Biosensors: Fundamentals and Applications Bansi Dhar Malhotra and Chandra Mouli Pandey A Smithers Group Company Shawbury, Shrewsbury, Shropshire, SY4 4NR, United Kingdom Telephone: +44 (0)1939 250383 Fax: +44 (0)1939 251118 http://www.polymer-books.com First Published in 2017 by Smithers Rapra Technology Ltd Shawbury, Shrewsbury, Shropshire, SY4 4NR, UK © Smithers Information Ltd., 2017 All rights reserved. Except as permitted under current legislation no part of this publication may be photocopied, reproduced or distributed in any form or by any means or stored in a database or retrieval system, without the prior permission from the copyright holder. A catalogue record for this book is available from the British Library. Every effort has been made to contact copyright holders of any material reproduced within the text and the authors and publishers apologise if any have been overlooked. ISBN: 978-1-91024-278-0 (hardback) 978-1-91024-279-7 (ebook) Typeset by Integra Software Services Pvt. Ltd. Preface Biosensors have emerged recently as a vibrant technique for qualitative and quantitative determination of various analytes for environmental, clinical, agricultural, food, and defence applications. Many biosensors have shown excellent characteristics for synthetic samples and pristine laboratory specimens. However, these interesting devices are not yet sufficiently robust for real-world application. The existing limitations are related directly to the operational and long- term stability of the biological receptor and physical transducer. Some of the other limitations could be attributed to poor reproducibility between sensors and selectivity in complex matrices. For practical applications, the most important obstacles are encountered once the sensor is used outside laboratory conditions and is applied for in situ monitoring of real samples. The areas of development that are expected to have an impact on biosensor technology are immobilisation techniques, nanotechnology, miniaturisation, and multi-sensor array determinations. In this book, the basic concepts of biosensors are presented pertaining to fabrication and their wide range of applications in different fields. In Chapter 1, the fundamentals of biosensors are discussed. Although many new types of transducers are being developed continuously for use in biosensors, optical (i.e., luminescence, absorption, and surface plasmon resonance), electrochemical and mass (i.e., surface acoustic wave, and microbalance) transduction methods are discussed in detail because these are traditional methods. The core part of biosensing lies in molecular recognition. In Chapter 2, efforts are made to describe different biological recognition elements that can be used for the development of biosensors and their interactions for the detection of analytes. In the development of a whole range of biosensors, the iii Biosensors: Fundamentals and Applications immobilisation of bioreceptors has a key role because it ensures the high reactivity, orientation, accessibility and stability of the surface- confined probe and avoids non-specific binding. Many methods, such as absorption, electrochemical entrapment, biotin–avidin coupling, and covalent binding, can be used for biomolecule immobilisation, and selection of these methods is reliant on the choice of the matrix. In Chapters 3 and 4, the applications of various conducting polymers and nanomaterials are summarised. Biosensors based on highly sensitive and precise nanomaterials have opened up the possibility of creating novel technologies for rapid, early-stage detection and the diagnosis of diseases. Different characteristic properties of nanomaterials have paved the way for the fabrication of a huge range of biosensors with improved analytical capacities. Chapter 5 describes the broad range of application of biosensors for the detection of various analytes. Special efforts have been made on the application of biosensors for the detection of cancer biomarkers. In Chapter 6, we explore the potential of biosensors for the design and development of ‘smart’ sensing technologies using novel sensing strategies, such as ‘lab-on-a-chip’, paper-based sensors, and wearable sensors. We hope that this book will cater to the urgent requirement of students and senior researchers venturing into this field of interdisciplinary research that has enormous practical applications. We thank Professor Yogesh Singh (Vice Chancellor, Delhi Technological University, Delhi, India) for his interest in this work. C.M. Pandey acknowledges the financial support received from the Department of Science and Technology, India, under the DST-INSPIRE Faculty project (Grant No. DST/INSPIRE/04/2015/000932). iv Contents Preface......................................................................................... iii 1 Fundamentals of Biosensors.................................................. 