Table of Contents

Preface xix Acknowledgements xxi List of Symbols xxiii List of Acronyms xxxi 1 What are Chemical Sensors? 1 1.1 Chemical Sensors: Definition and Components 1 1.2 Recognition Methods 2 1.2.1 General Aspects 2 1.2.2 Ion Recognition 3 1.2.3 Recognition by Affinity Interactions 3 1.2.4 Recognition by Nucleic Acids 3 1.2.5 Recognition by Enzymes 4 1.2.6 Recognition by Cells and Tissues of Biological Origin 4 1.2.7 Gas and Vapor Sorption 4 1.3 Transduction Methods 4 1.3.1 General Aspects 4 1.3.2 Thermometric Transduction 5 1.3.3 Transduction Based on Mechanical Effects 5 1.3.4 Resistive and Capacitive Transduction 5 1.3.5 Electrochemical Transduction 5 1.3.6 Optical Transduction 6 1.4 Sensor Configuration and Fabrication 6 1.5 Sensor Calibration 7 1.6 Sensor Figures of Merit 8 1.6.1 Reliability of the Measurement 9 1.6.2 Selectivity and Specificity 10 1.6.3 Detection and Quantification Capabilities 10 1.6.4 Response Time 11 1.7 Sensor Arrays 11 1.7.1 Quantitative Analysis by Cross-Sensitive Sensor Arrays 11 1.7.2 Qualitative Analysis by Cross-Sensitive Sensor Arrays 12 1.7.3 Artificial Neural Network Applications in the Artificial Nose/Tongue 13 1.7.4 Outlook 14 1.8 Sensors in Flow Analysis Systems 14 1.9 Applications of Chemical Sensors 14 1.9.1 Environmental Applications of Chemical Sensors 15 1.9.2 Healthcare Applications of Chemical Sensors 15 1.9.3 Application of Chemical Sensors in the Food Industry, Agriculture and Biotechnology 16 1.9.4 Chemical Sensors in Defense Applications 16 1.10 Literature on Chemical Sensors and Biosensors 17 1.11 Organization of the Text 17 References 19 2 Protein Structure and Properties 21 2.1 Amino Acids 21 2.2 Chemical Structure of Proteins 21 2.3 Conformation of Protein Macromolecules 22 2.4 Noncovalent Chemical Bonds in Protein Molecules 24 2.5 Recognition Processes Involving Proteins 25 2.6 Outlook 26 References 27 3 Enzymes and Enzymatic Sensors 28 3.1 General 28 3.2 Enzyme Nomenclature and Classification 28 3.3 Enzyme Components and Cofactors 30 3.4 Some Enzymes with Relevance to Biosensors 32 3.4.1 Oxidases 32 3.4.2 Dehydrogenases 33 3.4.3 Hydrolases 34 3.4.4 Lyases 35 3.4.5 Outlook 35 3.5 Transduction Methods in Enzymatic Biosensors 36 3.5.1 Transduction Methods 36 3.5.2 Multienzyme Sensors 37 3.6 Kinetics of Enzyme Reactions 38 3.6.1 The Michaelis-Menten Mechanism 38 3.6.2 Other Mechanisms 40 3.6.3 Expressing the Enzyme Activity 41 3.6.4 pH Effect on Enzyme Reactions 42 3.6.5 Temperature Effect on Enzyme Reactions 43 3.6.6 Outlook 43 3.7 Enzyme Inhibition 44 3.7.1 Reversible Inhibition 44 3.7.2 Irreversible Inhibition 46 3.7.3 Enzymatic Sensors for Inhibitors: Design and Operation 46 3.7.4 Applications of Enzyme-Inhibition Sensors 47 3.8 Concluding Remarks 48 References 49 4 Mathematical Modeling of Enzymatic Sensors 50 4.1 Introduction 50 4.2 The Enzymatic Sensor Under External Diffusion Conditions 50 4.2.1 The Physical Model 50 4.2.2 The Mathematical Model 51 4.2.3 The Zero-Order Kinetics Case 52 4.2.4 The First-Order Kinetics Case 52 4.2.5 The Dynamic Range and the Limit of Detection Under External Diffusion Conditions 54 4.3 The Enzymatic Sensor Under Internal Diffusion Control 55 4.3.1 The Steady-State Response 55 4.3.2 The Transient Regime and the Response Time Under