Electrochemical Sensors, Biosensors and their Biomedical Applications

Xueji Zhang,Huangxian Ju,Joseph Wang

• Publisher: Academic Press
• Year: 2011
• ISBN:
  9780080554891
• Topic: Scienze biologiche
• Subtopic: Biofisica

This book broadly reviews the modem techniques and significant applications of chemical sensors and biosensors. Chapters are written by experts in the field – including Professor Joseph Wang, the most cited scientist in the world and renowned expert on sensor science who is also co-editor. Each chapter provides technical details beyond the level found in typical journal articles, and explores the application of chemical sensors and biosensors to a significant problem in biomedical science, also providing a prospectus for the future.This book compiles the expert knowledge of many specialists in the construction and use of chemical sensors and biosensors including nitric oxide sensors, glucose sensors, DNA sensors, hydrogen sulfide sensors, oxygen sensors, superoxide sensors, immuno sensors, lab on chip, implatable microsensors, et al. Emphasis is laid on practical problems, ranging from chemical application to biomedical monitoring and from in vitro to in vivo, from single cell to animal to human measurement. This provides the unique opportunity of exchanging and combining the expertise of otherwise apparently unrelated disciplines of chemistry, biological engineering, and electronic engineering, medical, physiological.

• Provides user-oriented guidelines for the proper choice and application of new chemical sensors and biosensors
• Details new methodological advancements related to and correlated with the measurement of interested species in biomedical samples
• Contains many case studies to illustrate the range of application and importance of the chemical sensors and biosensors

CHAPTER 1

Nitric oxide (NO) electrochemical sensors

Xueji Zhang

Publisher Summary

This chapter focuses on nitric oxide (NO) electrochemical sensors. Electrochemical (amperometric) detection of NO is the only available technique sensitive enough to detect relevant concentrations of NO in real time and in vivo and suffers minimally from potential interfering species such as nitrite, nitrate, dopamine, ascorbate, and L-arginine. As NO electrodes can be made on the micro- and nano-scale, these techniques have the advantage of being able to measure NO concentrations in living systems without any significant effects from electrode insertion. The first described electrochemical NO sensor was based on a classical Clark electrode design, where NO was directly oxidized on the working electrode surface. Surface modified NO sensors incorporate an electrode surface that is modified or treated to increase the selectivity of the sensor for NO and promote catalytic oxidation of NO. In most applications detection limit, sensitivity, selectivity and response time are usually the most important requirements. The sensitivity of an NO sensor is directly proportional to the electrode size and surface status, where an electrode with a small surface area will generally have a lower sensitivity compared to the one with a larger surface area. Selectivity is controlled by the voltage applied between the working and reference electrode (poise voltage), and the selective membrane used for coating the sensor. The response time depends on the electrode and the electronics being used to read out the current. Currently NO electrochemical sensors provide the only means to measure NO continuously, accurately and directly within living tissue without significant damage.

