de Génie Enzymatique et Biomoléculaire, Institut de Chimie et Biochimie Moléculaires et Supramoléculaires, 43 Boulevard du 11 Novembre 1918, Villeurbanne F-69622, France, UMR5246, Centre National de La Recherche Scientifque, Villeurbanne F-69622, France, Université de Lyon, Lyon F-69622, France, Université Lyon 1, Lyon F-69622, France, Institut National des Sciences Appliquées de Lyon, EÄ cole d’Ingénieurs, Villeurbanne F-69621, France, and EÄ cole Supérieure Chimie Physique EÄ lectronique de Lyon, Villeurbanne F-69616, France

DNA biosensors and microarrays.

Publisher Summary The electroactivity of nucleic acids was discovered several years ago. It was shown that at mercury electrodes, adenine and cytosine were reduced in ssDNA while guanine produced an anodic signal due to the oxidation of guanine reduction product. The DNA signals at mercury electrodes are highly sensitive to changes in DNA structure due to DNA denaturation and renaturation, as well as to minor structural changes resulting from DNA premelting and DNA damage. The changes in DNA structure are reflected not only by the DNA faradaic responses but also by non-faradaic signals due to adsorption/desorption of DNA. Several interesting principles have been used in the development of the DNA sensors—such as amplified electrochemical analysis, investigation of charge transport, and tracing of changes in conformation of DNA. The s ensors for DNA hybridization and DNA damage lead the field of the electrochemistry of nucleic acids. The chapter briefly summarizes some properties of the elimination voltammetry with linear scan (EVLS) method. Oscillographic polarography, at controlled alternating current, was used in the electrochemical analysis of nucleic acids.

Electrochemistry of nucleic acids.

The coupling between electron and proton transfers has a long experimental and theoretical history in chemistry and biochemistry. To take just one example, the fact that acceptance of an electron triggers the addition of an acid or the removal of a base and vice versa for oxidations towers over all understanding of organic electrochemistry. Protoncoupled electron transfer (PCET) reactions also play a critical role in a wide range of biological processes, including enzyme reactions, photosynthesis, and respiration. A recent impressive review describes PCET reactions and phenomena. PCET is employed here as a general term for reactions in which both an electron and a proton are transferred, either in two separate steps or in a single step. Reactions in which the electron and proton transfer between the same donor and acceptor, that is, hydrogen atom transfer, are, of course, not considered here because we consider electrochemical PCET reactions in which electrons are flowing into or from an electrode while protons are transferred between acid and base. Molecular electrochemistry, through nondestructive techniques such as cyclic voltammetry, has proved to be very useful in characterizing electron transfers and deciphering mechanisms in which chemical reactions are associated with electron transfer. Therefore, it has been a convenient tool for the mechanistic study of reactions in which electron transfer is coupled to proton transfer, that is, in which an electron leaves or enters an electrode while a proton is transferred from or to the redox species. Until recently, PCET has been mostly thought of as stepwise electron and proton transfer (ET-PT or PT-ET). We thus review in an initial section (section 2) the analysis of such stepwise mechanisms both in aprotic media and in water. In aprotic media, * E-mail address: cyrille.costentin@univ-paris-diderot.fr. Cyrille Costentin was born in Normandy, France, in 1972. He received his undergraduate education at Ecole Normale Superieure (Cachan, France) and pursued his graduate studies under the guidance of Prof. Jean-Michel Saveant and Dr. Philippe Hapiot at the University of ParisDiderot (Paris 7), where he received his Ph.D. in 2000. After a year as a postdoctoral fellow at the University of Rochester, working with Prof. J. P. Dinnocenzo, he joined the faculty at the University of Paris-Diderot as an associate professor. He was promoted to professor in 2007. His interests include mechanisms and reactivity in electron transfer chemistry with particular recent emphasis on electrochemical and theoretical approaches to proton-coupled electron transfer processes. Chem. Rev. 2008, 108, 2145–2179 2145

Electrochemical Approach to the Mechanistic Study of Proton-Coupled Electron Transfer

The reduction mechanism of aromatic nitro compounds in aqueous medium

Performance of interdigitated nanoelectrodes for electrochemical DNA biosensor

The development of biosensors based on DNA hybridization requires a more precise knowledge of the thermodynamics of the hybridization at a solid interface. In particular, the selectivity of hybridization can be affected by a lot of parameters such as the single-strand (ss)DNA density, the pH, the ionic strength or the temperature. The melting temperature, Tm, is in part a function of the ionic strength and of the temperature and therefore provides a useful variable in the control of the selectivity and sensitivity of a DNA chip. The electrochemical technique has been used to determine the Tm values when the probe is tethered by a DNA self-assembled monolayer (SAM). We have built a special thin layer cell, which allows the recording of the cyclic voltammogram under controlled temperature conditions. Tm has been determined by recording the thermogram (current versus temperature) of a redox indicator on a double-stranded hybrid (dsDNA) modified electrode and comparison with the corresponding ssDNA response. Tm of supported DNA varies linearly with the ionic strength. The stability of the SAMs has been considered and comparison between Tm in solution and on a solid support has been discussed.

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Direct measurement of the melting temperature of supported DNA by electrochemical method

https://hal.archives-ouvertes.fr/hal-00376258/document

DNA nanofilm thickness measurement on microarray in air and in liquid using an atomic force microscope.

β-Aminobutyric acid (BABA) is a nonprotein amino acid inducing resistance in many different plant species against a wide range of abiotic and biotic stresses. Nevertheless, how BABA primes plant natural defense reactions remains poorly understood. Based on its structure, we hypothesized and confirmed that BABA is able to chelate iron (Fe) in vitro. In vivo, we showed that it led to a transient Fe deficiency response in Arabidopsis thaliana plants exemplified by a reduction of ferritin accumulation and disturbances in the expression of genes related to Fe homeostasis. This response was not correlated to changes in Fe concentrations, suggesting that BABA affects the availability or the distribution of Fe rather than its assimilation. The phenotype of BABA-treated plants was similar to those of plants cultivated in Fe-deficient conditions. A metabolomic analysis indicated that both BABA and Fe deficiency induced the accumulation of common metabolites, including p-coumaroylagmatine, a metabolite previously shown to be synthesized in several plant species facing pathogen attack. Finally, we showed that the protective effect induced by BABA against Botrytis cinerea was mimicked by Fe deficiency. In conclusion, the Fe deficiency response caused by BABA could bring the plant to a defense-ready state, participating in the plant resistance against the pathogens.

https://apsjournals.apsnet.org/doi/pdf/10.1094/MPMI-05-14-0142-R

Rita Meunier-Prest

Papers

The reduction mechanism of aromatic nitro compounds in aqueous medium

Performance of interdigitated nanoelectrodes for electrochemical DNA biosensor

Direct measurement of the melting temperature of supported DNA by electrochemical method

DNA nanofilm thickness measurement on microarray in air and in liquid using an atomic force microscope.

β-Aminobutyric acid (BABA)-induced resistance in Arabidopsis thaliana: link with iron homeostasis.