Internal Diffusion Conditions 58 4.4 The General Case 60 4.4.1 The Model 60 4.4.2 Effect of the Biot Number 61 4.4.3 Effect of Partition Constants and Diffusion Coefficients 63 4.4.4 Experimental Tests for the Kinetic Regime of an Enzymatic Sensor 63 4.5 Outlook 64 References 64 5 Materials and Methods in Chemical-Sensor Manufacturing 66 5.1 Introduction 66 5.2 Noncovalent Immobilization at Solid Surfaces 66 5.3 Covalent Conjugation 67 5.3.1 Zero-Length Crosslinkers 68 5.3.2 Bifunctional Crosslinkers 69 5.3.3 Immobilization by Protein Crosslinking 69 5.4 Supports and Support Modification 70 5.4.1 General Aspects 70 5.4.2 Natural Polymers 71 5.4.3 Synthetic Polymers 72 5.4.4 Coupling to Active Polymers 72 5.4.5 Coupling to Inactive Polymers 72 5.4.6 Inorganic Supports 73 5.4.7 Carbon Material Supports 74 5.4.8 Metal Supports 75 5.4.9 Semiconductor Supports 76 5.5 Affinity Reactions 77 5.6 Thin Molecular Layers 78 5.6.1 Self-Assembly of Amphiphilic Compounds 78 5.6.2 Bilayer Lipid Membranes 79 5.6.3 Alternate Layer-by-Layer Assembly 80 5.7 Sol-Gel Chemistry Methods 81 5.8 Hydrogels 83 5.8.1 Physically Crosslinked Hydrogels 84 5.8.2 Chemically Crosslinked Hydrogels 84 5.8.3 Redox Hydrogels 84 5.8.4 Responsive Hydrogels 84 5.9 Conducting Polymers 86 5.10 Encapsulation 88 5.11 Entrapment in Mesoporous Materials 89 5.12 Polymer Membranes 90 5.12.1 Deposition of Polymers onto Solid Surfaces 90 5.12.2 Perm-Selective Membranes 91 5.13 Microfabrication Methods in Chemical-Sensor Technology 92 5.13.1 Spot Arraying 92 5.13.2 Thick-Film Technology 92 5.13.3 Thin-Film Techniques 94 5.13.4 Soft Lithography 95 5.13.5 Microcontact Printing of Biocompounds 95 5.14 Concluding Remarks 97 References 97 6 Affinity-Based Recognition 101 6.1 General Principles 101 6.2 Immunosensors 101 6.2.1 Antibodies: Structure and Function 101 6.2.2 Antibody-Antigen Affinity and Avidity 103 6.2.3 Analytical Applications 103 6.2.4 Label-Free Transduction Methods in Immunosensors 104 6.2.5 Label-Based Transduction Methods in Immunosensors 104 6.2.6 Enzyme Labels in Immunoassay 105 6.3 Immobilization Methods in Immunosensors 106 6.4 Immunoassay Formats 106 6.5 Protein and Peptide Microarrays 109 6.6 Biological Receptors 110 6.7 Artificial Receptors 111 6.7.1 Cyclodextrins and Host-Guest Chemistry 111 6.7.2 Calixarenes 113 6.7.3 Molecularly Imprinted Polymers (MIPs) 113 6.8 Outlook 115 References 115 7 Nucleic Acids in Chemical Sensors 118 7.1 Nucleic Acid Structure and Properties 118 7.2 Nucleic Acid Analogs 121 7.3 Nucleic Acids as Receptors in Recognition Processes 122 7.3.1 Hybridization: Polynucleotide Recognition 122 7.3.2 Recognition of Non-Nucleotide Compounds 123 7.3.3 Recognition by Aptamers 124 7.4 Immobilization of Nucleic Acids 126 7.4.1 Adsorption 126 7.4.2 Immobilization by Self-Assembly 127 7.4.3 Immobilization by Polymerization 127 7.4.4 Covalent Immobilization on Functionalized Surfaces 128 7.4.5 Coupling by Affinity Reactions 128 7.4.6 Polynucleotides-Nanoparticles Hybrids 129 7.5 Transduction Methods in Nucleic Acids Sensors 129 7.5.1 Label-Free Transduction Methods 129 7.5.2 Label-Based Transduction 129 7.5.3 DNA Amplification 130 7.6 DNA Microarrays 131 7.7 Outlook 132 References 133 8 Nanomaterial Applications in Chemical Sensors 135 8.1 Generals 135 8.2 