1 1.1 Introduction.................................................................. 1 1.2 Developments in Biosensors.......................................... 3 1.2.1 Electrochemical Biosensors................................ 4 1.2.1.1 Amperometric Sensors........................ 7 1.2.1.1.1 Cyclic Voltammetry ���������� 8 1.2.1.2 Potentiometric Sensor......................... 9 1.2.1.3 Conductometric Sensors.................... 10 1.2.1.4 Electrochemical Impedance Spectroscopy. ����������������������������������� 11 1.2.2 Optical-based Biosensor.................................. 14 1.2.2.1 Surface Plasmon Resonance.............. 15 1.2.2.2 Chemiluminescence........................... 17 1.2.2.3 Fibre Optic Biosensor........................ 18 1.2.3 Piezoelectric Sensors........................................ 19 1.2.4 Calorimetric-based Biosensor.......................... 21 1.3 Conclusions................................................................ 21 References........................................................................... 22 2 Biorecognition Elements in a Biosensor............................... 27 2.1 Introduction................................................................ 27 2.2 Immobilisation Methods............................................. 28 v Biosensors: Fundamentals and Applications 2.2.1 Adsorption...................................................... 28 2.2.2 Covalent Bonding............................................ 28 2.2.3 Crosslinking.................................................... 29 2.2.4 Entrapment..................................................... 30 2.3 Principles of Biorecognition........................................ 30 2.3.1 Natural Biorecognition Elements..................... 31 2.3.1.1 Enzymes............................................ 31 2.3.1.2 Antibodies........................................ 35 2.3.2 Semi-synthetic Biorecognition Element............ 38 2.3.2.1 Nucleic Acids.................................... 38 2.3.2.2 Aptamers.......................................... 41 2.3.3 Synthetic Recognition Elements....................... 43 2.3.3.1 Imprinted Polymers........................... 43 2.4 Conclusions................................................................ 46 References........................................................................... 47 3 Nanomaterial-based Biosensors........................................... 55 3.1 Introduction................................................................ 55 3.2 Metal Nanoparticle-based Biosensors......................... 57 3.3 Nanostructured Metal Oxide-based Biosensors.......... 62 3.4 Carbon Nanotube-based Biosensors........................... 67 3.5 Graphene-based Biosensors......................................... 71 3.6 Quantum Dot-based Biosensors.................................. 76 3.7 Conclusions................................................................ 80 References........................................................................... 81 4 Conducting Polymer-based Biosensors................................. 97 4.1 Introduction................................................................ 97 4.2 Application of Polyaniline in Biosensors................... 102 4.3 Conducting Polypyrrole-based Biosensors................. 112 vi Contents 4.4 Polythiophenes-based Biosensors.............................. 118 4.5 Conclusions.............................................................. 122 References......................................................................... 122 5 Applications of Biosensors................................................. 133 5.1 Introduction.............................................................. 133 5.2 Biosensors for Food/Water Safety............................. 135 5.2.1 Biosensors for Detection of Foodborne/Waterborne Pathogens................ 136 5.2.1.1 Biosensors for Escherichia Coli Detection ������������������������������� 136 5.2.1.2 Biosensors for Salmonella Detection ��������������������������������������� 144 5.2.2 Biosensors for Mycotoxin Detection............. 145 5.2.2.1 Biosensors for Aflatoxin Detection ��������������������������������������� 145 5.2.2.2 Biosensors for Ochratoxin Detection ��������������������������������������� 148 5.3 Biosensors for the Defence Industries........................ 152 5.4 Biosensors for Clinical Diagnostics........................... 154 5.4.1 Biosensors for Glucose Detection.................. 155 5.4.2 Biosensors for Cholesterol Detection............. 157 5.4.3 Biosensors for Cancer Detection.................... 161 5.5 Biosensors for Environmental Monitoring...............