Advanced Sensor and Detection Materials E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: Advance Materials Series
• Sprache: Englisch

Seitenzahl: 820

Veröffentlichungsjahr: 2014

Beschreibung

Presents a comprehensive and interdisciplinary review of the major cutting-edge technology research areas--especially those on new materials and methods as well as advanced structures and properties--for various sensor and detection devices The development of sensors and detectors at macroscopic or nanometric scale is the driving force stimulating research in sensing materials and technology for accurate detection in solid, liquid, or gas phases; contact or non-contact configurations; or multiple sensing. The emphasis on reduced-scale detection techniques requires the use of new materials and methods. These techniques offer appealing perspectives given by spin crossover organic, inorganic, and composite materials that could be unique for sensor fabrication. The influence of the length, composition, and conformation structure of materials on their properties, and the possibility of adjusting sensing properties by doping or adding the side-groups, are indicative of the starting point of multifarious sensing. The role of intermolecular interactions, polymer and ordered phase formation, as well as behavior under pressure and magnetic and electric fields are also important facts for processing ultra-sensing materials. The 15 chapters written by senior researchers in Advanced Sensor and Detection Materials cover all these subjects and key features under three foci: 1) principals and perspectives, 2) new materials and methods, and 3) advanced structures and properties for various sensor devices.

Leseprobe

Contents

Cover

Half Title page

Title page

Copyright page

Preface

Part 1: Principals and Prospective

Chapter 1: Advances in Sensors’ Nanotechnology

1.1 Introduction

1.2 What is Nanotechnology?

1.3 Significance of Nanotechnology

1.4 Synthesis of Nanostructure

1.5 Advancements in Sensors’ Research Based on Nanotechnology

1.6 Use of Nanoparticles

1.7 Use of Nanowires and Nanotubes

1.8 Use of Porous Silicon

1.9 Use of Self-Assembled Nanostructures

1.10 Receptor-Ligand Nanoarrays

1.11 Characterization of Nanostructures and Nanomaterials

1.12 Commercialization Efforts

1.13 Future Perspectives

References

Chapter 2: Construction of Nanostructures: A Basic Concept Synthesis and Their Applications

2.1 Introduction

2.2 Formation of Zinc Oxide Quantum Dots (ZnO-QDs) and Their Applications

2.3 Needle-Shaped Zinc Oxide Nanostructures and Their Growth Mechanism

2.4 Flower-Shaped Zinc Oxide Nanostructures and Their Growth Mechanism

2.5 Construction of Mixed Shaped Zinc Oxide Nanostructures and Their Growth Mechanicsm

2.6 Summary and Future Directions

References

Chapter 3: The Role of the Shape in the Design of New Nanoparticles

3.1 Introduction

3.2 The Importance of Shape as Nanocarries

3.3 Influence of Shape on Biological Process

3.4 Different Shapes of Polymeric Nanoparticles

3.5 Different Shapes of Non-Polymeric Nanoparticles

3.6 Different Shapes of Polymeric Nanoparticles: Examples

3.7 Another Type of Nanoparticles

Acknowledgments

References

Chapter 4: Molecularly Imprinted Polymer as Advanced Material for Development of Enantioselective Sensing Devices

4.1 Introduction

4.2 Molecularly Imprinted Chiral Polymers

4.3 MIP-Based Chiral Sensing Devices

4.4 Conclusion

References

Chapter 5: Role of Microwave Sintering in the Preparation of Ferrites for High Frequency Applications

5.1 Microwaves in General

5.2 Microwave-Material Interactions

5.3 Microwave Sintering

5.4 Microwave Equipment

5.5 Kitchen Microwave Oven Basic Principle

5.6 Microwave Sintering of Ferrites

5.7 Microwave Sintering of Garnets

5.8 Microwave Sintering of Nanocomposites

References

Part 2: New Materials and Methods

Chapter 6: Mesoporous Silica: Making “Sense” of Sensors

6.1 Introduction to Sensors

6.2 Fundamentals of Humidity Sensors

6.3 Types of Humidity Sensors

6.4 Humidity Sensing Materials

6.5 Issues with Traditional Materials in Sensing Technology

6.6 Introduction to Mesoporous Silica

6.7 M41S Materials

6.8 SBA Materials

6.9 Structure of SBA-15

6.10 Structure Directing Agents of SBA-15

6.11 Factors Affecting Structural Properties and Morphology of SBA-15

6.12 Modification of Mesoporous Silica

6.13 Characterization Techniques for Mesoporous Materials

6.14 Humidity Sensing of SBA-15

6.15 Extended Family of Mesoporous Silica

6.16 Other Applications of SBA-15

6.17 Conclusion

References

Chapter 7: Towards Improving the Functionalities of Porous TiO2-Au/Ag Based Materials

7.1 Porous Nanostructures Based on Tio2 and Au/Ag Nanoparticles for Environmental Applications

7.2 Morphological Particularities of the TiO2-based Aerogels

7.3 Designing the TiO2 Porous Nano-architectures for Multiple Applications

7.4 Evaluating the Photocatalytic Performances of the TiO2-Au/Ag Porous Nanocomposites for Destroying Water Chemical Pollutants

7.5 Testing the Effectiveness of the TiO2-Au/Ag Porous Nanocomposites for Sensing Water Chemical Pollutants by SERS

7.6 In-depth Investigations of the Most Efficient Multifunctional TiO2-Au/Ag Porous Nanocomposites

7.7 Conclusions

Acknowledgments

References

Chapter 8: Ferroelectric Glass-Ceramics

8.1 Introduction

8.2 (Ba1−xSrx)TiO3 [BST] Glass-Ceramics

8.3 Glass-Ceramic System (1–y) BST: y (B2O3: x SiO2)

8.4 Glass-Ceramic System (1−y) BST: y (BaO: Al2O3: 2SiO2)

8.5 Comparision of the Two BST Glass-Ceramic Systems

8.6 Pb(ZrxTi1−x)TiO3[PZT] Glass-Ceramics

References

Chapter 9: NASICON: Synthesis, Structure and Electrical Characterization

9.1 Introduction

9.2 Theretical Survey of Superionic Conduction

9.3 NASICON Synthesis

9.4 NASICON Structure and Properties

9.5 Characterization Techniques

9.6 Experimental Results

9.7 Problems, Applications, and Prospects

9.8 Conclusion

Acknowledgments

References

Chapter 10: Ionic Liquids

10.1 Ionic Liquids: What Are They?

10.2 Historical Background

10.3 Classification of Ionic Liquids

10.4 Properties of Ionic Liquids, Physical and Chemical

10.5 Synthesis Methods of Ionic Liquids

10.6 Characterization of Ionic Liquids

10.7 Major Applications of ILs

10.8 ILs in Organic Transformations

10.9 ILs for Synthesis and Stabilization of Metal Nanoparticles

10.10 Challenges with Ionic Liquids

References

Chapter 11: Dendrimers and Hyperbranched Polymers

11.1 Introduction

11.2 Synthesis of Dendritic Polymers

11.3 Characterization

11.4 Properties

11.5 Applications

11.6 Conclusion

References

Part 3: Advanced Structures and Properties

Chapter 12: Theoretical Investigation of Superconducting State Parameters of Bulk Metallic Glasses

12.1 Introduction

12.2 Computational Methodology

12.3 Results and Discussion

12.4 Conclusions

References

Chapter 13: Macroscopic Polarization and Thermal Conductivity of Binary Wurtzite Nitrides

13.1 Introduction

13.2 The Macroscopic Polarization

13.3 Effective Elastic Constant, C44

13.4 Group Velocity of Phonons

13.5 Phonon Scattering Rates

13.6 Thermal Conductivity of InN

13.7 Summary

References

Chapter 14: Experimental and Theoretical Background to Study Materials

14.1 Quasi-Elastic Light Scattering (Photon Correlation Spectroscopy)1

14.2 Transmission Electron Microscopy (TEM)

14.3 Scanning Electron Microscopy [2]

14.4 X-ray Diffraction (XRD)

14.5 UV-visible Spectroscopy

14.6 FT-IR Spectroscopy

14.7 NMR Spectroscopy

14.8 Mass Spectrometry

14.9 Vibrating Sample Magnetometer

References

Chapter 15: Graphene and Its Nanocomposites for Gas Sensing Applications

15.1 Introduction

15.2 Principles of Chemical Sensing by Conducting Nanocomposite Materials

15.3 Synthesis of Graphene and Its Nanocomposites

15.4 Characterization of Graphene and Its Nanocomposites

15.5 Chemical Sensing of Graphene and Its Nanocomposites

15.6 Conclusion and Future Aspects

Acknowledgements

References

Index

Advanced Sensor and Detection Materials

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Advance Materials Series The Advance Materials Series provides recent advancements of the fascinating field of advanced materials science and technology, particularly in the area of structure, synthesis and processing, characterization, advanced-state properties, and applications. The volumes will cover theoretical and experimental approaches of molecular device materials, biomimetic materials, hybrid-type composite materials, functionalized polymers, superamolecular systems, information- and energy-transfer materials, biobased and biodegradable or environmental friendly materials. Each volume will be devoted to one broad subject and the multidisciplinary aspects will be drawn out in full.