Chapter Outline

1.1. Introduction

1.1.1. Significance of nitric oxide in life science

1.1.2. Methods of measurement of nitric oxide in physiology

1.1.3. Advantages of electrochemical sensors for determination of NO

1.2. Principles of determination of NO by electrochemical sensors

1.3. Fabrication of electrodes for NO determination

1.3.1. Clark type NO electrodes

1.3.2. Modified carbon fiber NO microelectrodes

1.3.3. Integrated NO microelectrodes

1.3.4. Other NO electrodes

1.4. Calibration of NO electrodes

1.4.1. Calibration using an NO standard solution

1.4.2. Calibration based on decomposition of SNAP

1.4.3. Calibration based on chemical generation of NO

1.5. Characterization of NO electrodes

1.5.1. Sensitivity and detection limit

1.5.2. Selectivity

1.5.3. Response time

1.5.4. Effect of temperature and pH on NO electrodes

1.6. Selected applications of NO electrodes

1.7. Concluding remarks and other directions

1.8. Acknowledgments

1.9. References

1.1 INTRODUCTION

1.1.1 Significance of nitric oxide in life science

Nitric oxide (NO) is reported to have been first prepared by the Belgian scientist Jan Baptist van Helmont in about 1620 [1]. The chemical properties of NO were first characterized by Joseph Priestly in 1772. However, until the mid-1980s, NO was regarded as an atmospheric pollutant and bacterial metabolite. Nitric oxide (NO) is a hydrophobic, highly labile free radical that is catalytically produced in biological systems from the reduction of L-arginine by nitric oxide synthase (NOS) to form L-citrulline, which produces NO in the process. In biological systems NO has long been known to play various roles in physiology, pathology and pharmacology [2]. In 1987 NO was identified as being responsible for the physiological actions of endothelium-derived relaxing factor (EDRF) [3]. Since that discovery, NO has been shown to be involved in numerous biological processes such as: vasodilatation and molecular messaging [3]; penile erection [4]; neurotransmission [5, 6]; inhibition of platelet aggregation [7]; blood pressure regulation [8]; immune response [9]; and as a mediator in a wide range of both anti-tumor and anti-microbial activities [10, 11]. In addition, NO has been implicated in a number of diseases including diabetes [12], and Parkinson’s and Alzheimer’s diseases [13]. The importance of NO was confirmed in 1992 when Science magazine declared NO the “Molecule of the Year” and in 1998, F. Furchgott, Louis J. Ignarro, and Ferid Murad were awarded the Nobel Prize in Physiology and Medicine for unraveling the complex nature of this simple molecule. Despite the obvious importance of NO in so many biological processes, less than 10% of the thousands of scientific publications over the last decade dedicated to the field of NO research involve its direct measurement.

1.1.2 Methods of measurement of nitric oxide in physiology

As stated above, NO plays a significant role in a variety of biological processes where its spatial and temporal concentration is of extreme importance. However, the measurement of NO is quite difficult due to its short half-life (≈5 sec) and high reactivity with other biological components such as superoxide, oxygen, thiols, and others. To date, several techniques have been developed for the measurement of NO including: chemiluminescence [14, 15]; Griess method [16]; paramagnetic resonance spectrometry [17]; paramagnetic resonance imaging; spectrophotometry [18]; and bioassay [19]. Each of these techniques has certain benefits associated with it but suffer from poor sensitivity and the need for complex and often expensive experimental apparatus. In addition, the above NO sensing techniques are limited when it comes to continuous monitoring of NO concentration in real time and most importantly in vivo.

1.1.3 Advantages of electrochemical sensors for determination of NO

To date, electrochemical (amperometric) detection of NO is the only available technique sensitive enough to detect relevant concentrations of NO in real time and in vivo and suffers minimally from potential interfering species such as nitrite, nitrate, dopamine, ascorbate, and L-arginine. Also, because electrodes can be made on the micro- and nano-scale these techniques also have the benefit of being able to measure NO concentrations in living systems without any significant effects from electrode insertion.

The first amperometric NO electrode used for direct measurement was described in 1990 [20]. In 1992, the first commercial NO sensor system was developed. Over subsequent years a range of highly specialized and sensitive NO electrodes have been developed offering detection limits for NO ranging from below 1 nM up to 100 μM [21]. Most recently, a unique range of high sensitivity NO sensors based on a membrane coated activated carbon microelectrode with diameters ranging from 200 μm down to 100 nm have been developed by this lab. These electrodes exhibit superior performance during NO measurement and feature a detection limit of less than 0.1 nM NO.

1.2 PRINCIPLES OF DETERMINATION OF NO BY ELECTROCHEMICAL SENSORS

NO can be oxidized or reduced on an electrode surface. Since the reduction potential of NO is close to that of oxygen which causes huge interference NO measurement, therefore, usually oxidation of NO is used for measurement of NO. NO oxidation on solid electrodes proceeds via an “EC mechanism” electrochemical reaction [22] followed by chemical reaction [23]. First, one-electron transfer from the NO molecule to the electrode occurred and resulted in the formation of a cation:

NO — e⁻ → NO⁺ (1)

NO⁺ is immediately, irreversibly c...

Table of contents

• Cover image
• Title page
• Table of Contents
• LIST OF CONTRIBUTORS
• PREFACE
• Chapter 1: Nitric oxide (NO) electrochemical sensors
• Chapter 2: Biosensors for pesticides
• Chapter 3: Electrochemical glucose biosensors
• Chapter 4: New trends in ion-selective electrodes
• Chapter 5: Recent developments in electrochemical immunoassays and immunosensors
• Chapter 6: Superoxide electrochemical sensors and biosensors: principles, development and applications
• Chapter 7: Detection of charged macromolecules by means of field-effect devices (FEDs): possibilities and limitations
• Chapter 8: Electrochemical sensors for the determination of hydrogen sulfide production in biological samples
• Chapter 9: Aspects of recent development of immunosensors
• Chapter 10: Microelectrodes for in-vivo determination of pH
• Chapter 11: Biochips – fundamentals and applications
• Chapter 12: Powering fuel cells through biocatalysis
• Chapter 13: Chemical and biological sensors based on electroactive inorganic polycrystals
• Chapter 14: Nanoparticle-based biosensors and bioassays
• Chapter 15: Electrochemical sensors based on carbon nanotubes
• Chapter 16: Biosensors based on immobilization of biomolecules in sol-gel matrices
• Chapter 17: Biosensors based on direct electron transfer of protein
• Index