Metallic Nanomaterials 136 8.2.1 Synthesis of Metal Nanoparticles 136 8.2.2 Functionalization of Gold Nanoparticles 137 8.2.3 Applications of Metal Nanoparticles in Chemical Sensors 138 8.3 Carbon Nanomaterials 138 8.3.1 Structure of CNTs 139 8.3.2 Synthesis of CNTs 140 8.3.3 Chemical Reactivity and Functionalization 140 8.3.4 CNTApplications in Chemical Sensors 142 8.3.5 Carbon Nanofibers (CNFs) 142 8.4 Polymer and Inorganic Nanofibers 144 8.5 Magnetic Micro- and Nanoparticles 145 8.5.1 Magnetism and Magnetic Materials 145 8.5.2 Magnetic Nanoparticles 146 8.5.3 Magnetic Biosensors and Biochips 146 8.5.4 Magnetic Nanoparticles as Auxiliary Components in Biosensors 148 8.5.5 Outlook 148 8.6 Semiconductor Nanomaterials 149 8.6.1 Synthesis and Functionalization of Quantum Dots 149 8.6.2 Applications of Quantum Dots 151 8.7 Silica Nanoparticles 151 8.7.1 Synthesis, Properties, and Applications 151 8.8 Dendrimers 152 8.8.1 Properties and Applications 152 8.9 Summary 153 References 153 9 Thermochemical Sensors 157 9.1 Temperature Transducers 157 9.1.1 Resistive Temperature Transducers 157 9.1.2 Thermopiles 157 9.2 Enzymatic Thermal Sensors 158 9.2.1 Principles of Thermal Transduction in Enzymatic Sensors 158 9.2.2 Thermistor-Based Enzymatic Sensors 159 9.2.3 Thermopile-Based Enzymatic Sensors 160 9.2.4 Multienzyme Thermal Sensors 160 9.2.5 Outlook 161 9.3 Thermocatalytic Sensors for Combustible Gases 162 9.3.1 Structure and Functioning Principles 162 References 163 10 Potentiometric Sensors 165 10.1 Introduction 165 10.2 The Galvanic Cell at Equilibrium 165 10.2.1 Thermodynamics of Electrolyte Solutions 166 10.2.2 Thermodynamics of the Galvanic Cell 167 x Contents 10.3 Ion Distribution at the Interface of Two Electrolyte Solutions 170 10.3.1 Charge Distribution at the Junction of Two Electrolyte Solutions. The Diffusion Potential 170 10.3.2 Ion Distribution at an Aqueous/Semipermeable Membrane Interface 172 10.4 Potentiometric Ion Sensors - General 173 10.4.1 Sensor Configuration and the Response Function 173 10.4.2 Selectivity of Potentiometric Ion Sensors 175 10.4.3 The Response Range of Potentiometric Ion Sensors 177 10.4.4 Interferences by Chemical Reactions Occurring in the Sample 177 10.4.5 The Response Time of Potentiometric Ion Sensors 177 10.4.6 Outlook 178 10.5 Sparingly Soluble Solid Salts as Membrane Materials 178 10.5.1 Membrane Composition 178 10.5.2 Response Function and Selectivity 179 10.6 Glass Membrane Ion Sensors 181 10.6.1 Membrane Structure and Properties 181 10.6.2 Response Function and Selectivity 182 10.6.3 Chalcogenide Glass Membranes 183 10.7 Ion Sensors Based on Molecular Receptors. General Aspects 184 10.8 Liquid Ion Exchangers as Ion Receptors 185 10.8.1 Ion Recognition by Liquid Ion Exchangers 185 10.8.2 Charged Receptor Membranes 185 10.8.3 Response Function and Selectivity 186 10.8.4 Outlook 187 10.9 Neutral Ion Receptors (Ionophores) 187 10.9.1 General Principles 187 10.9.2 Chemistry of Ion Recognition by Neutral Receptors 188 10.9.3 Effect of Bonding Multiplicity, Steric, and Conformational Factors 189 10.9.4 Neutral Receptor Ion-Selective Membranes: Composition, Selectivity and Response Function 190 10.9.5 Neutral Noncyclic Ion Receptors 192 10.9.6 Macrocyclic Cation Receptors 193 10.9.7 Macrocyclic Anion