Professor Joseph S. Beckman recently unveiled some lesser known facts about his seminal work on peroxynitrite: “For over a year, our work had been rejected after lengthy review times by Science, Nature and the Journal of Biological Chemistry. In contrast, the editors of Archives allowed us to publish a series of five papers that established peroxynitrite as a biological oxidant, showed how tyrosine nitration can be used to quantify peroxynitrite production and demonstrated that peroxynitrite was quite toxic to bacteria.” (Arch. Biochem. Biophys., 2009, 484, 114). It is perhaps interesting to mention that this ground-breaking paper has now garnered over 1200 citations. This is indeed remarkable for a paper initially judged to be “not of sufficient interest for the readers.”
As an indication of the excitement produced by this discovery, the five most cited peroxynitrite articles garnered over 14000 citations, as illustrated in Figure 1.
Although the peroxynitrite lifetime is a fraction of a second at physiological pH, it can damage a wide array of molecular components in cells, including DNA and proteins, due to its intrinsic high nitrating properties and surrogate oxidative effects through other radical-generating molecules such as carbon dioxide. Furthermore, abnormal levels of peroxynitrite are clinically correlated with pathogenic effects, including neurodegenerative, cardiovascular or chronic inflammatory diseases, and diabetes complications.
The establishment of peroxynitrite as a culprit in many devastating diseases brings an urgent need and great interest to develop specific detection and quantification tools. Thus the main objectives of this tome are to critically discuss, arguably for the first time in one book, the challenges and latest advancements in peroxynitrite quantification in biological media.
In Chapter 1, Willem H. Koppenol (from the Institute of Inorganic Chemistry, Swiss Federal Institute of Technology, Zürich, Switzerland) introduces the readers to peroxynitrite basics. When it became clear in the early 1990s that peroxynitrite is biologically significant, Willem Koppenol with Joseph Beckman and others (W. H. Koppenol, J. J. Moreno, W. A. Pryor, H. Ischiropoulos and J. S. Beckman, Chem. Res. Toxicol., 1992, 5, 834) reviewed its thermodynamic and kinetic properties. This first part of the book outlines what is still relevant and discusses some of the important aspects that have evolved since then.
Chapter 2 by Sabine Borgmann (from the Fakultät für Chemie und Biochemie, Ruhr-Universität, Bochum, Germany) highlights the complex chemical nature of peroxynitrite for biologists and immunologists, explains the biological impact and complexity of peroxynitrite in biological matrices for chemists and offers guided principles for optimizing quantitative assays.
Chapter 3 is by Mekki Bayachou and colleagues (from the Department of Chemistry, Cleveland State University, and Department of Pathology, Lerner Research Institute, The Cleveland Clinic, Cleveland, USA). This chapter reviews the methods of peroxynitrite synthesis or generation in situ. The advantages and drawbacks of the various methods are discussed in the context of the use of prepared authentic peroxynitrite samples in the development and validation of sensors and probes.
Chapter 4 is by Sabine Szunerits and Rabah Boukherroub (from the Institut d’Electronique, Microélectronique et de Nanotechnologie, University Lille 1, Villeneuve d’Ascq, France) with Serban Peteu (from the Chemical Engineering and Materials Science Department, Michigan State University, USA). It explores the state of the art in the development and use of peroxynitrite sensitive matrices for electrochemical sensing. The electrochemical methods will be further discussed in Chapters 5 to 9.
Chapter 5 by Sophie Griveau and Fethi Bedioui (from the Unité de Technologies Chimiques et Biologiques pour la Santé, Université Paris Descartes, Paris, France) outlines the challenges and perspectives of electrochemical detection schemes for peroxynitrite in biological solutions.
This is followed by the contribution of Christian Amatore, Manon Guille-Collignon and Fréderic Lemaitre (from the Ecole Normale Supérieure, Paris, France). Their Chapter 6 deals with real-time monitoring of peroxynitrite by stimulation of macrophages with ultramicroelectrodes. This unique configuration involving platinized carbon fiber ultramicroelectrodes is of particularly great interest since it allows one to quantify in real time the very harmful and unstable peroxynitrite anion within the oxidative burst at the single cell level.
Many of these species interfere with fluorescence and electrochemical detection methods for peroxynitrite. Therefore, to better understand the role of peroxynitrite in situ, a separation method to isolate peroxynitrite from potential interferences is necessary. Chapter 7 by Susan Lunte, Joseph Siegel, Richard de Campos, Dulan Gunasekara (from the Ralph N. Adams Institute for Bioanalytical Chemistry, University of Kansas, USA), and José da Silva (from the Chemistry Institute, State University of Campinas, São Paulo, Brazil) reviews the electrophoretic methods developed to separate and subsequently detect peroxynitrite as well as its metabolites and degradation products.
