Biosensors Nanotechnology

Ashutosh Tiwari, Anthony P. F. Turner, Ashutosh Tiwari, Anthony P. F. Turner

• Publisher: Wiley-Scrivener
• Year: 2014
• Print ISBN: 9781118773512
• eBook ISBN: 9781118773819
• Edition: 1
• Topic: Technologie et ingénierie
• Subtopic: Science des matériaux

This book provides detailed reviews of a range of nanostructures used in the construction of biosensors as well as the applications of these biosensor nanotechnologies in the biological, chemical, and environmental monitoring fields

Biological sensing is a fundamental tool for understanding living systems, but also finds practical application in medicine, drug discovery, process control, food safety, environmental monitoring, defense, and personal security. Moreover, a deeper understanding of the bio/electronic interface leads us towards new horizons in areas such as bionics, power generation, and computing. Advances in telecommunications, expert systems, and distributed diagnostics prompt us to question the current ways we deliver healthcare, while robust industrial sensors enable new paradigms in R&D and production.

Despite these advances, there is a glaring absence of suitably robust and convenient sensors for body chemistries. This book examines some of the emerging technologies that are fueling scientific discovery and underpinning new products to enhance the length and quality of our lives.

The 14 chapters written by leading experts cover such topics as:

• ZnO and graphene microelectrode applications in biosensing
• Assembly of polymers/metal nanoparticles
• Gold nanoparticle-based electrochemical biosensors
• Impedimetric DNA sensing employing nanomaterials
• Graphene and carbon nanotube-based biosensors
• Computational nanochemistry study of the BFPF green fluorescent protein chromophore
• Biosynthesis of metal nanoparticles
• Bioconjugated-nanoporous gold films in electrochemical biosensors
• The combination of molecular imprinting and nanotechnology
• Principles and properties of multiferroics and ceramics

Part 1

NEW MATERIALS AND METHODS

Chapter 1

ZnO and Graphene Microelectrode Applications in Biosensing

Susana Campuzano¹, María Pedrero¹, Georgia-Paraskevi Nikoleli², José M. Pingarrón¹, Dimitrios P. Nikolelis^*,3, Nikolaos Tzamtzis² and Vasillios N. Psychoyios²

¹Department of Analytical Chemistry, Faculty of Chemical Sciences, Complutense University of Madrid, Madrid, Spain

²Laboratory of Inorganic and Analytical Chemistry, School of Chemical Engineering, Dept. 1, Chemical Sciences, National Technical University of Athens, Athens, Greece

³Laboratory of Environmental Chemistry, Department of Chemistry, University of Athens, Athens, Greece

*Corresponding author: [email protected]

Abstract

Graphene nanomaterials have been the focus of tremendous attention not only in the field of basic research but also in technological applications, owing to their unique physicochemical dimensions such as good sensing ability, and excellent mechanical, thermal and electrical properties. On the other hand, ZnO nanomaterials have attracted considerable interest in relation to sensors due to their many advantages, including large surface-to-volume ratio, excellent biological compatibility, high electron-transfer rates, non-toxicity and biosafety. The development of biosensors can potentially be an interesting application for the utilization of these nanomaterials tremendously large surface-area-to-volume ratio, which is a dominating and promising parameter with the potential to solve biocompatibility and biofouling problems. The present chapter describes recent examples in the development of miniaturized amperometric and potentiometric biosensors by integrating enzymes and one of these two nanomaterials. The latest advances relating to the application of these biosensors to rapidly detect biomedically relevant substrates such as glucose, urea, uric acid, cholesterol, etc., with enormous prospects in clinical medicine applications are reviewed throughout. The presented biosensors exhibit good reproducibility, reusability, selectivity, rapid response times, long shelf life and high sensitivity, and do not suffer from interference by coexisting oxidable substances. These electrochemical nanobiosensors prepared through the integration of biomolecules with graphene or ZnO nanostructures have demonstrated that, besides enhancing the biosensing capabilities compared with conventional platforms, bring out new approaches such as miniaturization, reagentless biosensing and single-molecule detection. This chapter highlights the significant milestones achieved and further elucidates the emerging future prospects in this area.