Receptors 194 10.9.8 Neutral Receptors for Organic Ions 194 10.9.9 Porphyrins and Phthalocyanines as Anion Receptors 195 10.9.10 Outlook 196 10.10 Molecularly Imprinted Polymers as Ion-Sensing Materials 197 10.11 Conducting Polymers as Ion-Sensing Materials 198 10.12 Solid Contact Potentiometric Ion Sensors 198 10.13 Miniaturization of Potentiometric Ion Sensors 199 10.14 Analysis with Potentiometric Ion Sensors 200 10.15 Recent Advances in Potentiometric Ion Sensors 201 10.16 Potentiometric Gas Sensors 203 10.17 Solid Electrolyte Potentiometric Gas Sensors 204 10.17.1 General Principles 204 10.17.2 Solid Electrolyte Potentiometric Oxygen Sensors 205 10.17.3 Applications of Potentiometric Oxygen Sensors 206 10.17.4 Types of Solid Electrolyte Potentiometric Gas Sensors 207 10.17.5 Mixed Potential Potentiometric Gas Sensors 208 10.17.6 Outlook 209 10.18 Potentiometric Biocatalytic Sensors 210 10.19 Potentiometric Affinity Sensors 211 10.20 Summary 212 References 213 11 Chemical Sensors Based on Semiconductor Electronic Devices 217 11.1 Electronic Semiconductor Devices 217 11.1.1 Semiconductor Materials 217 11.1.2 Band Theory of Semiconductors 218 11.1.3 Metal-Insulator-Semiconductor (MIS) Capacitors 219 11.1.4 Metal-Insulator-Semiconductor Field Effect Transistors (MISFETs) 221 11.1.5 Outlook 224 11.2 FED Ion Sensors and Their Applications 224 11.2.1 Electrolyte-Insulator-Semiconductor (EIS) Devices 224 11.2.2 FEDpH Sensors 226 11.2.3 pH ISFET-Based Gas Probes 228 11.2.4 Membrane-Covered ISFETs 229 11.2.5 Light-Addressable Potentiometric Sensors (LAPS) 230 11.2.6 Reference Electrodes for ISFET Sensors 231 11.2.7 Enzymatic FET Sensors (EnFETs) 232 11.2.8 Outlook 232 11.3 FED Gas Sensors 234 11.3.1 FED Hydrogen Sensors 234 11.3.2 Metal Gate FED Sensors for Other Gases 235 11.3.3 Organic Semiconductors as Gas-Sensing Materials 236 11.3.4 Organic Semiconductors FED Gas Sensors 237 11.3.5 Response Mechanism of FED Gas Sensors 238 11.3.6 Outlook 240 11.4 Schottky-Diode-Based Gas Sensors 240 11.5 Carbon-Nanotube-Based Field-Effect Transistors 242 11.6 Concluding Remarks 243 References 244 12 Resistive Gas Sensors (Chemiresistors) 246 12.1 Semiconductor Metal Oxide Gas Sensors 246 12.1.1 Introduction 246 12.1.2 Gas-Response Mechanism 246 12.1.3 Response to Humidity 247 12.1.4 Sensor Configuration 248 12.1.5 Synthesis and Deposition of Metal Oxides 249 12.1.6 Fabrication of Metal-Oxide Chemiresistors 249 12.1.7 Selectivity and Sensitivity 250 12.1.8 Outlook 251 12.2 Organic-Material-Based Chemiresistors 252 12.3 Nanomaterial Applications in Resistive Gas Sensors 253 12.4 Resistive Gas Sensor Arrays 254 12.5 Summary 255 References 256 13 Dynamic Electrochemistry Transduction Methods 258 13.1 Introduction 258 13.2 Electrochemical Cells in Amperometric Analysis 258 13.3 The Electrolytic Current and its Analytical Significance 260 13.3.1 Current-Concentration Relationships 260 13.3.2 The Current-Potential Curve: Selecting the Working Potential 262 13.3.3 Irreversible Electrochemical Reactions 264 13.3.4 Sign Convention 265 13.3.5 Geometry of the Diffusion Process 265 13.3.6 Outlook 265 13.4 Membrane-Covered Electrodes 266 13.5 Non-Faradaic Processes 267 13.5.1 Origin of Non-Faradaic Currents 267 13.5.2 The Electrical Double Layer at the