Series Editor: Dr. Ashutosh Tiwari Biosensors and Bioelectronics Centre Linkoping University SE-581 83 Linkoping Sweden E-mail: [email protected]

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Library of Congress Cataloging-in-Publication Data:

ISBN 978-1-118-77348-2

Preface

The development of sensors and detectors at macroscopic or nanometric scale is the driving force stimulating research in sensing materials and technology for accurate detection in solid, liquid or gas phases, contact or non-contact configurations or multiple sensing. The emphasis on reduced-scale detection techniques requires the use of new materials and methods. These techniques offer appealing perspectives given by spin crossover organic, inorganic and composite materials that could be unique for sensor fabrication. The influence of the length, composition and conformation structure of materials on their properties, and the possibility of adjusting sensing properties by doping or adding the side-groups, are indicative of the starting point of multifarious sensing. The role of intermolecular interactions, polymer and ordered phase formation, as well as behavior under pressure and magnetic and electric fields, are also important facts for processing ultra-sensing materials. In this book, we have highlighted the key features which aid in the design of new sensor and detection materials with a special focus on 1) principals and perspectives, 2) new materials and methods and 3) advanced structures and properties for various sensor devices.

Science and technology at the nanometer scale addresses a wide variety of disciplines and applications. The chapter “Advances in Sensors’ Nanotechnology” underlines the significance of nanotechnology in the sensor field and also describes the use of various nanomaterials for the construction of sensing devices for medical diagnostics. In conjuction with this chapter, “Construction of Nanostructures: A Basic Concept Synthesis and Their Applications,” covers the use of various precursors and techniques for the bottom-up synthesis of nanostructures having different morphology, including shape, size and dimensions. A general literature overview and future directions are given for a model ZnO chemistry. In “The Role of the Shape in the Design of New Nanoparticles,” the influence of geometry of the nanoobjects on biological processes is discussed. A particular emphasis is given to improvement in controlled release of drugs using polymeric and nonpolymeric nanomaterials. The chapter entitled “Molecularly imprinted Polymer as Advanced Material for Development of Enantioselective Sensing Devices,” describes a range of molecularly imprinted polymers for chiral recognition of biological molecules. The devices based on enantiodifferentiation, including electrochemical, optical, and piezoelectric sensing, are exemplified.

Highlighted in the chapter, “Role of Microwave Sintering in the Preparation of Ferrites for High Frequency Applications,” is the preparation of nanocrystalline magnetic oxide materials using a microwave sintering method. The application of this method is exemplified for a wide range of mixed ferrite nanoparticles at high frequency applications. In the chapter, “Mesoporous Silica: Making ‘Sense’ of Sensors,” the significance of porous materials is overviewed together with the preparation and surface functionalization methods of oxidic nanomaterials. A particular emphasis is given to silica having interconnected internal porosity at mesoscale for relative humidity sensing applications. Artifical neural network is used for handling complex systems for nonlinear interaction between decisive variables. The chapter “Towards Improving the Functionalities of Porous TiO2-Au/Ag-Based Materials,” describes titanium dioxide aerogels decorated with Au/Ag nanoparticles. The sensing of water chemical pollutants by surface-enhanced Raman scattering of porous nanocomposite materials is discussed. The chapter “Ferroelectric Glass-Ceramics” contains a literature review on the research and development of new materials for various applications, including doping of existing materials as well as processing for improved properties. In the chapter entitled, “NASICON: Synthesis, Structure and Electrical Characterization,” various synthesis methods and characterization of Na super-ionic conductors that have potential for applications in rechargable lithium ion batteries and gas sensors are reported. Problems of synthesis, applications and prospects are also discussed.

In the chapter “Ionic Liquids,” a general introduction to ionic liquids is given along with some historical background. The physical and chemical features of this family of molecules are discussed from environmental and economical perspectives. The chapter entitled “Dendrimers and Hyperbranched Polymers,” highlights the unique features of dentritic macromolecules in general. Their applications associated with molecular structures are overviewed. In the chapter “Theoretical Investigation of Superconducting State Parameters of Bulk Metallic Glasses,” superconductivity in bulk metallic glasses is reported using EMC model potential and H-local field correction functions.

Wurtzide (III-IV) nitrides are direct- and wide-bandgap semiconductors with a wide range of bandgap as well as very high environmental and thermal stability. “Macroscopic Polarization and Thermal Conductivity of Binary Wurtzite Nitrides” describes the effect of spontaneous and piezoelectric polarization on thermal conductivity of binary wurtzide nitrides. The application of ferroelectric glass ceramics in the sensor field is wide and of considerable technological importance due to their rich crystal chemistry and structure-property relationships. The chapter “Experimental and Theoretical Background to Study Materials,” covers the theoretical background of basic tools in experimental characterization of materials, particularly at nanometer scale, including electron scattering, diffraction, microscopy and spectroscopy. The final chapter, “Graphene and Its Nanocomposites for Gas Sensing Applications,” discusses the principles of chemical sensing by conducting nanocomposite materials and the synthesis and characterization of graphene and its nanocomposites.

This book has been written for a large readership including university students and researchers from diverse backgrounds such as sensor and detection science, chemistry, materials science, physics, pharmacy, medical science and biomedical engineering. It can be used not only as a textbook for both undergraduate and graduate students, but also as a review and reference book for researchers in the fields of materials science, device engineering, medical, pharmacy, biotechnology and nanotechnology We hope the chapters of this book will give readers valuable insight into the major research area of Advanced Sensor and Detection Materials, especially the cutting-edge technology on new materials and methods, advanced structures and properties for various sensor and detection devices. The interdisciplinary nature of the topics in this book will help young researchers and senior academicians. The main credit for this book goes to the contributors who have comprehensively written their state-of-the-art chapters.

EditorsAshutosh Tiwari, PhD, DScMustafa M. Demir, PhDApril 2014

Part 1

PRINCIPALS AND PROSPECTIVE

Chapter 1

Advances in Sensors’ Nanotechnology

Ida Tiwari1,* and Manorama Singh2

1Centre of Advanced Study, Department of Chemistry, Banaras Hindu University, Varanasi

2Department of Chemistry, Guru Ghasidas Vishwavidyalaya, Bilaspur (C.G.)

*Corresponding author: [email protected], [email protected]

Abstract

Nowadays, sensors are considered as important instruments available particularly in health care systems, for diagnosis and monitoring of diseases as there has been a strong demand for producing highly sensitive, responsive, selective, and cost-effective sensors. As a result, research emphasis is on developing new sensing materials and technologies to amplify signal of biorecognition event. In this context, the use of nanomaterials for the construction of sensor devices constitutes one of the most exciting approaches. The extremely promising prospects of these devices accrue from the unique properties of nanomaterials. Although different nanomaterials (e.g., carbon nanotubes, nanoparticles, graphene, etc.) are employed for the construction of sensors in different fields, it is in medical diagnostics where maximum application can be made due to enhanced analytical performance with respect to other designs. With the advent of nanotechnology, research is on track to create highly selective, highly sensitive and miniaturized sensors for medical applications. Miniaturized sensors can lead to lower power consumption, reduced weight, and low cost.