Chapter 8 by R. Mark Worden, Ying Liu and Serban Peteu (from the department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan, USA) investigates peroxynitrite–biomembrane interactions using biomimetic interfaces. The mechanisms by which peroxynitrite damages membrane lipids are reviewed and the biomimetic interface platforms and characterization methods are critically discussed. Furthermore, a novel application is proposed to measure the effect of peroxynitrite exposure on biomembrane electrochemical resistance.
In Chapter 9, Serban Peteu and co-workers from the Institut d′Electronique, Microélectronique et de Nanotechnologie, Lille, France (Sabine Szunerits and Rabah Boukherroub) and from Bucharest, Romania (Alina Vasilescu, International Centre for Biodynamics; Valentina Dinca, Mihaela Filipescu, Laurentiu Rosen, Maria Dinescu, the National Institute of Laser, Plasma and Radiation Physics; and Ioana S. Hosu, the National Institute of Chemistry) highlight recent approaches to enhance the selectivity and sensitivity of peroxynitrite detection.
The next two chapters deal with new optical methods for peroxynitrite detection, as these have grown exponentially in the last 5 years. Chapter 10 by Zhijie Chen, Tan Truong and Hui-wang Ai (from the Department of Chemistry and the Cell, Molecular and Developmental Biology Graduate Program, University of California Riverside, USA) outlines recent achievements in the use of fluorescent probes for the detection of peroxynitrite. Indeed, among the various methods for peroxynitrite detection in biological media, fluorescent probes remain one of the most efficient approaches, owing to their sensitivity and specificity for peroxynitrite in live cells.
Chapter 11 by Peng Li and Keli Han (from the State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, China) reports on the use of reversible near-infrared fluorescent probes for peroxynitrite monitoring. The design, synthesis, characterization and imaging applications of cyanine-based, selenium–tellurium modulated fluorescent probes is also described.
What Does the Future Hold for Peroxynitrite?
One thing seems certain: the interest to selectively detect peroxynitrite in biological media will continue, as it comes at least in part from its involvement in the pathophysiology of inflammation, cardiovascular disease, neurodegeneration and diabetes, to name a few. The authors themselves already offer their own outlook in their chapters. Several trends have been revealed in the detection of peroxynitrite and associated nitro-oxidative species. Microsensor arrays and other biomimetic platforms are urgently needed to simultaneously detect multiple analytes in real time, at the cell or tissue level. By coupling several detection techniques, such as electrochemical and fluorescence, one can shed light and extract valuable information on peroxynitrite dynamics with enhanced sensitivity and selectivity.
For in vivo applications, fluorescent imaging frequently lacks good spatial resolution due to limited penetration depth in animal tissue. The exploration of photoacoustic (PA) probes, ensuring highly specific molecular imaging with unprecedented performance, from millimeters to centimeters of tissue with resolutions in the 20–200 µm range is a promising development in this direction. The principle of PA probes is based on the generation of acoustic waves following the absorption of ultrashort light pulses allowing imaging beyond the optical diffusion limit by integrating optical excitation with ultrasonic detection. Semiconducting polymer nanoparticles (SPN) were introduced as a new class of near-infrared photoacoustic contrast agents for in vivo PA molecular imaging of peroxynitrite (K. Pu, A. J. Shuhendler, J. V. Jokerst, J. Mei, S. S. Gambhir, Z. Bao and J. Rao, Nature Nanotechnol., 2014, 9, 233).
Other very recent efforts have targeted real-time imaging of oxidative and nitrosative stress in whole animals, using polymeric nanosensors, integrating fluorescence resonance energy transfer (FRET) and chemiluminescence resonance energy transfer (CRET). Peroxynitrite and other reactive nitro-oxidative species can be detected in a dose-dependent manner in the liver of mice within minutes of drug administration, preceding histological changes, protein nitration or DNA strand break induction (A. J. Shuhendler, K. Pu, L. Cui, J. P. Uetrecht and J. Rao, Nature Biotechnol., 2014, 12, 373).
In conclusion, there is no shortage of new and innovative detection methods and it will be exciting to follow their future progress in monitoring peroxynitrite dynamics in vivo. One goal is to discriminate between the physiological and pathological levels of peroxynitrite in different organs to facilitate the design of better therapies to counteract the nitro-oxidative effects of this species.
As book editors, we are thankful to the Royal Society of Chemistry who embraced our project and put their prestige behind it. We were also lucky to involve so many eminent authors to share their knowledge and know-how. With them all, we hope that this content will be of interest for researchers, students and anyone else with an interest in the quickly evolving peroxynitrite story. We trust that you will enjoy your reading.
Serban F. Peteu