Electrode/Solution Interface 268 13.5.3 The Charging Current 269 13.5.4 Applications of Capacitance Measurement in Chemical Sensors 270 13.6 Kinetics of Electrochemical Reactions 270 13.6.1 The Reaction Rate of an Electrochemical Reaction 270 13.6.2 Current-Potential Relationships 272 13.6.3 Mass-Transfer Effect on the Kinetics of Electrochemical Reactions 273 13.6.4 Equilibrium Conditions 274 13.6.5 The Electrochemical Reaction in the Absence of Mass-Transfer Restrictions 275 13.6.6 Polarizable and Nonpolarizable Electrodes 276 13.7 Achieving Steady-State Conditions in Electrochemical Measurements 277 13.7.1 Outlook 278 13.8 Electrochemical Methods 280 13.8.1 Steady-State Method 280 13.8.2 Constant-Potential Chronoamperometry 280 13.8.3 Polarography 281 13.8.4 Linear-Scan Voltammetry(LSV) and Cyclic Voltammetry (CV) 282 13.8.5 Pulse Voltammetry 285 13.8.6 Square-Wave Voltammetry (SWV) 286 13.8.7 Alternating-Current Voltammetry 287 13.8.8 Chronopotentiometric Methods 288 13.8.9 Electrochemistry at Ultramicroelectrodes 289 13.8.10 Current Amplification by Reactant Recycling 291 13.8.11 Scanning Electrochemical Microscopy 292 13.8.12 Outlook 293 13.9 Electrode Materials 294 13.9.1 Carbon Electrodes 295 13.9.2 Noble-Metal Electrodes 296 13.9.3 Metal-Oxide Films 297 13.9.4 Electrode Fabrication 297 13.9.5 Carbon Nanomaterial Applications in Electrochemistry 298 13.9.6 Outlook 298 13.10 Catalysis in Electrochemical Reactions 299 13.10.1 Homogeneous Redox Catalysis 299 13.10.2 Homogeneous Mediation in Electrochemical Enzymatic Reactions 300 13.10.3 Catalysis by Immobilized Enzymes 301 13.10.4 Heterogeneous Redox Catalysis 302 13.10.5 Surface Activation of Electrochemical Reactions 304 13.10.6 Outlook 304 13.11 Amperometric Gas Sensors 306 13.11.1 The Clark Oxygen Sensor 306 13.11.2 Nitric Oxide Sensors 307 13.11.3 Other Types of Amperometric Gas Sensors 308 13.11.4 Galvanic Cell-Type Gas Sensors 309 13.11.5 Solid Electrolyte Amperometric Gas Sensors 309 References 310 14 Amperometric Enzyme Sensors 314 14.1 First-Generation Amperometric Enzyme Sensors 314 14.2 Second-Generation Amperometric Enzyme Sensors 316 14.2.1 Principles 316 14.2.2 Inorganic Mediators 317 14.2.3 Organic Mediators 317 14.2.4 Ferrocene Derivatives as Mediators 319 14.2.5 Electron-Transfer Mediation by Redox Polymers 320 14.2.6 Sensing by Organized Molecular Multilayer Structures 321 14.3 The Mediator as Analyte 322 14.4 Conducting Polymers in Amperometric Enzyme Sensors 323 14.5 Direct Electron Transfer: 3rd-Generation Amperometric Enzyme Sensors 324 14.5.1 Conducting Organic Salt Electrodes 324 14.5.2 Direct Electron Transfer with FAD-Heme Enzymes 325 14.5.3 Achieving Direct Electron Transfer by Means of Nanomaterials 326 14.6 NAD/NADH+ as Mediator in Biosensors 327 14.7 Summary 328 References 328 15 Mathematical Modeling of Mediated Amperometric Enzyme Sensors 332 15.1 External Diffusion Conditions 332 15.1.1 Model Formulation 332 15.1.2 Sensor Response: Limiting Cases 334 15.1.3 The Dynamic Range and the Limit of Detection 336 15.1.4 Other Theoretical Models 338 15.1.5 Outlook 338 15.2 Internal Diffusion Conditions 339 15.2.1 Model Formulation 339 15.2.2 Dimensionless Parameters and Variables 340 15.2.3 Limiting Conditions 342 15.2.4 Solving the Differential Equations. The