Keywords: Nano-materials, diseases, miniaturized sensor, sensitive, medical devices

1.1 Introduction

A sensor is a device that receives and responds to a signal. In other words, a sensor is a device that measures a physical quantity and converts it into a signal, which can be read by an observer or by an instrument. Sensors consist of a recognition element in intimate contact with a signal transducer. Sensors that measure very small changes must have very high sensitivities. Sensors can be divided into electrochemical, optical, mass and thermal sensors based on transducer (cf.figure 1.1).

Figure 1.1 Schematic diagram of the sensor.

In recent years, with the development of nanotechnology, a lot of novel nanomaterials are being fabricated and introduced in the recognition element. Their novel properties are being gradually exposed and the use of nanomaterials for the construction of bio-sensing devices constitutes one of the most exciting approaches. Intensive research efforts have been performed in the field of designing sensors capable of providing better analytical characteristics in terms of sensitivity, selectivity, reliability, ease of fabrication and use, and low cost. The applications of nanomaterials-based (bio)sensors, which include the material science, molecular engineering, chemistry, and biotechnology have advanced greatly. They can markedly improve the sensitivity and specificity of analyte detection, and have great potential in applications such as biomolecular recognition, pathogenic diagnosis, and environment monitoring [1, 2].

This chapter is based on some of the main advances to use nanotechnology in sensors’ fields over the past few years. It explores the application prospects and discusses the various issues and approaches, with the aim of stimulating a broader interest in using nanoparticles, nanotubes, nanowires, and other different nanostructures to develop highly sensitive and successful nanomaterials-based (bio)sensor technology.

1.2 What is Nanotechnology?

The word “Nano” means dwarf in the Greek language. It is used as a prefix for any unit, like a second or a meter, and it means a billionth of that unit. A nanosecond is one billionth of a second and a nanometer is one billionth of a meter—about the length of a few atoms lined up shoulder to shoulder. The simplest definition of nanotechnology is “technology at the nano-scale.” According to the US foresight institute, “nanotechnology is a group of emerging technologies in which the structure of matter is controlled at the nanometer scale to produce novel materials and devices that have useful and unique properties.” It is also possible to define nanotechnology extensively [3].

1.3 Significance of Nanotechnology

Nanostructure science and technology is a broad and interdisciplinary area of research and development activity that has been growing explosively worldwide in the past few years.

“One nanometer is a magical point on the dimensional scale.”

All materials will show the peculiar behavior and change in their properties when they enter into the nano scale. Nanotechnology plays an important role in developing sensors. Sensitivity and other attributes can be improved by using nanomaterials in sensor construction because of their quantum size, mini size and surface effect. Incorporation of nanomaterials into sensors offers increased surface area, more efficient electron transfer from enzyme to electrode, and the ability to include additional catalytic effect.

1.4 Synthesis of Nanostructure

There are two approaches for the synthesis of nanomaterials and nanostructures (cf.figure 1.2). Top-down approach refers to starting with large-scale objects and gradually reducing their dimensions. Bottom-up approach refers to assembling the atom or molecules into smallest nanostructures by carefully controlled chemical reactions [4]. One of the ultimate goals is to precisely position building blocks in a predetermined manner so that each component can be individually addressed in the final assembly [5].

Figure 1.2 Schematic representation of the building up of nanostructures.

1.5 Advancements in Sensors’ Research Based on Nanotechnology

This is an interdisciplinary boundary between materials science and biology. It also provides a productive platform for new scientific and technological development. For the fabrication of an efficient biosensor, the selection of substrate for dispersing the sensing material decides the sensor performance. Various novel advance functional materials (e.g., gold nanoparticles, carbon nanotubes (CNTs), nanoparticles, and mesoporous silica materials, etc.) are being gradually applied to (bio)sensors for medical applications because of their unique physical, chemical, mechanical, magnetic, and optical properties, and they also markedly enhance the sensitivity and specificity of detection. In this chapter, we try to discuss several nanostructures that are currently used in the development of nano-biosensors, molecular sensors, drug delivery [6], tissue regeneration [2, 7], and nano-device fabrication [8].

Nano-biosensors offer a highly sensitive biorecognition device for medical applications, e.g., cancer diagnostics and other diseases, intra-operation pathological testing, proteomics, and system biology, etc. [9]. Drug delivery is a key technology for the realization of nano-medicine, and nanostructured mediated systems play an important role in improving the properties of already existing therapeutic and diagnostic modalities [10, 11]. Nanostructure materials provide high surface to volume ratio, which enhances the stability of drug molecules [12] loading and delivery as well as mass transfer properties of drugs [13].

Here, we will we focus particularly on the properties and role of different nanostructures, i.e., nanoparticles, nanotubes, mesoporous silica, etc., in various sensor biomedical technologies.

1.6 Use of Nanoparticles

Nanoparticles have numerous possible applications in sensors. These nanoparticles play different roles in different electrochemical sensing systems based on their unique properties, e.g., in immobilization of molecules, catalysis of electrochemical reactions, enhancement of electron transfer, labeling biomolecules (biomolecule tracers), and as reactants, etc.

Metal nanoparticles are used not only as a medium to retain biomolecules, but also to provide versatile labels for the amplification of biosensing events [14, 15], to enhance the amount of immobilized biomolecules in construction of sensors because of the higher surface area, small size, and biocompatibility [16]. Among metal nanoparticles, gold nanoparticles (AuNPs) play a very important role in the development of specific and sensitive assays for clinical diagnosis, bioassay, drug delivery, detection of pathogenic microorganisms in foods and the environment. AuNPs can also provide a biocompatible microenvironment for biomolecules. Use of AuNPs in development of immunosensor, marker diagnosis, and in other medical diagnostics is mainly now in interest. This is because of its biocompatible and highly sensitive nature [9]. AuNPs show a strong absorption band in the visible region due to the collective oscillations of metal conduction band electron in strong resonance with visible frequencies of light (surface Plasmon resonance, SPR). This SPR frequency can be influenced by size and shape of nanoparticles, surface charges, etc. The spherical AuNPs, size 10 nm, have the characteristic UV absorbance at 520 nm and as for gold nanorods, the absorbance will skew towards near infrared range, i.e., 600–900 nm [17]. Deng et al. in 2008 also showed that AuNPs/CNTs multilayer can also provide a suitable microenvironment to retain the enzyme activity and amplify the electrochemical signal of the product of the enzymatic reaction [18]. An immunosensor was reported by immobilizing the human chorionic gonadotropin (hCG) on AuNPs doped three-dimensional (3D) sol-gel matrix [19]. An α-fetoprotein immunosensor was prepared using the AuNPs for the diagnosis of tumor marker expressed in many malignancies as pancreatic, colorectal, gastric, and hepatic carcinomas [20–23]. Further, it has been reported that gold nanorod layers show a better analytical response than AuNPs because they are more sensitive to dielectric constant of the surrounding medium due to the surface plasmon resonance [24].

Among other nanoparticles, Raveendran et al. in 2003 used β-D glucose as the reducing agent and starch as the capping agent to prepare starch silver nanoparticles [25]. Silver nanoparticles preparation was also performed using Heparin [26], Acacia [27], Gum kondgogu [28], and Gum Arabic [29] Pandey et al. in 2012 used the aqueous solution of natural polysaccharide Cyamopsis tetragonaloba as a stabilizing and capping agent for the synthesis of silver nanoparticles [30]. The interaction of nanoparticles with bio-molecules and microorganisms is an expanding field of research. It has been reported that silver nanoparticles undergo a size-dependent interaction with HIV-1, with nanoparticles exclusively in the range of 1–10 nm attached to the virus. It has been suggested that silver nanoparticles interact with the HIV-1 virus via preferential binding to the gp120 glycoprotein knobs. Due to this interaction, silver nanoparticles inhibit the virus from binding to host cells, and this has been demonstrated in vitro [31]. In addition, the strong toxicity that silver exhibits in various chemical forms to a wide range of microorganisms is very well known [32–34], and silver nanoparticles have recently been shown to be a promising antimicrobial material [35].