Keywords: Biosensors, electroanalysis, ZnO and graphene microstructures, microelectrodes

1.1 Biosensors Based on Nanostructured Materials

Biosensors have become important and practical tools in the field of healthcare, chemical and biological analysis, environmental monitoring, food safety control, and homeland security. The performance of biosensors depends on their components, among which the matrix material, i.e., the layer between the recognition layer of biomolecule and transducer, plays a crucial role in defining the stability, sensitivity and shelf life of a biosensor [1]. Among biosensors, electrochemical ones are of particular interest due to several combined advantages such as low detection limits, short response times, long-term stability, power requirements, low cost, ease of operation, and miniaturization capability. A current goal for these types of biosensors is their translation to point-of-care diagnostic devices. Much effort has been put into improving key performance parameters, such as sensitivity, specificity, recognition rates, stability and multiplexing capabilities for parallel recognition, to allow this possibility.

The emergence of nanotechnology has opened new horizons for electrochemical biosensors. It is believed that highly sensitive and selective biosensors can be realized through the integration of biomolecules and nanomaterial-based sensor platforms. Over the last fifteen years, efforts have focused on the use of nanotechnology to develop nanostructured materials (e.g., graphene and ZnO nanowires, nanotubes, nanowalls and nanorods) as biomolecule immobilizing matrices/supports to improve electrochemical detection [2]. Nanoscale structures like these offer many unique features and show great promise for faster response and higher sensitivity at the device interface than planar sensor configurations. Their nanometer dimensions, being in the scale of the target analyte, show an increased sensing surface and strong binding properties, thus allowing a higher sensitivity. The interest in developing these nanostructures for biosensing applications has resulted from the development of new synthesis methods and improved characterization techniques, allowing for new functionalities to be created [2].

Because of their interesting advantages among the nanomaterials that have been developed, this chapter describes the increasing application of graphene and ZnO nanostructures to the fabrication of highly sensitive electrochemical biosensors. Latest advances (from 2004 onwards) in electrochemical biosensors based on the distinct advantages and practical sensing utility of these two nanostructured materials are discussed and illustrated in the following sections in connection to enzyme electrodes for the determination of analytes of clinical relevance. Although several strategies have been described for using these nanomaterials in such bioaffinity and biocatalytic sensing [3, 4], both for amplification tagging or modifying electrode transducers, this chapter will focus only on their applications as surface modifiers. The broad capabilities of such modern nanomaterials-based bioelectrodes for biocatalytic electrochemical detection (mainly amperometric and potentiometric) of numerous biologically important analytes, and for other bioelectronic affinity assays (e.g., DNA hybridization assays), will be discussed along with future prospects and challenges.

1.2 Graphene Nanomaterials Used in Electrochemical Biosensor Fabrication

Graphene and its derived structures (graphene oxide, graphene platelets, graphene nanoflakes) have become popular materials for fabricating electrode matrixes for sensing and biosensing [5]. Graphene is the mother of all graphitic forms, including zero-dimensional fullerenes, one-dimensional carbon nanotubes, and three-dimensional graphite [6].

Graphene, defined as a single-layer two-dimensional sp²-hybridized carbon, is currently, without any doubt, the most intensively studied material. This single-atom-thick sheet of carbon atoms arrayed in a honeycomb pattern is the world’s thinnest, strongest, and stiffest material, as well as an excellent conductor of both heat and electricity [7]. It is often categorized by the number of stacked layers: single layer, few layer (2–10 layers), and multilayer, which is also known as thin graphite. Ideally, for graphene to preserve its distinct properties, its use should be narrowed to single- or few-layer morphologies [5].

Graphene’s considerable attention as a next generation electronic material derives from its unique electronic, optical, mechanical, thermal, and electrochemical properties [5]. It being electronically a very good low-noise material, graphene can be employed in the achievement of molecular sensing [8].

Graphene is attractive for electrochemistry because it is a conductive yet transparent material, with a low cost and low environmental impact, a wide electrochemical potential window, low electrical resistance in comparison to glassy carbon (GC), atomic thickness and two well defined redox peaks linearly aligned with the square root of the scan rate magnitude, suggesting that its redox processes are primarily diffusion controlled. Peak-to-peak values under cyclic voltammetry are low, suggesting rapid electron transfer kinetics, and its apparent electron transfer rate is orders of magnitude higher than that of GC. This rate of electron transfer has been shown to be surface dependent and can be increased significantly by the creation of specific surface functional groups [8]. The high density of edge-plane defect sites on graphene provides multiple electrochemically active sites. Its entire volume is exposed to the surroundings due to its 2D structure, making it very efficient in detecting adsorbed molecules. Graphene-based electrodes also exhibit high enzyme loading due to their high surface area. This, in turn, can facilitate high sensitivity, excellent electron transfer promoting ability for some enzymes, and excellent catalytic behavior towards many biomolecules [8, 9]. Graphene-based devices also possess the required biocompatibility to be amenable for in situ biosensing.