Case Diagram 343 15.2.5 Kinetic Currents 343 15.2.6 Diffusion Currents 343 15.2.7 Outlook 345 References 345 16 Electrochemical Affinity and Nucleic Acid Sensors 347 16.1 Amperometric Affinity Sensors 347 16.1.1 Redox Labels in Amperometric Immunosensors 347 16.1.2 Enzyme-Linked Amperometric Immunosensors 347 16.1.3 Separationless Amperometric Immunosensors 349 16.1.4 Nanomaterials Applications in Amperometric Immunosensors 350 16.1.5 Imprinted Polymers in Amperometric Affinity Sensors 351 16.1.6 Outlook 353 16.2 Electrochemical Nucleic Acid-Based Sensors 354 16.2.1 Electrochemical Reactions of Nucleobases 354 16.2.2 Amperometric Nucleic Acid Sensors Based on Self-Indicating Hybridization 355 16.2.3 Intercalating Redox Indicators 357 16.2.4 Covalently Bound Redox Indicators in Sandwich Assays 357 16.2.5 Covalently Bound Redox Indicators in Spatially Resolved Transduction 359 16.2.6 Enzyme Labels in Amperometric Nucleic Acid Sensors 359 16.2.7 Electrochemical DNA Arrays 361 16.2.8 Nucleic Acids as Recognition Materials for Non-Nucleotide Compounds 361 16.2.9 Aptamer Amperometric Sensors 361 16.2.10 Outlook 363 References 364 17 Electrical-Impedance-Based Sensors 367 17.1 Electrical Impedance: Terms and Definitions 367 17.2 Electrochemical Impedance Spectrometry 369 17.2.1 Basic Concepts and Definitions 369 17.2.2 Non-Faradaic Processes 370 17.2.3 Faradaic Processes 372 17.2.4 Probing the Electrode Surface by Electrochemical Impedance Spectrometry 373 17.3 Electrochemical Impedance Affinity Sensors 375 17.3.1 Electrochemical Impedance Transduction in Affinity Sensors 375 17.3.2 Configuration of Impedimetric Biosensors 376 17.3.3 Capacitive Biosensors 377 17.3.4 Signal Amplification 379 17.3.5 Synthetic Receptor-Based Impedimetric Sensors 379 17.3.6 Applications of Impedimetric Affinity Sensors 380 17.4 Biocatalytic Impedimetric Sensors 381 17.5 Outlook 382 17.6 Nucleic Acid Impedimetric Sensors 383 17.6.1 Non-Faradaic Impedimetric DNA Sensors 383 17.6.2 Faradaic Impedimetric DNA Sensors 384 17.6.3 Impedimetric Aptasensors 385 17.7 Conductometric Sensors 386 17.7.1 Conductivity of Electrolyte Solutions 386 17.7.2 Conductance Measurement 388 17.7.3 Conductometric Transducers 389 17.7.4 Conductometric Enzymatic Sensors 389 17.7.5 Conductometric Transduction by Chemoresistive Materials 391 17.7.6 Ion-Channel-Based Conductometric Sensors 394 17.7.7 Outlook 394 17.8 Impedimetric Sensors for Gases and Vapors 395 17.8.1 Humidity: Terms and Definitions 395 17.8.2 Resistive Humidity Sensors 396 17.8.3 Capacitive Humidity Sensors 397 17.8.4 Capacitive Gas Sensors 399 17.8.5 Integrated Impedimetric Gas Sensors and Sensor Arrays 399 17.8.6 Outlook 400 References 400 18 Optical Sensors - Fundamentals 404 18.1 Electromagnetic Radiation 404 18.2 Optical Waveguides in Chemical Sensors 405 18.2.1 Optical Fibers: Structure and Light Propagation 406 18.2.2 Passive Fiber Optic Sensor Platforms 407 18.2.3 Active Fiber Optic Sensor Platforms 407 18.2.4 Planar Waveguides 408 18.2.5 Capillary Waveguides 409 18.2.6 Outlook 409 18.3 Spectrochemical Transduction Methods 409 18.3.1 Light Absorption 409 18.3.2 Diffuse Reflectance Spectrometry 410 18.3.3 Luminescence 411 18.3.4 Fluorescence Spectrometry 412 18.3.5 Steady-State Fluorescence Measurements 413 18.3.6 