Diamond particles may also find use in microscale devices for the purpose of sensing and/or drug delivery, which are known as biomedical microelectro-mechanical systems (bioMEMS) [36].

1.7 Use of Nanowires and Nanotubes

Numerous advantages of CNTs as electrode materials have been attested for analysis of diversified chemicals of food quality, clinical, and environmental interest. CNT-based sensors exhibit low limit of detection and fast response due to the signal enhancement and ease of miniaturization provided by high surface area, low overvoltage and rapid electrode kinetics.

Carbon nanotubes consist of concentric cylinders a few nanometers in diameter and up to hundreds of micrometers in length. These cylinders have interlinked hexagonal carbon rings. They were discovered in 1991 by the Japanese scientist, S. Ijima, in soot resulting from an electrical discharge when using graphite electrodes in an argon atmosphere. One of the general ways to produce carbon nanotubes is by means of hydrocarbon pyrolysis in the presence of metal catalyst. This is known as chemical vapor deposition (CVD). These nanotubes may form a bundle of strings of around 0.1 mm in length.

The carbon nanotubes can be divided into two single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). SWCNTs made up of one concentric cylinder and MWCNTs are made up of several concentric cylinders. CNTs are 100 times stronger than steel due to their hexagonal geometry. They have good electronic property due to the presence of free electrons on their surface after the sp2 hybridization of the carbon orbitals.

Figure 1.3 Nanotubes (Reprinted with permission from Elsevier, S. Iijima, Carbon Nanotubes: past, present and future, Physica B, 1–5, (2002) © 2002 Published by Elsevier Science B.V. and from A. Hirsch, Functionalization of Single-Walled Carbon Nanotubes, Angew. Chem. Int. Ed., 2002, 41, 1853, Copyright Wiley-VCH Verlag GmbH & Co. KGaA.)

Nanowires can be defined as structures that have a lateral size constrained to tens of nanometers or less and an unconstrained longitudinal size. At these scales, quantum mechanical effects are important, hence such wires are also known as “quantum wires.”

In the last couple of years, carbon nanotubes have overshadowed nanowires. The use of CNTs for testing with real world samples might be problematic, since several endogenous species in such samples are anticipated to display hydrophobic interactions with CNTs. Electroactive interference is always of great concern due to moderately high anodic potential, leading to the over-estimation of the target analyte level. In spite of the insolubility of CNTs in most common solvents, some progress towards their chemical processing for suspension in solvents has been recently achieved. Moreover, CNTs can be functionalized with different chemical groups using covalent and non-covalent procedures. In order to covalently attach biomolecules, the formation of functional groups on CNTs is required. The carboxylic acid group is widely used because it is easily formed by simple oxidizing treatment. This treatment can also create some other groups as carbonyl, carboxyl, and hydroxyl at the defect sites of the outer graphene sheet. With further treatment with strong acids, all these groups are converted into carboxylic acid [37].

Figure 1.4 Nanowires (Reprinted with permission from http://www.mawi.tu-darmstadt.de).

Figure 1.5 TEM of carbon nanotubes and nanowires.

To preserve the sp2 nanotube structure and thus their important electronic characteristics, non-covalent functionalization is explored, i.e., wrapping with organics [38], polymers [39–42], and wrapping with surfactants [43], etc. Our group has prepared methylene blue-SDS wrapped MWCNTs nanocomposite, which are very effective for the detection of hydrogen peroxide [43]. Here, the sp2 character of MWCNTs was preserved by wrapping with SDS first, followed by the adsorption of methylene blue. The MWCNTs and MB enhances the results synergistically. Moving ahead, our group [44–45] has done the green preparation of anthraquinone derivative-functionalized multi-walled carbon nanotubes nanowires by wrapping MWCNTs with 3-aminopropyltrimethoxysilane followed by linking with anthraquinone-2-carboxylic acid via carbodimide coupling for the detection of dissolved oxygen. In this article, carbodimide coupling is not performed directly onto the wall of MWCNTs, but it was on amino-functionalized MWCNTs.

It is reported in the literature that the detection of ascorbic acid is not possible in the presence of nafion, but the selective electrocatalytic detection of ascorbic acid was successfully possible with Polyaniline/PAA/MWCNTs/nafion nanocrystalline composite material (NCCM), which was prepared by our group [46]. We have also encapsulated the MWCNTs in ormosil along with ferricyanide and HRP enzyme for sensitive and selective detection of hydrogen peroxide [38].

It is well documented that functionalized CNTs can penetrate the plasma membrane. This ability of CNTs has allowed them to possess a large loading capability to carry various bioactive agents, such as drugs [47]. A large surface-to-volume ratio, unique electronic properties, and unique optical and thermodynamic properties make CNTs a welcome component for fabricating highly sensitive biodetectors, which are crucially needed in the diagnosis of viral diseases and the development of new antiviral drugs; chemotherapy; central nervous system disorders; and in tissue engineering, etc. [48–50, 2].

It is reported that pristine SWCNTs exhibit an antimicrobial effect in a size-dependent manner, indicating that they might be useful as building blocks for antimicrobial therapeutics [50–52].

1.8 Use of Porous Silicon

Another nanostructure material that has been studied extensively for nano-sensing applications is nano-crystalline silicon, frequently referred to as porous silicon. Mesoporous materials show ordered arrangements of channels and cavities of different geometries built up from SiO2 units [53]. These materials exhibit variable pore size (2–50 nm), high surface area, high pore volume and homogeneous nanostructures, which can be tailored by synthesis procedure [54]. The pore walls have a high surface density of silanol groups that could be reactive towards appropriate guest molecules [55–56]. Silicious mesoporous materials have the advantage of being biocompatible and degradable in aqueous solution, and thus issues related to the removal of material after use can be avoided. Mesoporous [57–58] silica materials have aroused great interest for biotechnological and biomedical applications because of their large specific surface areas and uniform pores. The location of sensing molecules is on not only the external surface of the materials but also inside the pores, so loading large amounts of sensing molecules or drugs to give fast response. Moreover, it also increases the stability of the enzyme and provides special chemical and physical performance. A nanocomposite of mesoporous silica was prepared for controlled drug delivery [59]. pH-responsive pseudorotaxane-based mesoporous silica nanoparticles were prepared using polyethyleneimine as fixed motif and a or γ-cyclodextrin as movable ring for the delivery of calcein [60]. Novel nanocomposite membranes based on sulfonated mesoporous silica nanoparticles were modified with sulfonated polyimides for direct methanol fuel cells [61].

1.9 Use of Self-Assembled Nanostructures

Several research works have been published on self-assembled nanostructures [62–66]. Ionic self-assembly (ISA) is a non-covalent synthesis strategy that makes use of electrostatic interactions between charged surfactant and oppositely charged oligo-and poly electrolytes. This is somewhat similar to block copolymers and H-bonded amphiphilic polymer systems.

Block copolymer has received considerable attention as a promising platform for the synthesis of nanostructures because of its self-assembling nature to form periodically ordered structure in nanometer scale [67–68]. Oxide, hybrid nanostructure, DNA nanostructures, and self-assembled nanostructures are now in interest for therapeutic applications [5, 10, 69, 70]. Moreover, the self-assembled polymer nanostructures are very interesting for the delivery of anticancer therapeutics. A self-assembled graphene platelet glucose oxidase nanostructure has been reported for glucose bio-sensing [61]. An outstanding review has been reported by Lo et al., in 2010 [71] on various strategies to develop self-assembly of three-dimensional DNA nanostructures for biological applications.

1.10 Receptor-Ligand Nanoarrays

Microarray technology is a very fast growing technology. Nanoarrays are being developed based on interaction between different types of receptors and ligands such as protein and nucleic acids. Several researchers have reported different types of works based on microarrays. Molecular beacons have been applied to pathogen detection [4, 72, 73]. A nanoarray membrane sensor has been prepared for the sensing of water pollutants [74].

Figure 1.6 Different types of self-assembled monolayers

(Reprinted with permission from http://burggarten.ddo.jp).