Graphene exhibits the advantages of a large surface area (2,630 m² g⁻¹ for single-layer graphene) similar to that of carbon nanotubes (CNTs), and a small size of each individual unit, also exhibiting some other merits like low cost, two external surfaces, facile fabrication and modification and absence of metallic impurities, which may yield unexpected and uncontrolled electrocatalytic effects and toxicological hazards [5, 8, 9].

It has also been reported that the edges of graphene sheets possess a variety of oxygenated species that can support efficient electrical wiring of the redox centers of several heme-containing metalloproteins to the electrode and also enhance the adsorption and desorption of molecules [8, 9].

Graphene-based nanomaterials can be classified in relation to the method of production. They can be produced by chemical vapor deposition (CVD) growth, by mechanical exfoliation of graphite, or by exfoliation of graphite oxide. Neither CVD-produced graphene nor mechanically exfoliated graphene contain large quantities of defects or functionalities. Bulk quantities of graphene-based nanomaterials are typically prepared by different methods, such as the thermal exfoliation of graphite oxide which leads to a material called thermally reduced graphene (GO) or, for example, sono-assisted exfoliation of graphite oxide to graphene oxide (GO), which can be further reduced chemically or electrochemically. The products are typically referred to as chemically reduced GO (CRGO) or electrochemically reduced GO (ERGO). The TRGO contains large amounts of defects and significantly differs from pristine graphene, which has a perfect honeycomb lattice structure. The GO has a structure that is not fully planar because the sp² carbon network is heavily damaged. It contains large amounts of oxygen-containing groups, which can be beneficial to the functionalization through the action of the biomolecules for biorecognition events during biosensing. Reduced forms of GO have a partly restored sp² lattice but still hold some fraction of oxygen-containing groups [10]. Therefore, one could have a large graphene “toolbox” to choose the right type of graphene for the right application and transduction mechanism [11]. Most of graphene used in electrochemistry is graphene produced from GO chemical/thermal reduction, which is also called functionalized graphene sheets or chemically reduced GO, and usually has abundant structural defects and functional groups which are advantageous for electrochemical applications. It has been demonstrated that ERGO exhibits much better performance for electrochemical applications than CRGO. Moreover, Chua et al. [12] demonstrated that not all graphene materials are beneficial for the detection in lab-on-chip devices. Their findings could provide valuable insights into the future applicability of graphene materials towards practical applications.

The future development of electrochemical graphene-based nanobio-devices should be based on the better understanding of some electrochemical details, such as the role of the defects and oxygen-containing groups at the edges of graphene sheets, the interaction mechanism of biomolecules with graphene surface, and the role of doping heteroatoms in graphene. Furthermore, it is important to remark that novel methods for well-controlled synthesis and processing of graphene should be developed. Although graphene has been synthesized with various strategies, the economical production approach with high yield is still not widely available.

1.3 ZnO Nanostructures Used in the Fabrication of Electrochemical Biosensors

Recently, nanostructured metal oxides (NMOs) based on metals such as zinc, iron, cerium, tin, zirconium, copper, titanium, and nickel, have aroused much interest as immobilizing matrices for the development of improved electrochemical biosensors [13]. They have been found to exhibit interesting nanomorphological, functional biocompatible, non-toxic and catalytic properties, providing an effective surface for biomolecule immobilization with the desired orientation, better conformation and high biological activity, resulting in enhanced biosensing characteristics [13, 14]. The NMOs with desired functionalities and surface charge properties provide interesting platforms for interfacing biorecognition elem...

Table of contents

• Cover
• Half Title page
• Title page
• Copyright page
• Preface
• Part 1: New Materials and Methods
• Part 2: Principals and Prospective
• Part 3: Advanced Structures and Properties
• Index