Time-Resolved Fluorimetry 414 18.3.7 Fluorescence Quenching 416 18.3.8 Resonance Energy Transfer 417 18.3.9 Chemiluminescence and Bioluminescence 417 18.3.10 Electrochemically Generated Chemiluminescence 418 18.3.11 Raman Spectrometry 419 18.3.12 Outlook 420 18.4 Transduction Schemes in Spectrochemical Sensors 421 18.4.1 Direct Transduction 421 18.4.2 Indirect (Competitive-Binding) Transduction 423 18.4.3 Outlook 424 18.5 Fiber Optic Sensor Arrays 424 18.6 Label-Free Transduction in Optical Sensors 425 18.6.1 Surface Plasmons Resonance Spectrometry 425 18.6.2 Interferometric Transduction 426 18.6.3 The Resonant Mirror 428 18.6.4 Resonant Waveguide Grating 429 18.6.5 Outlook 429 18.7 Transduction by Photonic Devices 430 18.7.1 Optical Microresonators 430 18.7.2 Photonic Crystals 431 18.7.3 Outlook 433 References 433 19 Optical Sensors - Applications 435 19.1 Optical Sensors Based on Acid-Base Indicators 435 19.1.1 Optical pH Sensors 435 19.1.2 Optical Sensors for Acidic and Basic Gases 437 19.2 Optical Ion Sensors 438 19.2.1 Direct Optical Ion Sensors 438 19.2.2 Indirect Optical Ion Sensors 439 19.3 Optical Oxygen Sensors 440 19.4 Enzymatic Optical Sensors 442 19.4.1 Principles and Design 442 19.4.2 Optical Monitoring of Reactants or Products 442 19.4.3 Coenzyme-Based Optical Transduction 443 19.4.4 Outlook 443 19.5 Optical Affinity Sensors 444 19.5.1 Optical Immunosensors 444 19.5.2 Optical Sensors Based on Biological Receptors 445 19.5.3 Outlook 446 19.6 Optical DNA Sensors and Arrays 447 19.6.1 Fluorescence Transduction in Nucleic Acid Sensors 447 19.6.2 Fiber Optic Nucleic Acid Sensors 448 19.6.3 Fiber Optic Nucleic Acid Arrays 450 19.6.4 Optical DNA Microarrays 451 19.6.5 Outlook 451 References 452 20 Nanomaterial Applications in Optical Transduction 454 20.1 Semiconductor Nanocrystals (Quantum Dots) 454 20.1.1 Quantum Dots: Structure and Properties 454 20.1.2 Applications of Quantum Dots in Chemical Sensing 456 20.1.3 Outlook 461 20.2 Carbon Nanotubes as Optical Labels 462 20.2.1 Light Absorption and Emission by CNTs 462 20.2.2 Raman Scattering by CNTs 464 20.2.3 CNT Optical Sensors and Arrays 464 20.2.4 Outlook 466 20.3 Metal Nanoparticle in Optical Sensing 466 20.3.1 Optical Properties of Metal Nanoparticles 466 20.3.2 Optical Detection Based on Metal Nanoparticles 467 20.3.3 Metal Nanoparticles in Optical Sensing 468 20.4 Porous Silicon 470 20.5 Luminescent Lanthanide Compound Nanomaterials 471 20.6 Summary 471 References 471 21 Acoustic-Wave Sensors 473 21.1 The Piezoelectric Effect 473 21.2 The Thickness-Shear Mode Piezoelectric Resonator 474 21.2.1 The Quartz Crystal Microbalance 474 21.2.2 The Unperturbed Resonator 476 21.2.3 QCM Loading by a Rigid Overlayer. The Sauerbrey Equation 477 21.2.4 The QCM in Contact with Liquids 478 21.2.5 The QCM in Contact with a newtonian Liquid 479 21.2.6 The QCM in Contact with a Viscoelastic Fluid 480 21.2.7 Modeling the Loaded TSM Resonator 480 21.2.8 The Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) 485 21.2.9 Operation of QCM Sensors 486 21.2.10 Calibration of the QCM 487 21.2.11 Outlook 488 21.3 QCM Gas and Vapor Sensors 489 21.4 QCM Affinity Sensors 489 21.4.1 QCM Immunosensor 490 21.4.2 Amplification in QCM Immunosensors 491 21.4.3 Determination of Small Molecules Using Natural