1.11 Characterization of Nanostructures and Nanomaterials

The structure of nanomaterials determines the properties and performance of the sensor. There are several structural tools to characterize the nanostructures and nanomaterials. The morphology of nanomaterials is characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). SEM is generally used to generate surface topography of nanomaterials [75]. TEM can generate information of chemical composition, crystallographic orientation, electronic structure, and electronic phase shift. Nanocomposites can also be characterized by X-ray diffraction (XRD) and inductively coupled plasma (ICP) [76]. Other techniques may be atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and UV-visible spectra, etc.

The electrochemical behavior of nanomaterials can be characterized by cyclic voltammetry (CV), differential pulse voltammetry (DPV), Chroanocoulometry, etc. The conductivity of the nonmaterial can be characterized by electrochemical impedance (EIS). Thermo gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and energy dispersive X- ray spectra (EDX) have been used to characterize nanocomposites [77–79].

Several characterization techniques and the parameters are shown in Table 1.1.

Table 1.1 Techniques to characterize the properties of nanomaterials.

Techniques

Parameters

Transmission electron microscopy

Size and shape, structure crystalline

High resolution transmission electron microscopy

Size and shape, structure crystalline lattice microanalysis

Atomic force microscopy

Size and shape, size distribution

X-ray diffraction

Crystalline structure

Z potential

Electrical charge

Electrochemical

Concentration, redox potential

1.12 Commercialization Efforts

Medical diagnostics markets represent a unique prospect for the introduction of nanotechnology-based biosensors for commercial applications. Only few have been successfully launched in the market. This is because of some of the characteristics cost, quality control, regulatory requisites, instrumentation design, and test parameter selection are to be taken care of [80]. Remarkable and substantial research efforts are still needed to make commercialization possible. One of the most researched areas in non-enzymatic sensors is the detection of analyte directly at the electrode. This method has several limitations, such as slow reaction kinetics and the need for a large applied potential, which decreases specificity [81]. Nanomaterials have helped beat these limitations and thereby allowed the detection directly at the electrode instead of biological recognition elements.

One of the major challenges limiting commercialization is the device reproducibility, which can be largely controlled by the nanomaterials’ synthesis. Therefore, research on efficient nanomaterials’ synthesis techniques would be of paramount importance for fabrication and introduction of new cost-effective devices to the market.

1.13 Future Perspectives

Using nanomaterials, nano-chemistry and nanotechnology have become integrated disciplines benefiting from the progress in organic, inorganic, polymer, physical, and biochemistry research. It is of utmost importance that the developing markets have already started the use of nanotechnology to develop a range of sensors for clinical purposes. But still more research is needed to develop successful nanomaterials for the fabrication of biosensors. Furthermore, the dimension of the sensors has to be minimized. Improvements in analytical merits of the sensors has been of utmost interest and they have been the principal analytical parameters considered for medical diagnostics.

References

1. Y. Zhang, M. Yang, N.G. Portney, D. Cui, G. Budak, E. Ozbay, M. Ozkan, C.S. Ozkan, Biomed. Microdev. Vol. 10, p. 321, 2008.

2. L. Zhang, T.J. Webster, Nano Today, Vol. 4, p. 66, 2009.

3. S.K. Sahoo, S. Parveen, J.J. Panda, Nanomedicine: Nanotechnology, Biology, and Medicine, Vol. 3, p. 20, 2007.

4. J. Riu, A. Maroto, F.X. Rius, Talanta, Vol. 69, p. 288, 2006.

5. H. Yang, K.L. Metera, H.F. Sleiman, Coordination Chemistry Reviews, Vol. 254, p. 2403, 2010.

6. P. Parhi, C. Mohanty, S.K. Sahoo, Drug Discovery Today, Vol. 17, p. 1044, 2012.

7. A. Tiwari, WILiley-Scrivener Publishing LLC, USA, ISBN 978-1-1182-9032-3, 2013.

8. A. Tiwari, A. Tiwari, Bioengineered Nanomaterials, CRC Press, USA, ISBN 978-1-4665-8595-9, 2013.

9. M. Pumera, S Sanchez, I. Ichinose, J. Tang, Sensors And Actuators, Vol. 123, p. 1195, 2007.

10. A. Tiwari, A. Kumar, Wiley-Scrivener Publishing LLC, USA, ISBN 978-04-709387-99, 2012.

11. S. Chandra, K.C. Barick, D. Bahadur, Advanced Drug Delivery Reviews, Vol. 63, p. 1267, 2011.

12. H.S. Panda, R. Srivastva, D. Bahadur, J. Rhys. Chem. B, Vol. 113, p. 15090, 2009.

13. M.R. Abidian, D.C. Martin, Adv. Func. Mater., Vol. 19, p. 573, 2009.

14. J.M. Pingarron, P.Y. Sedeno, A.G. Cortes, Electrochim. Acta, Vol. 53, p. 5848, 2008.

15. K. Omidfar, F. Khorsand, M.D. Azizi, Biosens. Bioelectron., Vol. 43, p. 336, 2013.

16. X. Luo, A. Morrin, A.J. Killard, M.R. Smyth, Electroanalysis, Vol. 18, p. 319, 2006.

17. L. Tong, Q.S. Wei, A. Wei, X. Cheng, Photochem Photobiol, Vol. 85, p. 21, 2009.

18. L. Deng, Y. Wang, L. Shang, D. Wen, F. Wang, S.A. Dong, Biosens. Bioelectron., Vol. 24, p. 957, 2008.

19. J. Chen, F. Yan, F. Tan, H. Ju, Electroanalysis, Vol. 18, p. 1696, 2006.

20. Y. Zhuo, R. Yuan, Y. Chai, D. Tang, Y. Zhang, N. Wang, W. Li, Q. Zhu, Electrochem. Commun., Vol. 7, p. 355, 2005.

21. D. Dan, X. Xiaoxing, W. Shengfu, Z. Aidong, Talanta, Vol. 71, p. 1257, 2007.

22. X.H. Fu, Electroanalysis, Vol. 19, p. 1831, 2007.

23. X. Li, R. Yuan, Y. Chai, L. Zhang, Y. Zhuo, Y. Zhang, J. Biotechnol., Vol. 123, p. 356, 2006.

24. M. Wasowicz, S. Vishwanathan, A. Dvornyk, K. Grzelak, B. Kludkiewicz, H. Redecka, Biosens. Bioelectron., Vol. 24, p. 284, 2008.

25. P. Raveendran, J. Fu, S.L. Wallen, Journal of the American Chemical Society, Vol. 125, p. 13940, 2003.

26. M.M. Kemp, A. Kumar, S. Mousa, E. Dyskin, M. Yalcin, P. Ajayan, R.J. Linhardt, S.A. Mousa, Nanotechnology Vol., 20, p. 455104, 2009.

27. Y.M. Mohan, K.M. Raju, K. Sambasivudu, S. Singh, B. Sreedhar, B., Journal of Applied Polymer Science, Vol. 106, p. 3375, 2007.

28. A.J. Kora, R.B. Sashidhar, J. Arunachalam, Carbohydrate Polymers, Vol. 82, p. 670, 2010.

29. P.S. Gils, D. Ray, P.K. Sahoo, International Journal of Biological Macromolecules, Vol. 46, p. 237, 2010.

30. S. Pandey, G.K. Goswami, K.K. Nanda, International Journal of Biological Macromolecules, Vol. 51, p. 583, 2012.

31. J.L. Elechiguerra, J.L. Burt, J.R. Morones, A. Camacho-Bragado, X. Gao, H.H. Lara, M.J. Yacaman, Journal of Nanobiotechnology, Vol. 3, p. 6, 2005, doi:10.1186/1477-3155-3-6.

32. S.Y. Liau, D.C. Read, W.J. Pugh, J.R. Furr, A.D. Russell, Lett Appl Microbiol, 25, p. 279, 1997.

33. A. Gupta, S. Silver, Nat. Biotechnol. Vol. 16, p. 888, 1998.

34. K. Nomiya, A. Yoshizawa, K. Tsukagoshi, N.C. Kasuga, S. Hirakawa, J. Watanabe, J. Inorg. Biochem., Vol. 98, p. 46, 2004.