Receptors 492 21.4.4 QCM Sensors Based on Molecularly Imprinted Polymers 492 21.4.5 QCM Sensors Based on Small Synthetic Receptors 494 21.4.6 Outlook 494 21.5 QCM Nucleic Acid Sensors 495 21.5.1 Hybridization Sensors 495 21.5.2 Piezoelectric Aptasensors 496 21.5.3 Outlook 497 21.6 Surface-Launched Acoustic-Wave Sensors 497 21.6.1 Principles 497 21.6.2 The Surface Acoustic Wave 498 21.6.3 Plate-Mode SLAW Devices 498 21.6.4 SLAW Gas and Vapor Sensors 499 21.6.5 Liquid-Phase SLAW Sensing 501 21.6.6 Outlook 502 21.7 Summary 503 References 504 22 Microcantilever Sensors 507 22.1 Principles of Microcantilever Transduction 507 22.1.1 The Microcantilever 507 22.1.2 Static Deformation Transduction 508 22.1.3 Resonance-Mode Transduction 509 22.2 Measurement of Cantilever Deflection 510 22.2.1 Optical Measurement of Cantilever Deflection 510 22.2.2 Electrical Measurement of Cantilever Deflection 511 22.3 Functionalization of Microcantilevers 512 22.4 Microcantilever Gas and Vapor Sensors 513 22.5 Microcantilever Affinity Sensors 513 22.5.1 General Aspects 513 22.5.2 Microcantilever Protein Sensors 513 22.5.3 Microcantilever Pathogen Sensors 514 22.5.4 Microcantilever Affinity Sensors Based on Other Recognition Receptors 514 22.6 Enzyme Assay by Microcantilever Sensors 515 22.7 Microcantilever Nucleic Acid Sensors 515 22.8 Outlook 516 References 516 23 Chemical Sensors Based on Micro-Organisms, Living Cells and Tissues 518 23.1 Living Material Biosensors: General Principles 518 23.2 Sensing Strategies in Living-Material-Based Sensors 518 23.2.1 Biocatalytic Sensors 518 23.2.2 External-Stimuli-Based Biosensors 519 23.3 Immobilization of Living Cells and Micro-organisms 519 23.4 Electrochemical Microbial Biosensors 520 23.4.1 Amperometric Microbial Biosensors 520 23.4.2 Potentiometric Microbial Biosensors 522 23.4.3 Conductometric Microbial Sensors 523 23.4.4 Electrical Impedance Transduction 523 23.5 Optical Whole-Cell Sensors 524 23.5.1 Optical Respiratory Biosensors 524 23.5.2 External-Stimuli-Based Optical Sensors 525 23.5.3 Bioreporters 526 23.6 Improving the Selectivity of Micro-organism Biosensors 526 23.7 Conclusions 527 References 528 Index 531

About the Author

Dr Florinel-Gabriel BANICA is Associate Professor at the Norwegian University of Science and Technology, Dept of Chemistry. Prior to this he was at the Technical University of Bucharest, Romania. Florin’s research is focused on bioelectrochemistry, and functionalized materials for chemical sensor applications. He teaches undergraduate courses on analytical chemistry, instrumental analysis, electroanalytical chemistry and physical chemistry, and graduate courses on atomic spectrometry and chemical sensors and biosensors (on which this book is based).

Reviews

"Summary In conclusion it can be stated that this book is very suitable for students and a sound didactic means of learning the basics of chemo and biosensors ... The organization of the content and the quantity of material presented are highly suitable for undergraduate and graduate students and for newcomers to this field; it can, therefore, be recommended for those wishing to gain both a first insight into, and a comprehensive overview of, this still growing topic." (Analytical and Bioanalytical Chemistry, 1 March 2013)