35. I. Sondi, B. Salopek-Sondi, J. Colloid Interface Sci., Vol. 275, p. 177, 2004.

36. R.J. Narayan, R.D. Boehm, A.V. Sumant, Material Today, Vol. 14, p. 154, 2011.

37. X. Qin, H. Wang, X. Wang, Z. Miao, L. Chen, W. Zhao, M. Shan, Q. Chen, Sensors and Actuators B, Vol. 147, p. 593, 2010.

38. I. Tiwari, K.P. Singh, M. Singh, B.C. Upadhyay, V.S. Tripathi, Analytical Letters, Vol. 43, p. 2019, 2010.

39. I. Tiwari, K.P. Singh, M. Singh, Russian Journal of General Chemistry, Vol. 79, p. 2685, 2009.

40. M. Adeli, N. Mirab, M. S. Alavidjeh, Z. Sobhani, F. Atyab, Polymer, Vol. 50, p. 3528, 2009.

41. A.I. Gopalan, K.P. Lee, D. Raghupathy, S.H. Lee, J. W. Lee, Biomaterials, Vol. 30, p. 5999, 2009.

42. I. Tiwari, M. Singh, Polymers for Advanced Nanomaterials: Synthesis, Properties and Applications, Studium Press LLC, Houston, Texas, USA. 2011.

43. I. Tiwari, M. Singh, Microchimica Acta, Vol. 174, p. 223, 2011.

44. I. Tiwari, M. Singh, M. Gupta, Chemistry for Sustainable Development, springerlinkgroups, ICPAC-2010, p. 399.

45. I. Tiwari, M. Singh, M. Gupta, S.K. Aggarawal, Mat, Res. Bulletin, Vol. 47, p. 1697, 2012.

46. I. Tiwari, K.P. Singh, M. Singh, C.E. Bank, Analytical Methods, Vol. 4, p. 118, 2012.

47. J. Safari, Z. Zarnegar, Journal of Saudi Chemical Society, Article in press, 2013.

48. G. Pastorin, Pharm. Res., Vol. 26, p.746, 2009.

49. A. A. Bhirde, ACS Nano, Vol. 3, p. 307, 2009.

50. Y. Zhang, B. Yuhong, B. Yan, Drug Discovery Today, Vol. 15, p. 428, 2010.

51. S. Kang, Langmuir, Vol. 24, p. 6409, 2008.

52. K.A. Mahmoud and J.H.T. Luong, Anal Chem, Vol. 80, p. 7056, 2008.

53. J.Y. Ying, C.P. Mehnert, M.S. Wong, Angew Chem. Int. Ed., Vol. 38, p. 57, 1999.

54. G.J. D.A.A.S. Illia, C. Sanchez, B. Lebeau, J. Patarin, Chem. Rev., Vol. 102, p. 4093, 2002.

55. A. Sousa, K.C. Souza, E.M.B. Sousa, Acta Biomater., Vol. 4, p. 671, 2008.

56. R, Nenkova, D. Ivanova, J. Vladimirova, T. Godjevargova, Sensors and Actuators, Vol. 148, p. 59, 2010.

57. X. Feng, C. Mao, G. Yang, W. Hou, J.J. Zhu, Langmuir, Vol. 22, p. 4384, 2006.

58. T. Shimomura, T. Itoh, T. Sumiya, F. Mizukami, M. Ono, Sens. Actuators B, Vol. 135, p. 268, 2008.

59. S. Al-Kady, M. Gaber, M.M. Hussein, and E.Z.M. Ebeid, European Journal of Pharmaceutics and Biopharmaceutics, Vol. 77, p. 66, 2011.

60. C. Park, K. Oh, S C. Lee, C. Kim, Angew Chem. Int. Ed., Vol. 46, p. 1455, 2007.

61. S. Liu, J. Tiana, L. Wanga, Y. Luoa, W. Lua, X. Suna, Biosensors and Bioelectronics, Vol. 26, p. 4491, 2011.

62. R. Chhabra, J. Sharma, Y. Liu, S. R.H. Yan, Advanced Drug Delivery Reviews, Vol. 62, p. 617, 2010.

63. Y. Zhuo, W. Sun, L. Dong, Y. Chu, Applied Surface Science, Vol. 257, p. 10395, 2011.

64. A. Attia, Z. Y. Ong, J.L. Hedrick, P.P. Lee, P.L. R. Ee, P.T. Hammond, Y.Y. Yang, Current Opinion in Colloid & Interface Science, Vol. 16, p. 182, 2011.

65. T. Zhang, J. Brown, R.J. Oakley, C.F.J. Faul, Current Opinion in Colloid & Interface Science, Vol. 14, p. 62, 2009a.

66. X. Zhang, Q. Guo, D. Cui, Sensors, Vol. 9, p. 1033, 2009b.

67. J.K. Kim, S.Y. Yang, Y. Lee, Y., Y. Kim, Progress in Polymer Science, Vol. 35, p. 1325, 2010.

68. T. Smart, H. Lomas, M. Massignani, M.V.F. Merino, L.R. Perez, G. Battaglia, Nano Today, Vol. 3, p. 38, 2008.

69. N. Wiradharma, Y. Zhang, S. Venktaraman, Y.Y.J.L. Hedrick, Nano Today, Vol. 4, p. 302, 2009.

70. J.H. Lee, Sensors and Actuators B, Vol. 140, pp. 319–336, 2009.

71. P.K. Lo, K.L. Metera, H.F. Sleiman, Current Opinion in Chemical Biology, Vol.14, p. 597, 2010.

72. S. Venkatasubbarao, Trends Biotechnol., Vol. 22, p. 607, 2004.

73. F.H. Sharkey, I.M. Banat, R. Marchant, Appl. Environ. Microbiol, Vol. 70, p. 3795, 2004.

74. Y. Zhuo, R. Yu, R. Yuan, Y. Chai, C. Hong, Journal of Electroanalytical Chemistry, Vol. 628, p. 90, 2009.

75. R, Nenkova, D. Ivanova, J. Vladimirova, T. Godjevargova, Sensors and Actuators, Vol. 148, p. 59, 2010.

76. Q.Q. Xua, C.J. Zhanga, X.Z. Zhanga, J.Z. Yina, Y. Liub, J. of Supercritical Fluids, Vol. 62, p. 184, 2012.

77. J.J. Feng, J.J. Xu, H.Y. Chen, Electrochem. Commun., Vol. 8, p. 77, 2006.

78. P. Paulraj, N. Janaki, S. Sandhya, K. Pandian, Colloids and Surfaces A: Physicochem. Eng. Aspects, Vol. 377, p. 28, 2011.

79. Y. Gao, D. Shan, F. Cao, J. Gong, X. Li, H.Y. Ma, Z.M. Su, L.Y. Qu, J. Phys. Chem. C, Vol. 113, p. 15175, 2009.

80. W.G. Lee, Y.G. Kim, B.G. Chung, U. Demirci, A. Khademhosseini, Adv. Drug Del. Rev., Vol. 62, p. 449, 2010.

81. M. Shamsipur, Bioelectrochemistry, Vol. 77, p. 120, 2010.

Chapter 2

Construction of Nanostructures: A Basic Concept Synthesis and Their Applications

Rizwan Wahab1,*, Farheen Khan2, Nagendra K. Kaushik3, Javed Musarrat4 and Abdulaziz A.Al-Khedhairy1

1College of Science, Department of Zoology,, King Saud University, Riyadh, Saudi Arabia

2Department of Chemistry, Aligarh Muslim University, Uttar Pradesh, India

3Plasma Bioscience Research Center, Kwangwoon University, Seoul, South Korea

4Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim University, India.

*Corresponding author: [email protected]

Abstract

Nanotechnology is a branch of materials science, which connects several branches of basic sciences and manipulates nanometer-length atoms, molecules, and big molecular structures. The technology includes a fundamental understanding of physical and chemical properties. It also includes the phenomena of nanostructures and nanomaterials. In this chapter, initial synthesis of nanostructures such as quantum dots, nanoparticles, nanorods, nanospheres, nanoflowers, nanobelts, nano and micro-sheets, micro-flowers, micro-spheres, etc., using various precursors and techniques such as solution/precipitation, vapor phase growth, chemical vapor deposition, plasma enhanced CVD (PE-CVD), sol-gel, sonochemical hydrothermal, etc., have been described. A general introduction with literature review of the constructed nanostructure materials and general definitions are also presented in detail. The morphological, elemental, and optical characterizations such as XRD, FE-SEM, TEM, UV-Vis, Photoluminescence (PL), Raman-Scattering, and for the compositional and surface bonded states of nanostructures were evaluated through FTIR and X-Ray Photoelectron Spectroscopy (XPS) etc., and techniques used are also explained. Finally, the future directions for the study of nanostructures and its possible applications are also highlighted.

Keywords: Construction, nanostructures, synthetic methods, chemical methods, physical methods, zinc oxide, quantum dots, growth mechanism

2.1 Introduction

Nanotechnology is the science that exploits the materials at nanometer scale level. In other words, “Nano” means 10−9, where 1 nanometer is equivalent to one billionth of a meter. This technology allows the production and manipulation of minute objects that measure as little as one billionth of a meter (the nanometer). Due to the nanoscale size, the technology exhibits innovative and significantly improved physical chemical and biological properties. The term nanotechnology includes a variety of different fields of basic sciences, such as engineering, chemistry, physics, biology, electronics, and medicine, among others, but all are concerned with bringing existing technologies down to a very small scale, measured in nanometers. The technology includes the study of physical and chemical properties of nanostructures. Nanostructures are made up of a limited number of atoms, which have specific shapes and have at least one of their dimensions ranging over order of a few nanometers such as nanodots, nanoparticles, nanotubes, nanowires, nanorods, and nanoribbons, nanofibers, nanopores, etc. [1–5]. In order to understand the properties of nanostructures and their applications, synthesis/fabrication is the first step in the nanotechnology [1–5].

2.1.1 Importance of Nanomaterials

Nanomaterials at the nanoscale level are highly attractive and have great potential benefits for the physical and biological aspects. As we know, nanoscale materials have various shapes and structures such as spheres, needles, tubes, plates with amorphous pore-sizes in nanometer range. The nanomaterial characteristics’ properties are potentially significant for the size, shape, agglomeration, surface area, surface chemistry, surface charge (providing supports for cell in more number), and porosity (isothermal gas-adsorption) [5]. The dimension plays a significant role to explore the properties the materials; on the basis of their structures, nanomaterials are typically zero (quantum dots (1–10 nm)/nanoparticles (1–100 range)), one (nanorods (1–100 nm)/nanowires (1–100nm)/nanotubes (1–100nm)) and two-dimensional (nanofilms (micron size)).

2.1.2 Synthetic Methods

2.1.2.1 Solution/Chemical Methods

The synthesis and characterization of nanostructures materials attracted great interest due to their novel properties and application in various optoelectronic, chemical and biological process. Various types of fabrication techniques have been explored in the literature for the synthesis of nanostructures. Typically, there are two principal ways to fabricate metal oxide nanostructures, such as (1) physical methods (2) solution/synthesis/chemical-based methods.

2.1.2.2 Physical Methods

Various methods have been adopted to prepare nanostructures via physical methods, such as vapor phase growth, chemical vapor deposition, metal-organic CVD, plasma enhanced CVD (PECVD), rapid thermal CVD, atmospheric pressure CVD, low pressure CVD, ultra-high vacuum CVD, atomic layer CVD, vapor-solid mechanism, vapor-liquid-solid mechanism, etc.

2.1.2.2.1 Vapor Phase Method

Vapor phase growth process is based on the reaction between metal vapor source and gases such as oxygen, nitrogen, etc. Several techniques can be applied, including thermal chemical vapor deposition (CVD), thermal evaporation, pulsed laser deposition (PLD), and metal-organic chemical vapor deposition (MOCVD) exploited to control the diameter, aspect ratio, and crystallinity of the material [6].

2.1.2.2.2 Chemical Vapor Deposition (CVD)

The chemical vapor deposition (CVD) technique is a chemical process from which thin films of various materials can be deposited. CVD is widely used in the semiconductor industry, as part of the semiconductor device fabrication process, to deposit various films including: polycrystalline, amorphous, and epitaxial silicon, SiO2, silicon germanium, Tungsten, silicon nitride, silicon oxynitride, titanium nitride, and various high-k dielectrics. A number of forms of CVD are in wide use and are frequently referenced in the literature. Some of these forms are MOCVD-CVD processes, which are based on metal-organic precursors, such as Tantalum Ethoxide, Ta(OC2H5)5, to create Ta2O5, Tetra Dimethyl amino Titanium (or TDMAT) to create TiN.

2.1.2.2.3 Plasma Enhanced Chemical Vapor Deposition (PECVD)

Plasma enhanced chemical vapor deposition (PECVD) is an excellent alternative for depositing a variety of thin films at lower temperatures than those utilized in CVD reactors without settling for a lesser film quality. For example, high-quality silicon dioxide films can be deposited at 300 to 350°C while CVD requires temperatures in the range of 650 to 850°C to produce similar quality films. PECVD uses electrical energy to generate a glow discharge (plasma) in which the energy is transferred into a gas mixture. This transforms the gas mixture into reactive radicals, ions, neutral atoms and molecules, and other highly excited species. These atomic and molecular fragments interact with a substrate and depending on the nature of these interactions, either etching or deposition process occurs at the substrate. Since the formation of the reactive and energetic species in the gas phase occurs by collision in the gas phase, the substrate can be maintained at a low temperature. Hence, film formation can occur on substrates at a lower temperature than is possible in the conventional CVD process, which is a major advantage of PECVD [7–8].

2.1.2.2.4 Atomic Layer CVD

Atomic layer chemical vapor deposition (ALCVD) is a process by which two complementary precursors (e.g., Al(CH3)3 and H2O) are alternatively introduced into the reaction chamber. Typically, one of the precursors will adsorb onto the substrate surface, but cannot completely decompose without the second precursor. The precursor adsorbs until it saturates the surface and further growth cannot occur until the second precursor is introduced. Thus the film thickness is controlled by the number of precursor cycles rather than the deposition time as is the case for conventional CVD processes. In theory ALCVD allows for extremely precise control of film thickness and uniformity [7–8].

2.1.2.3 Chemical-Based Synthesis

Chemical synthesis is generally known as a cheap and inexpensive process, which gives nanostructures in bulk amounts. There are various methods for chemical synthesis, such as the sol-gel method, template-assisted synthesis, soft chemical method, aqueous and non-aqueous solution process, electrochemical deposition, surfactant-assisted process, sonochemical synthesis, hydrothermal synthesis, solvothermal and ionothermal synthesis, etc.

The fabrications of nanostructures have been adopted from the above processes. The chemical technique, or solution method, provides an easy and convenient method, and it is an effective process for the large-scale production of nanocrystals. Here, we focused on synthesis of various types of metal oxides nanostructures. The present section covers in three major parts: synthesis of various types of nanostructures, characterization, and their possible applications. It is notable to mention that during the experiments, controlling various reaction parameters will control the growth kinetics and chemical reaction kinetics. The chemical thermodynamics and physical characteristics of materials will also be involved in designing the desired nanomaterials synthesis. The synthesis and characterization of metal oxide nanostructure is studied with different configurations.

2.1.2.4 Properties of Zinc Oxide Nanostructures and Their Construction

The white crystalline solid ZnO is nearly insoluble in water but soluble in acids or alkalis. The crystalline zinc oxide exhibits the piezoelectric effect, luminescent (it changes color from white to yellow when heated, and back again when cooled down), and light-sensitive properties. Pure crystalline zinc oxide decomposes into zinc vapor and oxygen at around 1975°C.

Zinc oxide exhibits three phases, i.e., wurtzite, sphalerite (zinc blende), and metastable, but the wurtzite zinc oxide structure is a natural form of ZnO. The molecular structure of wurtzite zinc oxide is hexagonal close packed (hcp) and the crystal lattice of unit cell is a=0.3249, c=0.52049 nm and belonging to space group of P63 mc. Figure 2.1 is the crystal structure of wurtzite structured ZnO, which shows the crystal geometry of the zinc oxide. ZnO is a polar crystal, where zinc and oxygen atoms are arranged alternatively along the c-axis direction. The top surface is Zn-terminated (0001) while the bottom surface is oxygen-terminated (000). The Zn-(0001) is catalytically active while the O-(000) is inert [9]. Therefore the top surface would be energetically active. The growth of zinc oxide nanostructures is dependent on its growth velocities of different growth planes in the ZnO crystals. According to Laudise et al., [10], the higher the growth rate, the quicker the disappearance of plane, which leads to the pointed ends of the c-axis. The growth velocities of the ZnO crystals in different directions are [0001] > [01 ] > [010] > [011] > [000], under hydrothermal conditions. Therefore, the (0001) plane, the most rapid growth rate plane, disappears, which leads to the pointed shape in an end of the (0001) plane. Moreover, the (000) plane has the slowest growth rate which leads to the plain shape in another end. In our synthesized nanostructures, the observed nanorods have pointed tips with the flat down surfaces, which is consistent with the growth habit of ZnO crystals. It should be noted that uncertainty still exists in some of these values. For example, there have been few reports of p-type ZnO, and therefore the whole mobility and effective mass are still in debate [9–10].

Figure 2.1 Crystal structures of hexagonal model of ZnO.

ZnO is attractive to the scientific community because it has vast applications in various fields, such as UV light emitters, varistors, transparent high power electronics, surface acoustic wave devices, piezoelectric transducers, solar cells, chemical sensors, gas sensors and biosensors. With a direct and wide band gap 3.37eV and larger exciton binding energy of 60meV at room temperature, ZnO holds excellent promise for the blue and ultraviolet optical devices.

2.2 Formation of Zinc Oxide Quantum Dots (ZnO-QDs) and Their Applications

Reports related to the formation of zinc oxide quantum dots (ZnO-QDs) and their possible applications have been published recently by several researchers, such as Chen et al., who presented the synthesis of zinc oxide quantum dots via a facile electrochemical etching method. The electrochemically prepared ZnO-QDs exhibit uniform particles with an average diameter of 5.0 nm and possess good electrochemiluminescent activities [11].

In another report published by Sato et al., [12] polymer (Poly(methyl methacrylate) (PMMA)/zinc oxide (ZnO)) coated zinc oxide nanocomposite was fabricated, which composed with high molecular weight PMMA or PCEM. The particles were successfully prepared by atom transfer radical polymerization (ATRP) initiated by 2-bromo-2-methylpropionyl (BMP) group (ZnBM) introduced onto the ZnO nanoparticle surfaces.

The zinc (ZnO) quantum dots (QDs) have been used as light-emitting constructed by employing the QDs as active layers. The near-band-edge emissions have been observed from the diodes shows a significant blue-shift, which is verified to come from the size effect of the QDs due to their small size [13].

Omata et al. [14] presented a novel synthesis method to fabricate the organic molecule capped colloidal zinc oxide quantum dots. The diameters of each ZnO-QD are in the range of 3–7 nm, which are highly dispersible in various organic solvents. These QDs exhibit quantum size effect upon UV emission and it was controlled between 3.39 and 3.54 eV. The prepared QDs shows the intensity of photoluminescence UV emission is 1.5 times higher than that of the visible emission [14].

The zinc oxide quantum dots (ZnO-QDs) diameters from 17 to ~ 30 nm and heights from 2 to ~ 4 nm have been successfully deposited by reactive ion beam sputter deposition. The nano-scale ripples are used as excellent Si (100) templates for the deposition of semi conductor nanostructures. They have prepared quasi periodical nano-scale ripples on Si (100) substrates with spatial wavelength λ from ~ 70 to ~ 150 nm by ion beam sputtering. On substrates with λ ~ 150 nm, ZnO-QDs were distributed evenly across the wafer, while on substrates with λ ~ 70nm, ZnO-QDs were preferentially located along the crest of the nano-scale ripples [15].

In another report, carbon coated zinc oxide quantum dots (CQDs) of hetrostructure have been prepared by Li et al. [16], via a sol-gel method with a spin-coating processing. The obtained CQDs were characterized with well-known techniques such as TEM, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, photoluminescence (PL) emission spectroscopy and photocurrent–voltage curves. Additionally, the photo catalytic property of the prepared heterostructure has also been investigated by using Rhodamine B as a test substance. The obtained results investigates that some electronic interaction has been developed between quantum dots of zinc oxide and carbon coated zinc oxide QDs. The interaction contributes the improvement of charge separation and recombination, which enhances the photo catalytic property of the material [6].

Ghaemi et al. [17] describes the formation of transparent Al2O3–SiO2–ZnO–R2O glass ceramics fabricated by mealting method. The obtained results showed that the transparent glass ceramic including ZnO quantum dots was obtained after heat treatment from 700 °C to 800°C for the sample containing K2O. The glasses containing Li2O and Na2O were opal after heat treatment. The PL studies showed that the samples containing K2O exhibit longer wavelength, when the heat treatment temperature and time increased, which is due to the enhancement of size of ZnO quantum dots [17].

A very small size of zinc oxide quantum dots (2.5–4.5 nm) were prepared via wet chemical method based on alkaline-activated hydrolysis with condensation of zinc acetate solutions. The gas sensing device has been tested with the use of drop casted film of zinc oxide quantum dots. The promising results have been obtained with the test of NO2, acetone and methanol. The ZnO quantum dots showed good sensitivity at 200°C at low concentration (2 ppm), while at temperature above 350°C, high responses are obtained for acetone and methanol [18].

Wahab et al. [19] prepared the ZnO-QDs with the use of chemicals zinc nitrate hexa hydrate (Zn(NO3)2.2H2O), n-propylamine and SDS surfactant in 6 h refluxing. The crystalline property of the obtained nanostructure as analyzed with X-ray diffraction (XRD), which reveals that prepared QDs size is very small and exhibits wurzite phase. The general morphology of synthesized QDs were observed with using FE-SEM and TEM, which showed that the average size are in the range of ~6–7nm. The elemental and compositional analysis was also carried out with FTIR spectroscopy. The prepared ZnO-Quantum dots have been applied for the comparison study of photocatalytic oxidation properties with commercial TiO2 in gaseous phase and was designed and performed to degrade acetaldehyde (CH3CHO). The obtained results showed that the 1st order rate constant for the prepared QDs of ZnO (1.9×10−2/min) is one magnitude higher than that of Degussa P-25 (8.3 × 10−3/min). The efficiencies were found to be 70% and 92% for Degussa P-25 and ZnO-QDs respectively in 120 min of reaction time.

The morphology and size of the prepared ZnO-QDs was carried out by using field emission electron microscopy (FE-SEM). Figure 2.2(a & b) shows the low and high magnified images of grown ZnO-QDs. From the images, it is observed that the grown NPs are in spherical shape with an aggregated form. The size of each quantum dots (QD) of zinc oxide seen is very small, which is about ~6–7nm. The morphological observation was further carried out by using transmission electron microscopy (TEM) equipped with the selected area electron diffraction (SAED) pattern setup. Figure 2.2(c) show the low magnified image TEM observation is consistent with the FESEM observation (figure 2.2(a & b)) and it shows that the QDs are ~6–7nm in size and are nearly spherical in shape. The high resolution TEM (HR-TEM) image of these QDs shows the lattice fringes between two adjacent planes are about 0.265nm apart, which is equal to the lattice constant of wurtzite ZnO, again confirming the wurtzite hexagonal phase. The corresponding SAED pattern (figure 2.2(d) inset) is consistent with the HR-TEM observation (figure 2.2(d)) and corresponds that the synthesized product is crystalline in nature.

Figure 2.2 FESEM images of ZnO-QDs: (a–b) low magnification and (c) high magnification whereas (c) shows the low magnification TEM image of the ZnO-QDs at 0.3M concentration of zinc acetate di-hydrate, n-propyamine and SDS and (b) HR-TEM image shows the difference between two lattice fringes, which is ~0.265 nm.

[Reprinted with permission from Ref. 19, R. Wahab et al., Chem. Engg. J., 226, 154, 2013; Copyright @ Elsevier (2013)].

The crystallinity of the prepared QDs was observed via X-ray diffraction pattern (figure 2.3